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TAPR PIC-E Manual May 1999 Page 1 of 16

TAPR PIC-E

™

Tucson Amateur Packet Radio

8987-309 E. Tanque Verde Rd #337

Tucson, Arizona • 85749-9399

Office: (940) 383-0000 • Fax: (940) 566-2544

Internet: TAPR@TAPR.ORG • www.tapr.org

Non-Profit Research and Development Corporation

TAPR PIC-Encoder

Reproduction or translation of any part of this work beyond that

permitted by sections 107 or 108 of the 1976 United States

permission of Tucson Amateur Packet Radio Corporation is

unlawful except as noted below. Requests for permission to copy

or for further information should be addressed to Tucson Amateur

Packet Radio Corporation. Except as noted above, permission

is hereby granted to any nonprofit group or individual to

reproduce any portion of this document provided that: the

reproduction is not sold for profit; the intent of the reproduction

is to further disseminate information on Amateur Packet Radio;

the reproduction is not used for advertising or otherwise

promoting any specific commercial product; full credit is given

to Tucson Amateur Packet Radio Corporation (including address)

as the original source of information; and Tucson Amateur Packet

Radio Corporation is notified in writing of the reproduction.

The information contained in this document has been carefully checked and is believed to be entirely reliable.

However, no responsibility is assumed for inaccuracies. Tucson Amateur Packet Radio Corporation (TAPR) reserves

the right to make changes in any products to improve reliability, function or design without obligation to purchasers

of previous equipment. TAPR does not assume any liability arising out of the application or use of any product or

circuit described herein; neither does it convey license under its patent rights or the rights of others.

Introduction

The TAPR PIC-Encoder (PIC-E) is a general-purpose

packet radio encoder based on the Microchip, Inc.

PIC16F84 PIC microcontroller. The PIC-E was

designed to provide a generic interface between the

digital world (in the form of serial data streams) and

the amateur packet radio world (in the form of AX.25

packets) and is fully programmable by the user. For

example, the user can program the PIC

microcontroller to take serial data from a GPS receiver

or weather station and transmit it as formatted packet

frames. Virtually any data that can be provided to

the device as a serial input stream can be reformatted

and transmitted as 1200 bps packet radio.

The PIC-E is based on two chips: a Microchip, Inc.

PIC16F84 microcontroller and a MX-COM, Inc.

MX614 Bell 202 modem chip. The PIC16F84 is a

general purpose “computer on a chip” that can be

programmed and reprogrammed by the end user. The

PIC-E has an on-board PIC programmer. It is only

necessary to connect a short serial cable between the

PIC-E and a PC serial port and run the appropriate

programming software.

The PIC can be programmed to receive an incoming

data stream and reformat it for transmission as AX.25

frames. The PIC sends the formatted data to the

MX614 that generates tones necessary to transmit 1200

bps packet over the radio’s audio channel. The MX614

contains an energy detect circuit. Receive audio can

be routed to the MX614 and it can determine whether

the channel is in use and send this information back

to the microcontroller. As a result, no additional VOX

or carrier detect circuitry is required to prevent the

PIC-E from colliding with other users on the channel.

The MX614 can detect both digital signals and voice,

so it is suitable for applications where digital and

audio signals are mixed on the same frequency.

The PIC-E is an open system and it is hoped that many

hams will use it as a platform for developing new

and innovative applications. Almost any application

that involves point to point or point to multi-point

Introduction 1

Acknowledgments 2

Parts List 2

Construction Notes 3

Construction 4

Operation 8

Programming the PIC-E 8

Radio and Mic Interfacing 10

Serial Device Interfacing 13

Applications 13

Jumpers 14

Troubleshooting 15

Schematic 16

Page 2 of 16 May 1999 TAPR PIC-E Manual

Acknowledgements

The Tucson Amateur Packet Radio PIC-Encoder Kit

was made possible by the pioneering efforts of (in

alphabetical order):

Steve Bible, N7HPR Project Manager

Joe Borovetz, WA5VMS Parts Liaison

Steve Dimse, K4HG Conceptual Design

Byon Garrabrant, N6BG Programmer,

Conceptual Design

John Hansen, W2FS Programmer,

Conceptual Design

Greg Jones, WD5IVD TAPR Project Liasion

John Koster, W9DDD PCB Design

Dan Welch, W6DFW Conceptual Design,

Documentation

transmission of low-density data is a candidate for

PIC-E development. To write applications for the

PIC-E you will need to learn how to develop PIC

firmware. Don’t worry, it is not all that difficult. Most

of what you will need to get started is readily available

at little or no cost. The software to get started in PIC

development is available for free at

http://www.microchip.com. A discussion of the

basics of getting started in PIC programming can be

found in an article by W2FS in the October 1998 issue

of QST. The Proceedings of the 1998 TAPR/ARRL

Digital Communications Conference contains

information on how to implement AX.25 UI frames

in PIC microcontroller. While the 16F84 contains only

1K of program space, it turns out that this provides

enough room not only to decode incoming serial data

and construct outgoing packets, but to do a significant

amount of processing and reformatting of the data as

well.

