Laird Connectivity 4424200 FREQUENCY HOPPING SPREAD SPECTRUM TRANSCEIVER User Manual AC4424
AeroComm Corporation FREQUENCY HOPPING SPREAD SPECTRUM TRANSCEIVER AC4424
Contents
- 1. Users Manual 1
- 2. Users Manual 2
Users Manual 2
3/23/2006 2
DOCUMENT INFORMATION
Limited Warranty, Disclaimer, Limitation of Liability
For a period of one (1) year from the date of purchase by the OEM customer, Laird Technologies
warrants the OEM transceiver against defects in materials and workmanship. Laird Technologies
will not honor this warranty (and this warranty will be automatically void) if there has been any (1)
tampering, signs of tampering; 2) repair or attempt to repair by anyone other than an Laird
Technologies authorized technician.
This warranty does not cover and Laird Technologies will not be liable for, any damage or failure
caused by misuse, abuse, acts of God, accidents, electrical irregularity, or other causes beyond
Laird Technologies’s control, or claim by other than the original purchaser.
In no event shall Laird Technologies be responsible or liable for any damages arising: From the
use of product; From the loss of use, revenue or profit of the product; or As a result of any event,
circumstance, action, or abuse beyond the control of Laird Technologies, whether such
damages be direct, indirect, consequential, special or otherwise and whether such damages are
incurred by the person to whom this warranty extends or third party.
If, after inspection, Laird Technologies determines that there is a defect, Laird Technologies will
repair or replace the OEM transceiver at their discretion. If the product is replaced, it may be a
new or refurbished product.
Copyright
Information
Copyright © 2009 Laird Technologies, Inc. All rights reserved.
The information contained in this manual and the accompanying
software programs are copyrighted and all rights are reserved by
Laird Technologies, Inc. Laird Technologies, Inc. reserves the right to make
periodic modifications of this product without obligation to notify
any person or entity of such revision. Copying, duplicating, selling, or otherwise
distributing any part of this product without the prior consent of an authorized
representative of Laird Technologies, Inc. is prohibited.
All brands and product names in this publication are registered
trademarks or trademarks of their respective holders.
This material is preliminary
Information furnished by Laird Technologies in this specification is believed to be accurate.
Devices sold by Laird Technologies are covered by the warranty and patent indemnification
provisions appearing in its Terms of Sale only. Laird Technologies makes no warranty, express,
statutory, and implied or by description, regarding the information set forth herein. Laird
Technologies reserves the right to change specifications at any time and without notice.
Laird Technologies products are intended for use in normal commercial and industrial
applications. Applications requiring unusual environmental requirements such as military,
medical life-support or life-sustaining equipment are specifically not recommended without
additional testing for such application.
3/23/2006 3
DOCUMENT INFORMATION
Revision Description
Version 1.0.0 5/5/2009 – Initial Release Version
3/23/2006 4
TABLE OF CONTENTS
1. OVERVIEW ......................................................................................................................................6
2. LT4424 SPECIFICATIONS.............................................................................................................7
3. SPECIFICATIONS...........................................................................................................................8
3.1 INTERFACE SIGNAL DEFINITIONS .........................................................................................................8
3.2 ELECTRICAL SPECIFICATIONS...............................................................................................................9
3.3 SYSTEM TIMING ...................................................................................................................................9
3.3.1 Serial Interface Data Rate...........................................................................................................9
3.3.2 Timing Diagrams.......................................................................................................................10
3.3.3 Maximum Overall System Throughput ......................................................................................11
4. CONFIGURING THE LT4424 ......................................................................................................12
4.1 EEPROM PARAMETERS ....................................................................................................................12
4.2 CONFIGURING THE LT4424 ...............................................................................................................14
4.3 COMMAND REFERENCE ......................................................................................................................15
4.4 LT4424 AT COMMANDS....................................................................................................................16
4.4.1 Enter AT Command Mode.........................................................................................................16
4.4.2 Exit AT Command Mode............................................................................................................16
4.5 ON-THE-FLY CONTROL COMMANDS (CC COMMAND MODE) ............................................................17
4.5.1 Status Request............................................................................................................................17
4.5.2 Change Channel with Forced Acquisition Sync ........................................................................18
4.5.3 Server/Client..............................................................................................................................18
4.5.4 Broadcast Mode.........................................................................................................................18
4.5.5 Write Destination Address.........................................................................................................20
4.5.6 Read Destination Address..........................................................................................................20
4.5.7 EEPROM Byte Read..................................................................................................................20
4.5.8 EEPROM Byte Write .................................................................................................................20
4.5.9 Reset ..........................................................................................................................................21
5. THEORY OF OPERATION ..........................................................................................................22
5.1 HARDWARE INTERFACE......................................................................................................................22
5.1.1 TXD (Transmit Data) and RXD (Receive Data) (pins 2 and 3 respectively).............................22
5.1.2 Hop Frame (pin 6).....................................................................................................................22
5.1.3 CTS Handshaking (pin 7) ..........................................................................................................22
5.1.4 RTS Handshaking (pin 8)...........................................................................................................22
5.1.5 9600 Baud/Packet Frame (pin 12).............................................................................................23
5.1.6 RSSI (pin 13)..............................................................................................................................23
5.1.7 Wr_ENA(EEPROM Write Enable) (pin 14) ..............................................................................23
5.1.8 UP_RESET (pin 15)...................................................................................................................23
5.1.9 Command/Data (pin 17)............................................................................................................23
5.1.10 In Range (pin 20).......................................................................................................................24
5.2 SOFTWARE PARAMETERS ...................................................................................................................25
5.2.1 RF Architecture (Server-Client/Peer-to-Peer) ..........................................................................25
5.2.2 RF Mode....................................................................................................................................25
5.2.3 Random Back Off.......................................................................................................................26
5.2.4 Duplex Mode .............................................................................................................................26
5.2.5 Interface Timeout/RF Packet Size..............................................................................................27
5.2.6 Serial Interface Baud Rate.........................................................................................................27
5.2.7 Auto Config................................................................................................................................28
6. DIMENSIONS .................................................................................................................................29
3/23/2006 5
7. ORDERING INFORMATION.......................................................................................................30
7.1 PRODUCT PART NUMBERS..................................................................................................................30
7.2 DEVELOPER KIT PART NUMBERS .......................................................................................................30
8. REGULATORY INFORMATION................................................................................................31
8.1 AGENCY IDENTIFICATION NUMBERS ..................................................................................................31
8.2 APPROVED ANTENNA LIST.................................................................................................................31
8.3 FCC/IC REQUIREMENTS FOR MODULAR APPROVAL .........................................................................31
8.4 OEM EQUIPMENT LABELING REQUIREMENTS ...................................................................................32
8.5 ANTENNA REQUIREMENTS .................................................................................................................32
8.6 WARNINGS REQUIRED IN OEM MANUALS ........................................................................................32
Figures
Figure 1 – RSSI Voltage vs. Received Signal Strength.................................Error! Bookmark not defined.
