This project evolves from an already existing hardware built by CT1BMU and his son, based on what is supposed to be an original by a Brazilian fellow ham but no references to he original author were found.
The need to change what was already done comes from the feature that we have already integrated in a couple of repeaters - inhibit the voice announcement ID while the repeater is being used.
There was a problem though, no information existed regarding software and hardware.
Meanwhile, after some time, Emanuel CT1BDV was able to supply what was the original schematic without the post modifications/adaptations made by CT1BMU.
With the schematic and controller in our hands we were able to map those modifications and have a base schematic to work on for the software/firmware which was lacking.
The controller connects two radios (2x Motorola GM350) and needs to provide all the basic functionalities:
- Repeat signals present at the receiving end
- Implement TOT (Time out Timer)
- Implement the repeater ID with inhibition while in use
- Reuse the morse/beeping circuitry
The software was written from scratch in bare metal C code for the ATMEGA328P. It uses all the three timers and a few IO pins:
| Pin | Ref | I/O | Description |
|---|---|---|---|
| 2 | PD0 | Out | TX PTT control |
| 3 | PD1 | Out | RX Audio mute/unmute control |
| 4 | PD2 | Out | RX Led |
| 5 | PD3 | Out | TX Led |
| 6 | PD4 | Out | TOT Led |
| 11 | PD5 | Out | External ISD board play control |
| 19 | PB5 | In | Receiver COS/COR/CAS signal |
| 23 | PC0 | Out | Morse/Beep digital output |
The LED indicating POWER ON is not on the schematic above. A power cable from the led directly into the 13.8V DC Input with a resistor in serie was used.
NOTES:
- AVcc should be connected to VCC. (ADCs not used)
- All unused IOs are configured as OUTPUTS and tied to LOW level
- Two 1N4148 diodes were added in series from +5V to the VCC on the ISD board
- to reduce voltage down to less than 4 volts and avoid stressing the circuit.
AUTO ON (OUT 2 <-> IN 6 - IGNITION)
MIC /`````\
| / \
2 4 6 8 10 12 14 16
1 3 5 7 9 11 13 15
| |
PTT GND
The RX radio has a hack, not sure the reason why but the COR/CAS signal is not exposed on the back connector and a cable was soldered inside the radio via a green cable.
RED CABLE GOES TO GREEN WIRE (COMES FROM THE RADIO)
THERE IS AT LEAST ONE RESISTOR CONNECTING BOTH WIRES
I SUSPECT IT IS THE COR/COS SIGNAL
2 4 6 8 10 12 14 16
1 3 5 7 9 11 13 15
| |
GND RX_AUDIO (FLAT)
The C code has comments that better explain the implementation and most parameters are exposed as definitions that can be edited and then recompiled.
The new firmware implements the following:
- TOT Time out timer (3 min.)
- on TOT enter, beep burst with rx audio mute
- TOT penalty of 1.5 sec. No RX can happen, in the mentioned time, to disable TOT
- while in time out, transmit "TOT" in Morse, every 5 sec.
- on TOT leave, transmit "K" in morse
- Voice ID every 10 minutes (ISD)
- when reaching ID time, the last 6 sec must be without any rx (ID wait)
- every hour, after the voice ID, the callsign is also sent in morse
- 1 second tail with 1.25 kHz 40 ms beep indicating TOT timer reset. A morse T
- On ID wait, evaluating the last 6 seconds before ID, the tail will resemble a morse I
Below in this document, there's a couple tips on how to setup the toolchain.
To build the firmware you can use make. To flash use make flash followed by
make fuse to "burn the fuses".
We've used the programmer XGecu TL866 II Plus (TL866II+) with minipro linux software.
As always, thanks to the ARM team in particular, by callsign order:
- CT1BDV Emanuel
- CT1EUK Freitas
- CT1EYN Costa
- CS7AFE Carlos
- CS7ALF Constantino
- CR7AQJ Soares
and to the testers:
- CT1ENP Ribeiro
- CT1EUK Freitas
- CT1EYN Costa
>$ sudo apt-get install gcc-avr binutils-avr avr-libc
>$ sudo apt-get install avrdude
and avr-gcc
Install package 'avr-gcc' to provide command 'avr-gcc'? [N/y] y
* Waiting in queue...
The following packages have to be installed:
avr-gcc-1:11.2.0-1.fc36.x86_64 Cross Compiling GNU GCC targeted at avr
Proceed with changes? [N/y] y
$ avr-gcc -Os -DF_CPU=16000000UL -mmcu=atmega328p -c -o blink_led.o blink_led.c
We create the executable:
$ avr-gcc -mmcu=atmega328p blink_led.o -o blink_led
And we convert the executable to a binary file:
$ avr-objcopy -O ihex -R .eeprom blink_led blink_led.hex
Finally, we can upload the binary file:
$ avrdude -F -V -c arduino -p ATMEGA328P -P /dev/ttyACM0 -b 115200 -U flash:w:blink_led.hex
Look at your Arduino Uno! The led is blinking!
After upgrading to Fedora 37 the infoic.xml error appeared. Workaround is to copy the file to the location of project where you run minipro to flash. That's why you see the file in this folder, with the code. Don't need to include in git. In Fedora 37, it's residing originally in /usr/share/minipro/