As PIC-E programs are developed they will be

displayed or linked from the TAPR PIC-E web site

located at http://www.tapr.org/taprf/html/

Fpice.html. If you’ve created a project and would like

to display or link to it, contact TAPR at tapr@tapr.org.

Updated documentation can be found at

http://www.tapr.org/taprf/html/Fpice.html or

ftp://ftp.tapr.org/picsig/docs/.

Contributed files can be found at

ftp://ftp.tapr.org/picsig/software/. Files can be

anonymously uploaded to

ftp://ftp.tapr.org/picsig/upload/.

PIC-E is discussed on the PIC special interest group.

You can join PIC SIG via the web at

http://www.tapr.org/cgi-bin/lyris.pl?join=picsig.

PARTS LIST

The parts list is organized by quantity and part type.

Verify that all parts are present by checking in the

space [ ] provided as you locate the part in the list.

You may wish to take this opportunity to sort the parts

into a compartmented container such as an egg carton

or muffin tin as you inventory them. This will aid

you in kit building.

Resistors (1/4 w, 5% Carbon Film):

[ ] (4) 1.2K ohm (brown-red-red-gold)

R11,R14,R15,R18

[ ] (3) 2.2K ohm (red-red-red-gold) R4,R5,R7

[ ] (9) 10K ohm (brown-black-orange-gold)

R3,R9,R10,R13,R16,R17,R19,R20,R21

[ ] (2) 22K ohm (red-red-orange-gold) R2,R6

[ ] (3) 100K ohm (brown-black-yellow-gold)

R1,R8,R12

Resistor, (Trimpot, 25-Turn)

[ ] (1) 10K ohm Trimpot (103) V1

Capacitors

Capacitors may be marked in various ways. The

typical markings are listed but may vary. Find all that

match and the remaining ones, if any, should become

apparent by elimination.

Mylar or Monolithic

[ ] (5) 0.1 uf (104) C2,C5,C6,C7,C8

Electrolytic or Tantalum

[ ] (2) 1uF (105) C3,C4

[ ] (1) 100 uf C1

Diode

[ ] (1) 1N34 Germanium Diode D6

[ ] (3) 1N4002 Silicon Diode D7,D9,D11

[ ] (2) 1N4148 Silicon Diode D1,D10

[ ] (1) 1N5231BDICT-ND 5.1V Zener Diode D2

Light Emitting Diodes

[ ] (1) Green T1 D8

[ ] (2) Yellow T1 D3,D4

[ ] (1) Red T1 D5

Integrated Circuits

NOTE: Do not handle the ICs at this time! Carefully

remove the black foam carrier with ICs from the bag

and verify the ICs against this list. Do not touch the

ICs!

[ ] (1) PIC16F84 U1

[ ] (1) MX614 U3

TAPR PIC-E Manual May 1999 Page 3 of 16

Transistors

[ ] (1) 2N3904 NPN Transistor Q1

Voltage Regulators

[ ] (1) 7805 U2

Ceramic Resonators

Ceramic Resonators look very much like a dipped

capacitor, but have three leads.

[ ] (1) 3.58 MHz X2

[ ] (1) 10 MHz X1

IC Sockets

[ ] (2) 16-pin DIP Socket U3, J3

[ ] (1) 18-pin DIP Socket U1

[ ] (1) 16-pin Machine Tooled DIP Socket J3

Connectors

[ ] (3) 1x2-pin male header

[ ] (2) 1x3-pin male header

[ ] (3) 1x8-pin male header (or (1) 1x8 and (1) 2x8)

[ ] (12) 2-pin Jumper, Push-On

[ ] (1) DB9 Female PCB right angle mount

[ ] (1) DB9 Male PCB right angle mount

[ ] (2) 8-pin RJ-45 jack PCB right angle mount

[ ] (1) 2.1 mm Coaxial Jack

[ ] (1) 2.1 mm Coaxial Plug

Miscellaneous

[ ] (1) Printed Circuit Board

[ ] (1) Assembly Manual (this document)

[ ] (1) Cable Assembly with RJ-45 connectors

[ ] (2) Miniture Toggle Switches

[ ] (4) 4-40 x 3/8” screws

[ ] (4) 4x40 nuts

[ ] (1) Solid wire

CONSTRUCTION NOTES

You are now ready to begin construction of the PIC-

Encoder. Follow standard construction practices

when building the unit.