Figure 2 – LT4424 with MMCX.................................................................................................................. 29
Tables
Table 1 – Pin Definitions................................................................................................................................ 8
Table 2 – DC Input Voltage Characteristics................................................................................................... 9
Table 3 – DC Output Voltage Characteristics ................................................................................................ 9
Table 4 – Timing Parameters........................................................................................................................ 11
Table 5 – Maximum Overall System Throughputs ...................................................................................... 11
Table 6 – EEPROM Parameters................................................................................................................... 12
Table 7 – Baud Rate ..................................................................................................................................... 27
Table 8 – Auto Config Parameters ............................................................................................................... 28
3/23/2006 6
LT4424 Features
Simple 5V TTL level serial interface for fast integration
Frequency Hopping Spread Spectrum for security and interference rejection
Cost Efficient for high volume applications
Low power consumption for battery powered implementations
Small size for portable and enclosed applications
Very Low latency and high throughput
Industrial temperature (-40°C to 80°C)
1. Overview
The LT4424 is a member of Laird Technologies’s ConnexRF OEM transceiver family. It is designed for
integration into OEM systems operating under FCC part 15.247 regulations for the 2.4 GHz ISM band.
The LT4424 is a cost-effective, High performance, 2.4 GHz frequency hopping spread spectrum
transceiver. It provides an asynchronous TTL level serial interface for OEM Host communications.
Communications include both system and configuration data. The Host supplies system data for
transmission to other Host(s). Configuration data is stored in an on-board EEPROM. All frequency
hopping, synchronization, and RF system data transmission/reception is performed by the transceiver.
The LT4424 transceivers can be used as a direct serial cable replacement – requiring no special Host
software for operation. They also feature a number of On-the-Fly Control Commands providing the
OEM Host with a very versatile interface for any situation.
LT4424 transceivers operate in a Point-to-Point or Point-to-Multipoint, Client-Server or Peer-to-Peer
architecture. One transceiver is configured as a Server and there can be one or many Clients. To
establish synchronization between transceivers, the Server emits a beacon. Upon detecting a beacon,
a Client transceiver informs its Host and a RF link is established.
There are two data rates the OEM should be aware of:
• Serial Interface Data Rate – All transceivers can be configured to common PC serial port
baud rates from 110 bps to 288000 bps.
• Effective Data Transmission Rate – The LT4424 is a highly efficient, low-latency
transceiver. The RF baud rate of the LT4424 is fixed at 576 kbps and is independent of
the serial interface data rate.
This document contains information about the hardware and software interface between a Laird
Technologies LT4424 transceiver and an OEM Host. Information includes the theory of operation,
specifications, interface definition, configuration information and mechanical drawing.
The OEM is responsible for ensuring the final product meets all FCC and/or appropriate regulatory
agency requirements listed herein before selling any product.
3/23/2006 7
2. LT4424 Specifications
GENERAL
Interface 20 pin mini-connector
Serial Interface Data Rate PC baud rates from 110 bps to 288,000 bps
Power Consumption (typical) Duty Cycle (TX=Transmit; RX=Receive)
10%TX 50%TX 100%TX 100%RX Pwr-Down
LT4424-200: 115 mA 235 mA 385 mA 85 mA 15 mA
Channels (used to create independent networks) US/Canada: (200 mW) 16 Channels
Security One byte System ID
Interface Buffer Size Input/Output: 256 bytes each
RADIO
Frequency Band US/Canada (200mW): 2.402 – 2.478 GHz
Radio Type Frequency-Hopping Spread Spectrum
Output Power (conducted, no antenna) LT4424-200: 400mW typical
Effective Isotropic Radiated Power (EIRP with
5dBi gain antenna)
LT4424-200: 1000mW typical
Voltage 5V nominal ±2%, ±50mV ripple
Sensitivity -90dBm typical
Range (based on dBi gain antenna) LT4424-200: Indoors to 500 ft., Outdoors to 15000 ft.
ENVIRONMENTAL
Temperature (Operating) Industrial: -40°C to 80°C
Temperature (Storage) -50°C to 85°C
Humidity (non-condensing) 10% to 90%
PHYSICAL
Dimensions 1.65” x 2.65” x 0.20”
Antenna LT4424-200: MMCX Jack
Weight Less than 0.7 ounce
3/23/2006 8
3. Specifications
3.1 INTERFACE SIGNAL DEFINITIONS
The LT4424 has a simple interface that allows OEM Host communications with the transceiver. Table 1
– Pin Definitions, shows the connector pin numbers and associated functions. The I/O direction is with
regard to the transceiver. All I/O is 5VDC TTL level signals except for RSSI. All inputs are weakly pulled
High and may be left floating during normal operation.
Table 1 – Pin Definitions
Pin Type Signal Name Function
1 NC No Connect
2 O TXD Transmitted data out of the transceiver
3 I RXD Data input to the transceiver
4 NC No Connect
5 GND GND Signal Ground
6 O Hop Frame HOP FRAME – Active Low when the transceiver is hopping.
7 O CTS Clear to Send – Active Low when the transceiver is ready to accept data for transmission.
8 I RTS Request to Send – When enabled in EEPROM, active Low when the OEM Host is ready to
accept data from the transceiver. NOTE: Keeping RTS High for too long can cause data loss.
9 NC No Connect
10 PWR VCC 5V ± 2%, ± 50mV ripple
11 PWR VCC 5V ± 2%, ±50 mV ripple
12 I/O 9600_BAUD/
Packet Frame
9600_BAUD – When pulled logic Low before applying power or resetting the transceiver’s
serial interface is forced to a 9600, 8, N, 1 rate. To exit, transceiver must be reset or power-
cycled with 9600_Baud logic High.
