2nd CAT - DUO talk

It got very frustrating using the Arduino UNO for the CAT <-> DUO project (below). Mainly due to conflicts between timers and interrupts used by the "SoftwareSerial" library to talk to the DUO USB and interrupts used by the "Rotary" library for the encoder. I wanted to continue to use the Rotary library as I have used it many times and it works well.

 

Rear view of DUO transceiver

Right: CAT USB B interface

So I have switched to an Arduino MEGA, a different beast altogether. The MEGA is longer than the UNO, but has the same basic pinout plus it adds a lot more analog and digital pins, a separate I2C bus and most importantly it has 3 extra serial ports. So the SoftwareSerial library is not needed to talk to the DUO USB.

All that is needed is to start one of the extra serial ports (serial 2, which uses pins 16/TX2 & 17/RX2), is

Serial2.begin(38400);

Which enables the connected USB A host module for a connection to the DUO USB B slave input/output.

Module connected to Serial2 port

BUILD

This is the system

Top, the USB power/programming from my Macbook

on the Left: TR switch

Right: tuning, step and mode

Bottom: display and USB host master to radio CAT USB

Schematic

CODE

Latest code for this CAT_MEGA app is here.

NEXT

I have so far got:

1. Send frequency tuning

2. Send TX/RX command

3. Send mode LSB-USB-CW-FM-AM

4. Change local frequency tuning step (100Hz, 1kHz, 10kHz but could be increased)

I have not managed yet to get data back from the SDR, that is to read values back to the MEGA. Read/Answer does work, but there seems to be timing errors, and to poll the SDR over and over means a huge amount of CAT activity, and maybe either the baud rate (38400 used) is too low or the SDR simply cannot respond quick enough.

However I will try to find out what is going on as one of the targets is to have a "two way" system. So that if you tune or change mode or TX/RX on the radio the MEGA follows along.