Use a temperature-controlled, fine-tipped soldering

iron of relatively low wattage (25 watts maximum,

15 watts is ideal) and a good quality 60/40 or 63/37

rosin-core solder for construction. Keep the tip of your

soldering iron bright and clean, wiping it frequently

on a wet rag or sponge. Make solder joints carefully,

but swiftly. Prolonged heat on a PC board pad can be

as disastrous as it can ruin the PC board. Two to three

seconds should be enough time to apply heat to any

joint. Due to the proximity of some of the traces on

the PC board, solder bridges are a very distinct

possibility. Following these points could eliminate

several hours of troubleshooting (or worse). This is

good practice when working on any kit.

You will need small flush or semi-flush cutting pliers

and small-tipped long nosed pliers. A magnifying

glass may prove helpful to identify the values of the

small components.

Pay careful attention to the directions that follow. Pay

close attention to the following:

1) Read this entire document prior to starting

construction of your kit.

2) Identifying the pins on headers - Pin 1 is identified

by the square pad on silk-screen.

Electrostatic Protection

The Integrated Circuits are susceptible to static

discharge. Observe anti-static precautions when

assembling the PIC-Encoder.

Page 4 of 16 May 1999 TAPR PIC-E Manual

CONSTRUCTION

Refer to the layout diagram for clarification of parts

placement.

Resistors

Resistors have a lead spacing of 0.4" and should lie

flat on the PC board. You may wish to use a lead

former to pre-form the resistor leads for neatest

appearance.

Install the following resistors:

[ ] R14 1.2K ohm (brown-red-red-gold)

[ ] R17 10K ohm (brown-black-orange-gold)

[ ] R18 1.2K ohm (brown-red-red-gold)

[ ] R11 1.2K ohm (brown-red-red-gold)

WARNING! Be careful when clipping leads, as they

have a tendency to fly towards your eyes! Take

appropriate precautions (grasp leads and wear eye

protection).

[ ] Solder and clip the leads (8 total)

[ ] R1 100K ohm (brown-black-yellow-gold)

[ ] R3 10K ohm (brown-black-orange-gold)

[ ] R10 10K ohm (brown-black-orange-gold)

[ ] R16 10K ohm (brown-black-orange-gold)

[ ] R15 1.2K ohm (brown-red-red-gold)

[ ] Solder and clip the leads (10 total)

[ ] R13 10K ohm (brown-black-orange-gold)

[ ] R7 2.2K ohm (red-red-red-gold)

[ ] R5 2.2K ohm (red-red-red-gold)

[ ] Solder and clip the leads (6 total)

[ ] R6 22K ohm (red-red-orange-gold)

[ ] R4 2.2K ohm (red-red-red-gold)

[ ] R8 100K ohm (brown-black-yellow-gold)

[ ] R2 22K ohm (red-red-orange-gold)

[ ] Solder and clip the leads (8 total)

[ ] R12 100K ohm (brown-black-yellow-gold)

[ ] R9 10K ohm (brown-black-orange-gold)

CAUTION! Diode D6 and D9 are next to resistor R9.

Make certain that you install resistor R9 in its proper

place.

[ ] R19 10K ohm (brown-black-orange-gold)

[ ] R20 10K ohm (brown-black-orange-gold)

[ ] R21 10K ohm (brown-black-orange-gold)

[ ] Solder and clip the leads (10 total)

Now check your work. All leads should be soldered.

There should be no solder bridges or cold solder

connections.

[ ] OK so far.

This completes the resistor installation. You should

have no remaining resistors.

[ ] No resistors remaining.

Diode

Diodes are polarity sensitive devices. Diodes are

mounted flat near the surface of the board like the

resistors previously installed. The cathode end of the

diode is banded and corresponds to the banded silk-

screen legend on the PCB.

Install the following diodes:

[ ] D1 1N4148

[ ] D2 1N5231 Zener

[ ] Solder and clip the leads (4 total)

[ ] D7 1N4002

[ ] D6 1N34

[ ] D9 1N4002

[ ] Solder and clip the leads (6 total)

[ ] D10 1N4148

[ ] D11 1N4002

[ ] Solder and clip the leads (4 total)

Now check your work. All leads should be soldered.

There should be no solder bridges or cold solder

connections.

[ ] OK so far.

This completes the diode installation. You should have

no remaining diodes.

[ ] No diodes remaining.

TAPR PIC-E Manual May 1999 Page 5 of 16

IC Sockets

NOTE: If any socket pins are bent, carefully straighten

them with a pair of long-nose pliers before assembly.

Some types of IC sockets have crimps in the pins to

hold them in place when automatic wave soldering

is performed. These sockets may be tricky to install if

you are not familiar with them. If your kit contains

these sockets, you may want to straighten the pins

before attempting to insert them into the PC board.