*Note: 9600_BAUD should only be used to recover the radio from an unknown baud rate and
should not be used during normal operation.
Packet Frame – When programmed in EEPROM, Packet Frame will transition logic Low at the
start of a received RF packet and transition logic High at the completion of the packet.
13 O RSSI Received Signal Strength Indicator - An analog output giving a relative indication of received
signal strength while in Receive Mode.
14 I WR_ENA EEPROM Write Enable – When pulled logic Low, it allows the Host to write the on-board
EEPROM. Resetting the transceiver with this pin pulled Low may corrupt EEPROM data.
15 I UP_RESET RESET – Controlled by the LT4424 for power-on reset if left unconnected. After a Stable power-
on (250ms) a 50us logic High pulse will reset the LT4424. Do not power up the transceiver
with this pin tied Low.
16 GND GND Signal Ground
17 I Command/Data When logic Low, transceiver interprets Host data as command data. When logic High,
transceiver interprets Host data as transmit data.
18 NC No Connect
19 NC No Connect
20 O IN_RANGE In Range – Active Low when a Client radio is in range of a Server on same Channel with the same
System ID.
I = Input to the transceiver O = Output from the transceiver
3/23/2006 9
3.2 ELECTRICAL SPECIFICATIONS
Table 2 – DC Input Voltage Characteristics
Pin Type Name High Min. High Max. Low Min. Low Max. Unit
3 I RXD 0.2Vcc+0.9 Vcc+0.5 -0.5 0.2Vcc-0.1 V
8 I RTS 0.2Vcc+0.9 Vcc+0.5 -0.5 0.2Vcc-0.1 V
12 I 9600_Baud 0.2Vcc+0.9 Vcc+0.5 -0.5 0.2Vcc-0.1 V
14 I WR_ENA 0.7Vcc Vcc+1 -0.3 0.5 V
15 I UP_RESET 0.7Vcc Vcc+0.5 -0.5 0.2Vcc-0.1 V
17 I Command/Data 0.2Vcc+0.9 Vcc+0.5 -0.5 0.2Vcc-0.1 V
Table 3 – DC Output Voltage Characteristics
Pin Type Name High Min. Low Max. Unit
2 O TXD Vcc-0.7 @ -30μA 0.4 @ 1.6mA V
6 O Hop Frame Vcc-0.7 @ -30μA 0.4 @ 1.6mA V
7 O CTS Vcc-0.7 @ -30μA 0.4 @ 1.6mA V
12 O Packet Frame Vcc-0.7 @ -30μA 0.4 @ 1.6mA V
13 O RSSI See Figure 1 See Figure 1 V
20 O IN_RANGE Vcc-0.7 @ -30μA 0.4 @ 1.6mA V
3.3 SYSTEM TIMING
Care should be taken when selecting transceiver architecture as it can have serious effects on data
rates, latency timings, and Overall System Throughput. The importance of these three characteristics
will vary from system to system and should be a strong consideration when designing the system.
3.3.1 Serial Interface Data Rate
The Serial Interface Data Rate is programmable by the Host. This is the rate the Host and transceiver
communicate over the serial bus. Possible values range from 110 bps to 288,000 bps. The only
supported mode is asynchronous – 8-bit, No Parity, 1 Start Bit, and 1 Stop Bit.
3/23/2006 10
3.3.2 Timing Diagrams
Addressed Acknowledge Mode with Interface Timeout:
Addressed Acknowledge Mode with No Interface Timeout:
Broadcast Acknowledge Mode with No Interface Timeout:
Local_RXD
Local_RF_TXD
Remote_RF_TXD
Remote_TXD
Hop_Frame
Packet Data
RF Packet
Received Data
Hop Time
Wait for Hop
Hop Period
Local_RXD
Local_RF_TXD
Remote_RF_TXD
Remote_TXD
Hop_Frame
Packet Data
RF Packet
Received Data
RF Acknow ledge
Hop Time
Wait for Hop
Hop Period
Local_RXD
Local_RF_TXD
Remote_RF_TXD
Remote_TXD
Hop_Frame
Packet Data
RF Packet
Received Data
RF Acknow ledge
Hop Time
Hop Period
Interface Timeout
Wait for Hop
3/23/2006 11
Broadcast Acknowledge Mode with Interface Timeout:
Table 4 – Timing Parameters
3.3.3 Maximum Overall System Throughput
When configured as shown in the table below, an LT4424 transceiver is capable of achieving the listed
throughput. However, in the presence of interference or at longer ranges, the transceiver may not be
able to meet these specified throughputs.
Table 5 – Maximum Overall System Throughputs
RF Mode Interface Baud
Rate
Duplex Direction Throughput
(bps)
Acknowledge
115200 Half One way 80k
Acknowledge
115200 Full Both ways 40k
Parameter Typical Time (ms)
Hop Time 1
Hop Period 8
Local_RXD
Local_RF_TXD
Remote_RF_TXD
Remote_TXD
Hop_Frame
Packet Data
RF Packet
Received Data
Hop Time
Hop Period
Interface Timeout
Wait for Hop
3/23/2006 12
4. Configuring the LT4424
4.1 EEPROM PARAMETERS
A Host can program various parameters that are stored in EEPROM and become active after a power-
on reset. Table 6 – EEPROM Parameters, gives the locations and descriptions of the parameters that
can be read or written by a Host. Factory default values are also shown. Do not write to any EEPROM
addresses other than those listed below. Do not copy a transceiver’s EEPROM data to another
transceiver. Doing so may cause the transceiver to malfunction.
Table 6 – EEPROM Parameters
Parameter
EEPROM
Address
Length
(Bytes)
Range Default Description
Product ID 00H 40 40 bytes - Product identifier string.
Includes revision information for software
and hardware.
Channel
Number
40H 1 00 – 0Fh
00h Refer to Table 8
Server/Client
Mode
41H 1 01 – 02h
02h 01h = Server
02h = Client
Baud Rate Low
42H 1 00 – FFh
05h Low Byte of the interface baud rate.