When installing IC sockets double check to ensure

that the socket is seated properly against the board

with the notch matching the silk-screen. Pin 1 (nearest

the socket notch) has a square solder pad. Be sure

that all IC socket pins are showing on the solder side

of the board. Next, tack-solder two diagonally

opposite corners first (such as pins 1 and 8 on a 14-

pin socket).

Then solder the remaining pins of that socket before

proceeding to the next one. If you find a socket is

difficult to install, remove it and double-check for a

bent pin.

CAUTION! Take care to avoid solder bridges!

NOTE: Do not solder the 16-pin Machine IC Socket

to the PCB. It will be plugged into the socket J3 as a

programming header later.

Install the following IC sockets:

[ ] U1 18-pin

[ ] U3 16-pin

[ ] J3 16-pin

Now check your work. All leads should be soldered.

There should be no solder bridges (a blob of solder

that shorts two adjacent soldered connections) or cold

(gray and/or grainy looking) solder connections.

[ ] OK so far.

This completes the IC socket installation. You should

have one 16-pin Machined IC sockets remaining.

[ ] One 16-pin Machined IC socket remaining.

Trimpots

Align the trimpot according to the silkscreen.

Install the trimpot:

[ ] V1 10K ohm

[ ] Solder and clip the leads (3 total)

Capacitors

All capacitors should be mounted as nearly flush to

the board surface as practical without stressing the

leads.

Install the following capacitors:

[ ] C2 0.1 uF (104)

[ ] C5 0.1 uF (104)

[ ] C6 0.1 uF (104)

[ ] C7 0.1 uF (104)

[ ] C8 0.1 uF (104)

[ ] Solder and clip the leads (10 total)

Electrolytic and Tantalum capacitors are polarized.

The positive lead goes in the hole on the board marked

with a “+”. Be careful! Typically the negative lead is

marked and sometimes the positive lead is marked.

[ ] C3 1 uF

[ ] C4 1 uF

[ ] Solder and clip the leads (4 total)

[ ] C1 100 uF

[ ] Solder and clip the leads (2 total)

Now check your work. All leads should be soldered.

There should be no solder bridges or cold solder

connections.

[ ] OK so far.

This completes the capacitor installation. You should

have no remaining capacitors.

[ ] No capacitors remaining.

Page 6 of 16 May 1999 TAPR PIC-E Manual

Ceramic Resonators

Ceramic resonators are not polarity sensitive.

Install the following ceramic resonators:

[ ] X1 10 MHz

[ ] X2 3.58 MHz

[ ] Solder and clip the leads (6 total)

Transistor

NOTE: Transistors are polarized components. Match

the body of the transistor with the silk-screened

outline and carefully bend the transistor leads to

match the hole pattern on the PC board. The bottom

of the body of the transistor should not be more than

1/4" above the PC board.

[ ] Q1 2N3904 NPN Transistor

[ ] Solder and clip the leads (3 total)

Voltage Regulator

NOTE: Voltage regulators are polarized components.

Match the body of the voltage regulator with the silk-

screened outline and carefully bend the leads to match

the hole pattern on the PC board. The bottom of the

body of the voltage regulator should not be more that

1/4” above the PC board.

NOTE: position the 7805 with the heatsink positioned toward the

edge of the PCB

[ ] U2 7805

[ ] Solder and clip the leads (3 total)

Male Headers

The 2-, 3-, and 8-pin male headers will be installed

next. The plastic body of the part should rest flush

with the top surface of the PC board. The short end of

the pins goes into the PC board, the long end sticks

up.

WARNING! Do not hold these parts with your

fingers as they quickly get very hot while soldering

in place.

Place a 2-pin jumper on the header to insulate your

finger from the pins, hold the header in place and

tack solder one pin. Check for proper alignment. If

alignment is off, you can reheat the one pin to adjust.

Once the alignment is correct, solder the rest of the

pins and then reflow (reheat) the first pin you

soldered.

[ ] JP1 1x2 pin

[ ] JP3 1x2 pin

[ ] JP4 1x2 pin

[ ] JP2 1x3 pin

[ ] JP5 1x3 pin

Place two or more 2-pin jumpers on the three 1x8 male

headers (between J5 and J6 and from J6 to J4) to

interlock them together and then tack solder. Check

for proper alignment. Once alignment is correct,

solder the rest of the pins.

NOTE: Your kit may contain (1) 1x8 header and (1)

2x8 header. Follow the same general procedure.

Solder them side-by-side using two 2-pin jumpers to

interlock and align them for soldering.

[ ] J4 1x8 pin

[ ] J5 1x8 pin

[ ] J6 1x8 pin

Connectors

CAUTION! Soldering the coaxial power connector

is a bit tricky because of the large mounting holes.

[ ] P3 Coaxial power connector

Install the DB-9 connectors in their respective

locations. First, secure the connector using two screws

and nuts. Next, solder the leads.

[ ] P1 DB-9 male (GPS)

[ ] P2 DB-9 female (Program)

Gently rock the RJ-45 connectors until they snap into

place and solder the leads.

[ ] J1 RJ-45 connector

[ ] J2 RJ-45 connector

Switches

Install two miniature toggle switches. Position them

according to the silkscreen and solder the leads and

body mounting pins.

[ ] SW1

[ ] SW2

TAPR PIC-E Manual May 1999 Page 7 of 16

Light Emitting Diodes (LEDs)

LEDs are polarized components. The flat side on the

body and the shorter lead of the two identifies the

cathode lead. Insert the LED according to the silk-

screen outline.

[ ] D8 Green LED (Power)

[ ] D3 Yellow LED (Valid)

[ ] D5 Red LED (PTT)

[ ] D4 Yellow LED (Active)

[ ] Solder and clip the leads (8 total)

Jumpers

Install push-on jumpers in the following locations:

[ ] JP2 – N

[ ] JP3

[ ] JP4

[ ] JP5 – SW2

[ ] Eight between J4/J6

Voltage Checks

It is best to do a preliminary voltage check before

installing the Integrated Circuits. This is a relatively

easy check to make and can save you headaches later

but first you need to supply power to the PIC-E.

The PIC-E can be powered via two methods, either

from an external power supply or batteries. The

onboard 7805 voltage regulator can accept an input

voltage from 7 to 20 volts. The output of the 7805 is

+5 volts at 1Amp. A power adapter (wall wart) that

supplies 9 or 12 volts DC rated at least 100 mA with a

2.1 mm coaxial connector will work fine. Make certain

that the center conductor is positive. Batteries can

also power the PIC-E. A 9 volt transistor battery works

great.

Power can be applied to the PIC-E via two methods,

either through the 2.1 mm coaxial power connector

P3 or B1 (two solder holes near P3). As mentioned

before, the center pin of P3 is positive. Observe the

polarity markings when connecting power to B1.

[ ] Apply 7 to 20 Volts DC power to P3 or B1.

[ ] The green power LED should light.

NOTE: JP4 must be installed.

Measure +5VDC at the following locations:

[ ] JP4

[ ] U1 pin 14

[ ] U3 pin 16

If the above measurements are incorrect, carefully

inspect the PIC-E for solder bridges, parts placement,

polarity of parts, anything that looks unusual. Use

the PIC-E schematic to trace the flow of power

through the PIC-E to locate and correct the problem.

If the above measurements are correct, proceed to the

next section.

Integrated Circuits

Observing static precautions and polarity, install the

following ICs in their sockets. Pay particular attention

to aligning the notch of the IC with the socket:

WARNING! Remove all power before installing ICs.

[ ] Remove power from the PIC-E.

Install the following ICs:

[ ] U1 PIC16F84

[ ] U3 MX614

Page 8 of 16 May 1999 TAPR PIC-E Manual

OPERATION

The PIC-E is a flexible and versatile device. There are

several ways to interface and configure it. The PIC-E

can be interfaced to a serial device, such as a GPS

receiver or weather station, a microphone and radio.

A typical PIC-E installation will use a serial device

and a radio. Interfacing a microphone to the PIC-E is

not mandatory.

Now that your PIC-E is fully assembled, it’s time to

learn how to program and interface it to radios and

serial devices. First, you’ll learn how to program the

PIC-E with a small diagnostic program that will test

various functions. Once these are completed, you’ll

learn how to interface the PIC-E to radios and serial

devices.

Programming the PIC-E

The onboard serial programmer on the PIC-E receives

power from the serial port.

WARNING! WARNING! WARNING!

DO NOT power the PIC-E during programming.

Serial ports differ from computer to computer and

there may not be sufficient voltage to power the

PIC-E during programming. If you have difficulty

programming the PIC, remove the jumper on JP4

during programming. This will remove

programming power from the rest of the PIC-E

circuitry during programming.

NOTE: JP4 must be installed during normal PIC-E

operation. If you forget to install JP4 prior to operating

the PIC-E, the power LED will not light when power

is applied.

The programming circuitry on the PIC-E is based on

the Ludipipo programmer designed my Ludwig

Catta. John Hansen, W2FS, wrote about this

programmer in an article in the October 1998 QST,

"Using PIC microcontrollers in Amateur Radio

projects." There are several software programs that

interface to the Ludipipo circuitry. Two have been

tested on the PIC-E: PiX and PicProg. PiX is a DOS

based programmer and PicProg is Windows based.

For this example we’ll use PicProg. John illustrates

how to use PiX in his QST article.

Loading PicProg onto your computer

PicProg is a Windows PIC16C84 programmer that can

program the PIC-E. Unzip the picprg06.zip file

into a suitable directory on your computer. Run

PicProg and set the communications port by selecting

Setup|Com Port from the menu bar. The following

window will pop up:

Click on the radio button corresponding to the

computer comm port connected to the PIC-E.