Baud Rate High
43H 1 00 – FFh
00h High Byte of the interface baud rate.
Control 0 45H 1 00010100b
(14h)
Settings are:
Bit 7 – Laird Technologies Use Only
Bit 6 – Laird Technologies Use Only
Bit 5 – Reserved (Set to Zero)
Bit 4 – Laird Technologies Use Only
Bit 3 – Packet Frame
0 = Disable Packet Frame
1 = Use pin 12 as Packet Frame
Bit 2 – Laird Technologies Use Only
Bit 1 – RF Delivery
0 = Addressed
1 = Broadcast
Bit 0 – Laird Technologies Use Only
Transmit
Retries
4CH 1 01 – FFh
10h Maximum number of times a packet is
sent out when Addressed Packets are
selected.
Broadcast
Attempts
4DH 1 01 – FFh
04h Maximum number of times a packet is
sent out when Broadcast Packets are
selected.
3/23/2006 13
Parameter
EEPROM
Address
Length
(Bytes)
Range Default Description
API Control 56H 1 01000011b
= 43h
Settings are:
Bit 7 – Laird Technologies Use Only
Bit 6 – RF Architecture
0 = Server-Client
1 = Peer-to-Peer
Bit 5 – Laird Technologies Use Only
Bit 4 – Auto Destination
0 = Use Destination Address
1 = Automatically set Destination to
Server
Bit 3 – Laird Technologies Use Only
Bit 2 – RTS Enable
0 = RTS Ignored
1 = Transceiver obeys RTS
Bit 1 – Duplex Mode
0 = Half Duplex
1 = Full Duplex
Bit 0 – Auto Config
0 = Use EEPROM values
1 = Auto Configure Values
Interface
Timeout
58H 1 01 – FFh
F0h Specifies a byte gap timeout, used in
conjunction with RF Packet Size to
determine when a packet coming over the
interface is complete (160 μs per
increment).
RF Packet Size
5BH 1 01 – 40h
40h Used in conjunction with Interface
Timeout; specifies the maximum size of
an RF packet.
CTS On 5CH 1 01 – FFh
C0h CTS will be deasserted (High) when the
transmit buffer contains at least this many
characters
CTS On
Hysteresis
5DH 1 01 – FFh
80h Once CTS has been deasserted, CTS will
be reasserted (Low) when the transmit
buffer contains this many or less
characters.
Destination ID
70H 6 6 Bytes Specifies destination for RF packets.
System ID 76H 1 00 – FFh
01h Similar to network password. Radios must
have the same System ID to
communicate with each other.
MAC ID 80H 6 6 Bytes Unique IEEE MAC Address
Random
Backoff
C3h 1 00 - FFh
00h 00h = Disable Random Backoff
01h = Wait 1-2 packet times, then retry
03h = Wait 1-4 packet times, then retry
07h = Wait 1-8 packet times, then retry
0Fh = Wait 1-16 packet times, then retry
1Fh = Wait 1-32 packet times, then retry
3Fh = Wait 1-64 packet times, then retry
7Fh = Wait 1-128 packet times, then retry
FFh = Wait 1-256 packet times, then retry
3/23/2006 14
4.2 CONFIGURING THE LT4424 1
4.3
1 Resetting the LT4424 at any time will exit Configuration or CC Command mode.
No
No
Send CC
Command
Send “Enter AT” Command
(Software Configuration)
Take Pin
17 High
Receive
Mode
Send CC
Commands?
Exit
Command
Mode?
Send another
CC
Command?
Use AT
Commands?
Take Pin 17 Low
(Hardware Configuration)
Receive
Mode
In AT
Command
Mode?
Send
“Exit AT”
Command
No
No
No
3/23/2006 15
COMMAND REFERENCE
Command
Name
Command (All Bytes in Hex) Return (All Bytes in Hex)
AT Enter
Command
Mode
41h 54h
2Bh
2Bh
2Bh 0Dh CCh 43h 4Fh 4Dh
Exit AT
Command
Mode
CCh 41h
54h 4Fh 0Dh CCh 44h 41h 54h
Status
Request CCh 00h
00h — CCh Firmware
Version
00h: Server In Range
01h: Client In Range
02h: Server Out of Range
03h: Client Out of Range
Change
Channel with
Forced
Acquisition
CCh 02h
New
Channel — CCh
New
Channel — —
Server/Client CCh 03h
00h – Server in Normal
Operation
01h – Client in Normal
Operation
02h – Server in Acquisition
Sync
03h – Client in Acquisition Sync
CCh Firmware
Version
00h – Server in Normal Operation
01h – Client in Normal Operation
02h – Server in Acquisition Sync
03h – Client in Acquisition Sync
Power-Down CCh
06h
— — CCh Channel — —
Power-Down
Wake-Up CCh 07h
— — CCh Channel — —
Broadcast
Mode CCh 08h
00h:
Addressed
01h:
Broadcast -
CCh 00h or 01h — —
Write
Destination
Address
CCh 10h
Byte 4 of destination’s MAC
Byte 5 of
destination’s
MAC
Byte 6 of
destination’s
MAC
CCh
Byte 4 of
destination’s
MAC
Byte 5 of
destination’s
MAC
Read
Destination
Address
CCh 11h
— — CCh
Byte 4 of
destination’s
MAC
Byte 5 of
destination’s
MAC
Byte 6 of
destination’s
MAC
Byte 6 of
destination’s
MAC
EEPROM
Byte Read CCh C0h Start
Address
Length
(01h – 80h) CCh Start
Address Length Data at
Addresses
EEPROM
Byte Write CCh C1h Address Length
(01h)
Data to be
Written Address Length
(01h) Data Written
Soft Reset CCh FFh CCh FFh
No
3/23/2006 16
4.4 LT4424 AT COMMANDS
The AT Command mode implemented in the LT4424 creates a virtual version of the Command/Data
pin. The “Enter AT Command Mode” Command asserts this virtual pin Low (to signify Command
Mode) and the “Exit AT Command Mode” Command asserts this virtual pin High (to signify Data).
Once this pin has been asserted Low, all On-the-Fly CC Commands documented in the manual are
supported.