Connect a serial cable to the PIC-E Program P2 jack

and your computer’s serial port.

Next, open the diagnostic hex file picediag.hex

by selecting File|Open File from the menu bar. The

following window will pop up:

TAPR PIC-E Manual May 1999 Page 9 of 16

Browse to the directory containing picediag.hex and click OK. PicProg is now ready to program the

PIC-E.

Check the box next to PWRTE to select Power-up Timer option of the PIC. To program the PIC-E click on the

Program Chip button. The status line in the lower left will indicate the programming status. The power

LED on the PIC-E will glow slightly while programming is in progress. In about a minute, if all goes well, the

status line will report "Chip programmed" when completed.

In case of problems, check the serial cable and connections. Try a shorter (or shorten) the cable. Try removing

jumper JP4. This removes power to the surrounding circuitry and applies it only to the PIC. The PIC-E

programmer uses the serial port for power and not all serial ports are the same from computer to computer.

If the power output is low, the programming of the PIC can fail. Remember to reinstall JP4 when programming

is complete.

Run diagnostic

The diagnostic program tests the MX614 modem chip and lights the VALID LED. Place both toggle switches

to the right. Apply power to the PIC-E. The switch functions are:

Mode Switch right – Off

Mode Switch left – Toggle tones at 1200 bps and assert PTT

Option Switch right – Off

Option Switch left – light VALID LED

[ ] Apply power to the PIC-E.

[ ] Move the Option Switch to the left. The VALID LED should light.

[ ] Without a radio connected to the PIC-E, move the Mode Switch to the left, the PTT LED should light.

[ ] Move both toggle switches to the right.

[ ] Remove power to the PIC-E.

Page 10 of 16 May 1999 TAPR PIC-E Manual

Radio and Microphone Interfacing

This section discusses interfacing the PIC-E to a radio

and microphone.

[ ] Install the 16-pin machine tooled DIP socket in J3.

J1 Microphone/J2 Radio Jacks

Microphone jack J1 and Radio jack J2 are 8-pin RJ-45

jacks. Pins 1 though 8 of J1 and J2 correspond to pins

1 through 8 of J3 (see Figure 1). The pin-out of J1 and

J2 is:

J3/J4/J5/J6 – Microphone/PTT Programming Header

Jumpers J3/J4/J5/J6 configure your microphone and

radio to the PIC-E. A microphone connects to Jack J1

(RJ-45) and a radio to J2 (RJ-45). Figure 1 illustrates

the signal flow through the PIC-E.

Programming Header J3 is a machined-tooled 16-pin

DIP socket that plugs into DIP socket J3. The user

inserts wire jumpers between one side of the socket

(pins 1-8) to the other side (pins 9-16) connecting

signals between the microphone, radio, and the PIC-

[ ] Using Table 1 on the next page, write in the

signal name corresponding to the pin number

of your radio’s microphone jack in right-hand

column.

[ ] Draw a line between the microphone jack

signal name in the right-hand column to the

corresponding PIC-E signal name in the left-

hand column. These lines will become wire

jumpers on the DIP programming header J3.

Mandatory signals (indicated by * on Table 1)

to be connected to the PIC-E are:

A cable assembly with a RJ-45 plug on each end is

included in the kit. If you are interfacing the PIC-E to

a radio that already has a RJ-45 connector, connect

the cable between the PIC-E and radio. If the radio

you are interfacing to does not have a RJ-45 jack, you

can cut the cable to length and solder on a microphone

connector that mates to your radio.

Figure 1 – Signals Interface

12345678

Looking into RJ-45 jack

RJ-45

Pins

1-8

Pins

9-10

RJ-45

Left

Center

Right

RAD_PTT

Radio

RAD_PTT

RXA

MIC_AUDIO

RADIO_GND

Microphone

MIC_AUDIO

MIC_PTT

MIC_GND

PIC-E

9 - MIC_PWR

10 - RADIO_GND

11 - MIC_PTT

12 - RXA

13 - MIC_AUDIO

14 - MIC_GND

15 - +5

16 - GND

TAPR PIC-E Manual May 1999 Page 11 of 16

- Ground (either Radio_Ground,

MIC_Ground, or Ground)

- Mic_Audio (PIC-E TX Audio to Radio)

- MIC_PTT (Microphone Push-to-Talk)

Optional signals are:

- +5V (PIC-E voltage to user equipment,

no greater than 50 mA)

- RXA (Radio speaker audio to PIC-E for

data/carrier sense)

- MIC_Power (Radio voltage to power

PIC-E)

[ ] Cut and strip the solid wire supplied in the kit

for jumpers between the pin holes of the

machined-tooled DIP socket corresponding to

the lines drawn on Table 1.

PTT Selection

Jumpers on the eight rows of pins on J4 and J6 pass

through microphone signals from J1 (MIC IN) to J2

(RADIO). The user installs seven 2-pin jumpers to

pass all microphone signals with the exception of Push

to Talk (PTT). The pin corresponding to PTT is

jumpered between J4 and J5 using a 2-pin connector.

This action disconnects the PTT signal between the

microphone and radio and allows the PIC-E to control

PTT.

[ ] Find the pin number of the microphone PTT.

Pin number __________.

[ ] Remove the 2-pin jumper across J4/J6

corresponding to the PTT pin.

[ ] Install the 2-pin jumper across J4/J5

corresponding to the PTT pin.

Handie-Talkie Interfacing

If you plan to interface a handie-talkie to the PIC-E

and require a resistance inline with the PTT line (such

as Yaesu and Icom radios), remove jumper JP3. This

will insert a 2.2K ohm resistance inline with the

PIC-E RAD_PTT signal. Figure 3 shows a typical

handie-talkie interface for Alinco, ICOM, Standard,

Tandy, and Yaesu radios.

Figure 2 – Programming Jumpers

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9)*(dnuorG8

01V5+7

11dnuorGCIM6

21)*(oiduACIM5

31AXR4

41)*(TTPCIM3

51dnuorGoidaR2

61rewoPCIM1

Table 1 - Jumper J3

Figure 3. Typical HT Interface

J5 J6 J4

RXA

GND

MIC_AUDIO

PTT

EAR

MIC

JP3

Page 12 of 16 May 1999 TAPR PIC-E Manual

Setting Deviation

Setting the PIC-E audio output sets the deviation of

the packet signal. This is an important setting. If the

audio output is too low the receiving station will not

decode packets. If the audio output is too high the

radio will be over-deviated and cause splatter.

You can set the deviation via one of three methods:

manual, voltage measurement, or deviation meter.

Manual

If you do not have access to an oscilloscope, service

monitor, or deviation meter, you can set the deviation

using manual method with good results. Set the

deviation as follows:

[ ] Connect the PIC-E to your radio.

[ ] Attach a dummy load to the radio’s antenna

connection.

[ ] Set the PIC-E audio output to minimum by

turning V1 fully counter-clockwise.

[ ] Power up the PIC-E with the diagnostic pro-

gram loaded.

[ ] Use a second radio to monitor the output of

the transmitter connected to the PIC-E.

[ ] Set the MODE SW to the right. PTT LED

should light and the radio starts transmitting.

[ ] Slowly turn V1 clockwise. Tones should be

heard on the monitoring radio.

[ ] Continue to turn V1 clockwise until the vol-

ume of the tone stops changing. Turn V1

slightly counter-clockwise.

[ ] Set the MODE SW to the left.

[ ] Remove power to the PIC-E.

This completes deviation setting. Skip to Serial Device

Interfacing.

Voltage Measurement

If you have access to an oscilloscope or peak-to-peak

measuring voltmeter, set the deviation as follows:

[ ] Connect the oscilloscope to the MIC_AUDIO

line of the PIC-E.

[ ] Set the PIC-E audio output to minimum by

turning V1 fully counter-clockwise.

[ ] Power up the PIC-E with the diagnostic pro-

gram loaded.

[ ] Set the MODE SW to the right. PTT LED

should light and the radio starts transmitting.

[ ] Slowly turn V1 clockwise.

[ ] Set the MIC_AUDIO output to 850 millivolts,

peak to peak.

[ ] Set the MODE SW to the left.

[ ] Remove power to the PIC-E.

This completes deviation setting. Skip to Serial Device

Interfacing.

Deviation Meter

If you have or have access to a service monitor or

deviation meter such as the AEA (now Timewave)

DM-1, set the deviation as follows:

[ ] Connect the output of the radio to a service

monitor or deviation meter.

[ ] Set the PIC-E audio output to minimum by

turning V1 fully counter-clockwise.

[ ] Power up the PIC-E with the diagnostic pro-

gram loaded.

[ ] Set the MODE SW to the right. PTT LED

should light and the radio starts transmitting.

[ ] Slowly turn V1 clockwise.

[ ] Set deviation to 3.5 – 4.0 kHz.

[ ] Set the MODE SW to the left.

[ ] Remove power to the PIC-E.

This completes deviation setting.

TAPR PIC-E Manual May 1999 Page 13 of 16

Serial Device Interfacing

The PIC-E can be interfaced to any serial device such

as GPS receivers or weather stations. Since the PIC-E

is fully programmable, you can parse the serial stream

into any format you desire and output it via the radio

port at Bell 202 tones.