When in AT Command Mode, the user cannot send or receive RF packets. However, an ambiguity of
approximately 10 ms exists where, if the “Enter AT Command Mode” command has been sent to the
transceiver at the same time an RF packet is being received, the RF packet could be sent to the OEM
Host before the “Enter AT Command Mode” command response is sent to the OEM Host.
NOTE: The RF packet size must be set to a minimum of 6 bytes in order to enter Command mode
using the Enter AT Command mode command.
4.4.1 Enter AT Command Mode
Prior to sending the “Enter AT Command Mode” command to the transceiver, the OEM Host must
ensure that the RF transmit buffer of the transceiver is empty (if the buffer is not empty, the ”Enter AT
Command Mode” command will be interpreted as packet data and will be transmitted out over the
RF). This can be accomplished by waiting up to one second between the last transmit packet and the
AT Command. The OEM Host must also ensure that the RF Packet Size for the transceiver is set to a
minimum of six. The Enter AT Command mode command is as follows:
OEM Host Command:
41h 54h 2Bh 2Bh 2Bh 0Dh
Transceiver Response:
CCh 43h 4Fh 4Dh
4.4.2 Exit AT Command Mode
To exit AT Command Mode, the OEM Host should send the following command to the transceiver:
OEM Host Command:
CCh 41h 54h 4Fh 0Dh
Transceiver Response:
CCh 44h 41h 54h
3/23/2006 17
4.5 ON-THE-FLY CONTROL COMMANDS (CC COMMAND MODE)
The LT4424 transceiver contains static memory that holds many of the parameters that control the
transceiver operation. Using the “CC” command set allows many of these parameters to be changed
during system operation. Because the memory these commands affect is static, when the transceiver
is reset, these parameters will revert back to the settings stored in the EEPROM.
While in CC Command mode using pin 17 (Command/Data), the RF interface of the transceiver is still
active. Therefore, it can receive packets from remote transceivers while in CC Command mode and
forward these to the OEM Host. While in CC Command mode using AT Commands, the RF interface
of the transceiver is active, but packets sent from other transceivers will not be received. The
transceiver uses Interface Timeout/RF Packet Size to determine when a CC Command is complete.
Therefore, there should be no delay between each character as it is sent from the OEM Host to the
transceiver or the transceiver will not recognize the command. If the OEM Host has sent a CC
Command to the transceiver and an RF packet is received by the transceiver, the transceiver will send
the CC Command response to the OEM Host before sending the packet. However, if an RF packet is
received before the Interface Timeout expires on a CC Command, the transceiver will send the packet
to the OEM Host before sending the CC Command response.
When an invalid command is sent, the radio scans the command to see if it has a valid command
followed by bytes not associated with the command, in which case the radio discards the invalid bytes
and accepts the command. In all other cases, the radio returns the first byte of the invalid command
back to the user and discards the rest.
The EEPROM parameters and a Command Reference are available in Section 4, Configuring the
LT4424, of this manual.
4.5.1 Status Request
The Host issues this command to request the status of the transceiver.
Host Command:
Byte 1 = CCh
Byte 2 = 00h
Byte 3 = 00h
Transceiver Response:
Byte 1 = CCh
Byte 2 = Firmware version number
Byte 3 = Data1
Where:
Data1 =
00 for Server in Normal Operation
01 for Client in Normal Operation
02 for Server in Acquisition Sync
03 for Client in Acquisition Sync
3/23/2006 18
4.5.2 Change Channel with Forced Acquisition Sync
The Host issues this command to change the channel of the transceiver and force the transceiver to
actively begin synchronization.
Host Command:
Byte 1 = CCh
Byte 2 = 02h
Byte 3 = RF Channel Number (Hexadecimal)
Transceiver Response:
Byte 1 = CCh
Byte 2 = RF Channel Number (Hexadecimal)
4.5.3 Server/Client
The Host issues this command to change the mode (Server or Client) of the transceiver and can force
the transceiver to actively begin synchronization.
Host Command:
Byte 1 = CCh
Byte 2 = 03h
Byte 3 = Data1
Where:
Data1 =
00 for Server in Normal Operation
01 for Client in Normal Operation
02 for Server in Acquisition Sync
03 for Client in Acquisition Sync
Transceiver Response:
Byte 1 = CCh
Byte 2 = Firmware Version Number
Byte 3 = Data1
Where:
Data1 = Data1 from Host Command
4.6 BROADCAST MODE
The Host issues this command to change the transceiver operation between Addressed Mode and
Broadcast Mode. If addressed mode is selected the transceiver will send all packets to the radio
designated by the Destination Address programmed in the transceiver.
Host Command:
Byte 1 = CCh
Byte 2 = 08h
Byte 3 = 00 for addressed mode, 01 for broadcast mode
Transceiver Response:
Byte 1 = CCh
3/23/2006 19
Byte 2 = 00 for addressed mode, 01 for broadcast mode
3/23/2006 20
4.7 WRITE DESTINATION ADDRESS
The Host issues this command to the transceiver to change the Destination Address. This is a very
powerful command that provides the OEM Host with a means for ad-hoc networking. Only the three
Least Significant Bytes of the MAC Address are used for packet delivery.
Host Command:
Byte 1 = CCh
Byte 2 = 10h
Bytes 3 – 5 = 00 – FFh corresponding to the three LSB’s of the destination MAC Address
Transceiver Response:
Byte 1 = CCh
Bytes 2 – 4= 00 – FFh corresponding to the three LSB’s of the destination MAC Address
4.8 READ DESTINATION ADDRESS
The Host issues this command to the transceiver to read the Destination Address. This is a very
powerful command that provides the OEM Host with a means for ad-hoc networking. Only the three
Least Significant Bytes of the MAC Address are used for packet delivery.
Host Command:
Byte 1 = CCh
Byte 2 = 11h
Transceiver Response:
Byte 1 = CCh
Bytes 2 – 4= 00 – FFh corresponding to the three LSB’s of the destination MAC Address
4.9 EEPROM BYTE READ
Upon receiving this command, a transceiver will respond with the desired data from the address
requested by the OEM Host.