P1 is configured as a Data Terminal Equipment (DTE)

serial port (i.e. computer port). Any Data

Communications Equipment (DCE) device can

connect pin-for-pin to the port. The pin outs are (labels

are with respect to the PIC-E):

Applications

That completes the interfacing of the PIC-E. All that

remains is to program the PIC-E for the application

of interest. You can choose to load an already written

program or write one of your own. As PIC-E

programs are developed they will be displayed or

linked from the TAPR PIC-E web site located at

http://www.tapr.org/taprf/html/Fpice.html. If

you’ve created a project and would like to display or

link to it, contact TAPR at tapr@tapr.org.

Updated documentation can be found at

http://www.tapr.org/taprf/html/Fpice.html or

ftp://ftp.tapr.org/picsig/docs/.

Contributed files can be found at

ftp://ftp.tapr.org/picsig/software/. Files can be

anonymously uploaded to

ftp://ftp.tapr.org/picsig/upload/.

PIC-E is discussed on the PIC special interest group.

You can join PIC SIG via the web at

http://www.tapr.org/cgi-bin/lyris.pl?join=picsig.

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2)DXR(nIlaireS

3)DXT(tuOlaireS

4)RTD(ydaeRlanimreTataD

5dnuorG

For normal serial connections, configure the following

jumpers:

JP1 – open

JP2 – jumper across N

A Delorme Tripmate GPS receiver can be interfaced

to the PIC-E by placing jumpers in the following

locations:

JP1 – closed

JP2 – jumper across T

Page 14 of 16 May 1999 TAPR PIC-E Manual

JUMPERS

The following tables summarize the jumper selections

on the PIC-E.

JP1, JP2 – Tripmate Selection

Delorme’s Tripmate GPS receiver can be used with

the PIC-E. Install jumpers JP1 and JP2 according to

the table below. JP1 will apply +5VDC to pin 4 of P1

and JP2 will jumper pins 2 and 3 together. To

configure P1 for normal serial operations, install

jumpers JP1 and JP2 according to the table below.

JP5 – MX614 Receive/Option Switch SW2

The PIC16F84 microcontroller has a finite number of

I/O pins. Jumper JP5 allows you to select whether

you want PIC port RB4 (pin 10) to be configured to

receive digital data from the MX614 modem chip or

switch SW2.

1PJ2PJ

laireSlamroNNnepO

etampirTTdesolC

JP3 – Handi-Talkie

JP3 provides a 2.2 Kohm resistor in series with the

PTT line. If a handie-talkie is interfaced to the PIC-E

and resistance is needed inline with PTT, JP3 should

be open. If resistance is not need, JP3 should be

jumpered (closed).

3PJ

lamroNdesolC

rotsiseRnepO

JP4 – Programming

The onboard serial programmer of the PIC-E receives

its power from the serial port. It is not necessary to

power the PIC-E during programming. However,

serial ports differ from computer to computer and

there may not be sufficient voltage to power the PIC-

E during programming. If you have difficulty

programming the PIC, remove the jumper on JP4

during programming. This will allow you to remove

programming power from the rest of the PIC-E

circuitry during programming. JP4 must be installed

(closed) during normal PIC-E operation.

4PJ

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gnimmargorPnepO

5PJ

evieceR416XMDXR

hctiwSnoitpO2WS

J3/J4/J5/J6 – Microphone/PTT Programming Header

Jumpers J3/J4/J5/J6 configure your microphone and

radio to the PIC-E. A microphone connects to Jack J1

(RJ-45) and a radio to J2 (RJ-45). Refer to the Radio

and Microphone Interfacing section to configure these

headers.

slangiSE-CIPslangiSkcaJenohporciM

9)*(dnuorG8

01V5+7

11dnuorGCIM6

21)*(oiduACIM5

31AXR4

41)*(TTPCIM3

51dnuorGoidaR2

61rewoPCIM1

J5 J6 J4

TAPR PIC-E Manual May 1999 Page 15 of 16

TROUBLESHOOTING

Most problems stem from bad solder connections.

Inspect all solder connections. Make certain that there

are no solder bridges or cold solder joints with a dull

gray appearance. All solder joints should be smooth

and shiny.

Check parts placement paying particular attention to

components that are polarity sensitive such as the

voltage regulator U2, transistor Q1, LEDs, and diodes.

Check that ICs U1 and U3 are inserted with the notch

on the chip matching the notch on the socket.

Power Problems - If the PIC-E is not operating

correctly, check that the output of the 78L05 voltage

regulator U2 is outputting +5 volts. You can measure

this on pin 1 of JP4. Check that +5 volts are available

on U1 pin 14 of the PIC and U3 pin 16 the MX614

chip. Trace the voltage signal using the schematic.

Page 16 of 16 May 1999 TAPR PIC-E Manual

Ftp://ftp.tapr.org/picsig/docs/pic E_assy_manual Pic E Assy Manual

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