OEM Host Command:
Byte 1 = CCh
Byte 2 = C0h
Byte 3 = Start Address
Byte 4 = Length (01 - 80h)
Transceiver Response:
Byte 1 = CCh
Byte 2 = Start Address
Byte 3 = Length
Byte 4…n = Data at requested addresses
3/23/2006 21
4.10 EEPROM BYTE WRITE
Upon receiving this command, a transceiver will write the data byte to the address specified
but will not echo it back to the OEM Host until the EEPROM write cycle is complete. The
write can take as long as 10ms to complete. Following the write cycle, a transceiver will
transmit the data byte to the OEM Host. Multiple byte EEPROM writes are not allowed.
Caution: The maximum number of write cycles that can be performed is 100,000.
OEM Host Command:
Byte 1 = CCh
Byte 2 = C1h
Byte 3 = Address
Byte 4 = Length (01h)
Byte 5…n = Data to store at Address
Transceiver Response:
Byte 1 = Address
Byte 2 = Length (01h)
Byte 3 = Data byte written by this command
4.11 RESET
The OEM Host issues this command to perform a soft reset of the transceiver (same effect as using the
Reset pin). Any transceiver settings modified by CC Commands (excluding EEPROM writes) will be
overwritten by values stored in the EEPROM.
OEM Host Command:
Byte 1 = CCh
Byte 2 = FFh
Transceiver Response:
Byte 1 = CCh
Byte 2 = FFh
3/23/2006 22
5. Theory of Operation
5.1 HARDWARE INTERFACE
Below is a description of all hardware pins used to control the LT4424.
5.1.1 TXD (Transmit Data) and RXD (Receive Data) (pins 2 and 3 respectively)
The LT4424 accepts 5V TTL level asynchronous serial data in the RXD pin and interprets that data as
either Command Data or Transmit Data. Data is sent from the transceiver to the OEM Host via the TXD
pin. The data must be of the format 8-N-1 (8 data bits, No Parity bits, One stop bit).
5.1.2 Hop Frame (pin 6)
The LT4424 is a frequency hopping spread spectrum radio. Frequency hopping allows the system to
hop around interference in order to provide a better wireless link. Hop Frame transitions logic Low at
the start of a hop and transitions logic High at the completion of a hop. The OEM Host is not required
to monitor Hop Frame.
5.1.3 CTS Handshaking (pin 7)
The LT4424 has an interface buffer size of 256 bytes. If the buffer fills up and more bytes are sent to
the transceiver before the buffer can be emptied, data corruption will occur. The transceiver prevents
this corruption by asserting CTS High as the buffer fills up and taking CTS Low as the buffer is
emptied. CTS On in conjunction with CTS On Hysteresis control the operation of CTS. CTS On
specifies the amount of bytes that must be in the buffer for CTS to be disabled (High). Even while CTS
is disabled, the OEM Host can still send data to the transceiver, but it should do so carefully. Once
CTS is disabled, it will remain disabled until the buffer is reduced to the size specified by CTS On
Hysteresis. The following equation should always be used for setting CTS On, CTS On Hysteresis and
RF Packet Size:
CTS On – CTS On Hysteresis = RF Packet Size
5.1.4 RTS Handshaking (pin 8)
With RTS Mode disabled, the transceiver will send any received packet to the OEM Host as soon as
the packet is received. However, some OEM Hosts are not able to accept data from the transceiver all
of the time. With RTS Mode Enabled, the OEM Host can keep the transceiver from sending it a packet
by disabling RTS (logic High). Once RTS is enabled (logic Low), the transceiver can send packets to
the OEM Host as they are received. Note: Leaving RTS disabled for too long can cause data loss
once the transceiver’s receive buffer fills up.
3/23/2006 23
5.1.5 9600 Baud/Packet Frame (pin 12)
9600_BAUD – When pulled logic Low before applying power or resetting, the transceiver’s serial
interface is forced to a 9600, 8-N-1 (8 data bits, No parity, 1 stop bit) rate. To exit, transceiver must be
reset or power-cycled with 9600_Baud logic High.
9600_BAUD should only be used to recover the radio from an unknown baud rate and should not be
used during normal operation. When 9600_BAUD is pulled logic Low, Broadcast Mode is disabled.
Packet Frame – When enabled in EEPROM, Packet Frame will transition logic Low at the start of a
received RF packet and transition logic High at the completion of the packet.
5.1.6 RSSI (pin 13)
Received Signal Strength Indicator is used by the Host as an indication of instantaneous signal
strength at the receiver. The Host must calibrate RSSI without a RF signal being presented to the
receiver. Calibration is accomplished by following the steps listed below to find a minimum and
maximum voltage value.
1) Power up only one Client (no Server) transceiver in the coverage area.
2) Measure the RSSI signal to obtain the minimum value with no other signal present.
3) Power up a Server. Make sure the two transceivers are in close proximity and measure
the Client’s peak RSSI once the Client reports In Range to obtain a maximum value at full
signal strength.
5.1.7 Wr_ENA(EEPROM Write Enable) (pin 14)
Wr_ENA is a direct connection to the Write Enable line on the EEPROM. When logic Low, the
EEPROM’s contents may be changed. When logic High, the EEPROM is protected from accidental
and intentional modification. It is recommended that this line only be Low when an EEPROM write is
desired to prevent unintentional corruption of the EEPROM.
5.1.8 UP_RESET (pin 15)
UP_RESET provides a direct connection to the reset pin on the LT4424 microprocessor. To guarantee
a valid power-up reset, this pin should never be tied Low on power-up. For a valid power-on reset,
reset must be High for a minimum of 50 μs.
5.1.9 Command/Data (pin 17)
When logic High, transceiver interprets Host data as transmit data to be sent to other transceivers and
their Hosts. When logic Low, transceiver interprets Host data as command data (see Section 4,
Configuring the LT4424).
3/23/2006 24
5.1.10 In Range (pin 20)
The IN_RANGE pin at the connector will be driven logic Low when a Client is in range of a Server on
the same RF Channel and System ID. If a Client cannot hear a Server for 5 seconds, it will drive the
IN_RANGE pin logic High and enter a search mode looking for a Server. As soon as it detects a
Server, the IN_RANGE pin will be driven logic Low. A Server Host can determine which Clients are in
range by the Server’s Host software polling a Client’s Host.
3/23/2006 25
5.2 SOFTWARE PARAMETERS
Below is a description of all software parameters used to control the LT4424.
5.2.1 RF Architecture (Server-Client/Peer-to-Peer)
The Server controls the system timing by sending out regular beacons (transparent to the transceiver
Host), which contain system timing information. This timing information synchronizes the Client radios
to the Server.
Each network should consist of only one Server. There should never be two Servers on the same RF
Channel Number in the same coverage area, as the interference between the two Servers will severely
hinder RF communications.
In Server-Client architecture, the Server communicates with the Clients and the Clients only
communicate with the Server. Enabling Peer-to-Peer Mode will allow all radios on the network to
communicate with each other. Note: All transceivers on the same network must have the same
setting for Peer-to-Peer and there must still be one, and only one, Server present in a Peer-to-Peer
network.
5.2.2 RF Mode
Acknowledge Mode
In Addressed Acknowledge Mode, the RF packet is sent out to the receiver designated by the
Destination Address. Transmit Retries is used to increase the odds of successful delivery to the
intended receiver. Transparent to the OEM Host, the sending transceiver will send the RF packet to
the intended receiver. If the receiver receives the packet free of errors, it will tell the sender. If the
sender does not receive this acknowledge, it will assume the packet was never received and retry the
packet. This will go on until the packet is successfully received or the transmitter exhausts all of its
retries. The received packet will only be sent to the OEM Host if and when it is received free of errors.
In Broadcast Acknowledge Mode, the RF packet is broadcast out to all eligible receivers on the
network. In order to increase the odds of successful delivery, Broadcast Attempts are used to increase
the odds of successful delivery to the intended receiver(s). Transparent to the OEM Host, the sending
transceiver will send the RF packet to the intended receiver. If the receiver detects a packet error, it will
throw out the packet. This will go on until the packet is successfully received or the transmitter
exhausts all of its attempts. Once the receiver successfully receives the packet it will send the packet
to the OEM Host. It will throw out any duplicates caused by further Broadcast Attempts. The received
packet will only be sent to the OEM Host if it is received free of errors.
3/23/2006 26
5.2.3 Random Back Off
Random Back Off – If multiple LT4424 transceivers try to send packets out over the RF at the exact
same time, the packets will collide and will not be received by the intended receiver. In fact, if after a
collision occurs, both transceivers retry at the same time, the retry will also fail. To avoid further
collisions, a transceiver can be programmed to wait a random number of packet times (hops) before
resending its data. The amount of randomness is controlled by this parameter. Keep in mind that
selecting a larger value for Random Back Off will increase the overall latency of the LT4424. The
latency calculation becomes:
Worst Case Latency = 8 ms Hop * # of retries * Maximum Random Value
[multiply by 16 ms if using Full Duplex mode]
Latency is a very important consideration when using a wireless device. The LT4424 has a 256 byte
interface buffer. If, due to latency, the radio cannot send the data out over the RF as fast as data is
coming into the radio over the serial interface, the buffer will eventually fill up. If data continues coming
into the radio once the buffer is full, the buffer will overflow and the new incoming data will be lost. It is
strongly recommended that the radio host monitor the CTS pin to avoid this situation. The transceiver
asserts this pin high as the buffer is filling to signal the OEM Host to stop sending data. The transceiver
will take CTS Low once the buffer becomes less full.
Random Backoff Settings:
• 00h – Wait 1 packet time, then retry (Random Back Off is disabled)
• 01h – Wait 1 – 2 packet times, then retry
• 03h – Wait 1 – 4 packet times, then retry
• 07h – Wait 1 – 8 packet times, then retry
• 0Fh – Wait 1 – 16 packet times, then retry
• 1Fh – Wait 1 – 32 packet times, then retry
• 3Fh – Wait 1 – 64 packet times, then retry
• 7Fh – Wait 1 – 128 packet times, then retry
• FFh – Wait 1 – 256 packet times, then retry
•
5.3 DUPLEX MODE
In Half Duplex mode, the LT4424 will send a packet out over the RF when it can. This can cause
packets sent at the same time by a Server and a Client to collide with each other over the RF. To
prevent this, Full Duplex Mode can be enabled. Though the RF hardware is still technically half
duplex, it makes the radio seem full duplex. This can cause overall throughputs to be cut in half.
Note: All transceivers on the same network must have the same setting for Full Duplex.
Ordering Information
3/23/2006 27
5.4 INTERFACE TIMEOUT/RF PACKET SIZE
Interface timeout, in conjunction with RF Packet Size, determines when a buffer of data will be sent out
over the RF as a complete RF packet based on whichever condition occurs first.
Interface Timeout – Interface Timeout specifies a maximum byte gap in between consecutive bytes.
When that byte gap is exceeded, the bytes in the transmit buffer are sent out over the RF as a
complete packet. Interface timeout is adjustable in 160uS decrements. The actual timeout created by
Interface Timeout is equal to the 2's complement of Interface Timeout times 160uS. The default value
for Interface Timeout is F0H or 2.56ms.
RF Packet Size – When the amount of bytes in the transceiver transmit buffer equals RF Packet Size,
those bytes are sent out as a complete RF packet.
5.5 SERIAL INTERFACE BAUD RATE
This two-byte value determines the baud rate used for communicating over the serial interface to a
transceiver. Table 7 - Baud Rate lists values for some common baud rates. Baud rates below 110
baud are not supported. For a baud rate to be valid, the calculated baud rate must be within ±3% of
the OEM Host baud rate. If the 9600_BAUD pin (Pin 12) is pulled logic Low at reset, the baud rate will
be forced to 9,600. For Baud Rate values other than those shown in Table 7 - Baud Rate, the following
equation can be used:
BAUD = (18.432E+06/(32*desired baud rate))
BaudH= High 8 bits of BAUD (base16)
BaudL = Low 8 bits of BAUD (base16)
Table 7 – Baud Rate
Baud
Rate
BaudL
(42h)
BaudH
(43h)
Minimum Interface Timeout
(58h)
288000 02h 00h FFh
192000 03h 00h FFh
115200 05h 00h FEh
57600 0Ah 00h FDh
38400 0Fh 00h FCh
28800 14h 00h FBh
19200 1Eh 00h F9h
14400 28h 00h F7h
9600 3Ch 00h F2h
4800 78h 00h E5h
2400 F0h 00h CBh
1200 E0h 01h 97h
300 80h 07h 01h
110 74h 14h 01h
Ordering Information
3/23/2006 28
5.2.9Auto Config
The LT4424 has several variables that control its RF performance and vary by RF Mode and RF
Architecture. Enabling Auto Config will bypass the value for these variables stored in EEPROM and use
predetermined values for the given Interface Baud Rate. Auto Config has been optimized for 115200
baud Acknowledge Mode and all lower baud rates. It should only be disabled with recommendation
from Laird Technologies. Below is a list containing some of the variables affected by Auto Config and
their respective values:
Table 8 – Auto Config Parameters
Description2
EEPROM
Address Default
Acknowledge
Mode
47 5 5
48 60 60
4E 8 9
50 FD FD
51 2 2
52 0 0
53 E4 E4
54 5 5
55 50 50
57 7 7
59 4 4
RF Packet Size 5B 40 40
CTS On 5C C0 C0
CTS Hysteresis 5D 80 80
5E 0E 0E
5F 3 3
2 Parameters without a Description are undocumented protocol parameters and should only be modified to a
value other than shown in this table when recommended by Laird Technologies.
Ordering Information
3/23/2006 29
6. Dimensions
The LT4424 measures 1.65”W x 2.65”L. Critical parameters are as follows:
• J1 – 20 pin OEM interface connector (Samtec TMM-110-01-L-D-SM, mates with Samtec
SMM-110-02-S-D)
• MMCX Jack – Antenna connector (Johnson Components P/N 135-3711-822) mates with
any manufacturer’s MMCX plug
Figure 1 – LT4424 with MMCX
Ordering Information
3/23/2006 30
7. Ordering Information
7.1 PRODUCT PART NUMBERS
LT4424-200: LT4424 with 400 mW output power, interface data rates to 288 Kbps, MMCX antenna
connector, -40°C to 80°C
7.2 DEVELOPER KIT PART NUMBERS
SDK-4424-200: Includes (2) LT4424-200 transceivers, (2) RS232 Serial Adapter Boards, (2) 6Vdc
unregulated power supplies, (2) Serial cables, (2) S151FL-5-RMM-2450S dipole
antennas with 5” pigtail and MMCX connector, configuration/testing software,
Integration engineering support
Regulatory Information
3/23/2006 31
8. Regulatory Information
8.1 AGENCY IDENTIFICATION NUMBERS
Part Number US/FCC CANADA/IC
LT4424-200 KQL-4424200 2268C-4424200
8.3APPROVED ANTENNA LIST
Item Part Number Mfg. Type Gain (dBi)
1 MFB24008 Maxrad Omni 8
2 NZH2400-MMCX Laird Technologies Microstrip 1
3 ID2450-RS362 Laird Technologies Panel 9
4 S151FC-L-(132)PX-2450S Nearson Dipole 5
1. The OEM is free to choose another vendor’s antenna of like type and equal or lesser gain as
an antenna appearing in the table and still maintain compliance.
8.38.2 FCC/IC REQUIREMENTS FOR MODULAR APPROVAL
In general, there are two agency classifications of wireless applications; portable and mobile.
Portable – Portable is a classification of equipment where the user, in general, will be within 20 cm of
the transmitting antenna. Portable equipment is further broken down into two classes; within 2.5 cm of
human contact and beyond 2.5 cm. The LT4424 not agency approved for portable applications. The
OEM is required to have additional testing performed to receive this classification. Contact Laird
Technology for more details.
Mobile – Mobile defines equipment where the user will be 20 cm or greater from the transmitting
equipment. The antenna must be mounted in such a way that it cannot be moved closer to the user
with respect to the equipment, although the equipment may be moved.
This equipment has been approved for mobile applications where the equipment should be used at
distances greater than 20 cm from the human body. Operation at distances of less than 20 cm would
require additional RF exposure evaluation, including SAR requirement according to FCC RF Exposure
guideline.
NOTE: This equipment has been tested and found to comply with the limits for a Class B digital device,
pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable protection
against harmful interference in a residential installation. This equipment generates, uses and can
radiate radio frequency energy and, if not installed and used in accordance with the instructions, may
cause harmful interference to radio communications. However, there is no guarantee that interference
will not occur in a particular installation. If this equipment does not cause harmful interference to radio
or television reception, which can be determined by turning the equipment off and on, the user in
encouraged to try to correct the interference by one or more of the following measures:
• Re-orient or relocate the receiving antenna
• Increase the separation between the equipment and the receiver
• Connect the equipment to an outlet on a circuit that is different from that to which the
receiver is connected.
• Consult the dealer or an experienced radio/TV technician for help.
Regulatory Information
3/23/2006 32
8.3 OEM EQUIPMENT LABELING REQUIREMENTS
WARNING: The OEM must ensure that FCC labeling requirements are met. This includes a clearly visible
label on the outside of the OEM enclosure specifying the appropriate Laird Technology FCC identifier for
this product as well as the FCC notice below. The FCC identifiers are listed above.
Contains FCC ID:KQL-4424200
This enclosed device complies with Part 15 of the FCC Rules, Operation is subject to the following two
conditions: (1) This device may not cause harmful interference, and (2) This device must accept any
interference received, including interference that may cause undesired operation
Label and text information should be in a size of type large enough to be readily legible, consistent with
the dimensions of the equipment and the label. However, the type size for the text is not required to be
larger than eight point.
8.4 ANTENNA REQUIREMENTS
To reduce potential radio interference to other users, the antenna type and gain should be chosen so
that the equivalent isotropically radiated power (e.i.r.p.) is not more than that permitted for successful
communication.
WARNING: This device has been tested with an MMCX connector with the above listed antennas.
When integrated into the OEM’s product, these fixed antennas require professional installation
preventing end-users from replacing them with non-approved antennas. Any antenna not listed in the
above table must be tested to comply with FCC Section 15.203 for unique antenna connectors and
Section 15.247 for emissions. Contact Laird Technology for assistance.
Caution: Any changes or modifications not expressly approved by Laird Technology could void the
user’s authority to operate the equipment.
8.5 WARNINGS REQUIRED IN OEM MANUALS
WARNING: This equipment has been approved for mobile applications where the equipment should
be used at distances greater than 20cm from the human body. Operation at distances of less than
20cm is strictly prohibited and requires additional SAR testing.