µBITX Updates

I've had the µBITX on the air for about two weeks straight running WSPR on 20m during the day and 40m over the night.  I have been successful in hearing and reaching around the world with 5 watts.

Sound card and CAT control with a single USB connection

From previously posted pictures, one can see that my cabling is a bit of a rat's nest.  My sound card was a $5 external unit while the CAT control was a separate connection.  I was going to crack open the case of the cheapie sound card to make direct audio connections and use a small hub to have a single USB connection to the PC.  But I stumbled onto a YouTube video from ELEKITSORPARTS that showed a sound card with integrated USB hub to allow CAT control using a single connection to the host computer.  The thing that sold me on it is that it isolates the radio from the computer which is something I would not have been able to accomplish with my hack job.

So I ordered one.  It took a few weeks to get here.  This weekend I wired it up and it seems to be working well with the Raduino.  But I want to replace the Raduino...

The Arduino nano is a fine choice to control a basic radio.  It has plenty of program space, it runs at a decent speed, and it has a bunch of GPIO.  But the RAM is a bit small and it only has a single serial port that is used by for CAT control via USB.  I was looking for options to be able to have multiple serial ports for interfacing various peripherals.

After researching various options, I decided to use the Teensy LC.  It has more of everything in a really small package but it isn't overboard (a Teensy 4 would be fun, but it's a bit much).  It has great support and is almost a drop in replacement for the nano.  I was able to connect the LCD with the same digital pins and wire the Si5351 via I2C.  And I am able to easily compile the µBITX code thanks to the Teensyduino add-on for the Arduino IDE. 

The first attempt at wiring the Teensy to the µBITX

I have used the Si5351 from Adafruit to generate an IF for the SSB6.1 single board radio with good results.  The µBITX uses all three clock outputs to generate the IF and BFO.  I hacked the connections via 10 cm jumpers from a breadboard which isn't ideal but it works for testing.

The only problem I had was what I thought was a failure with communicating with the LCD.  I did not understand the warning that the Teensy bootloader was giving me regarding it dropping out of automatic mode.  The LCD backlight is wired to the USB 5 volt line and without a resistor inline, it caused the Teensy to stop running because it sucked all of the current.  Once I added the resistor, everything ran fine.

Since I did not connect the VFO encoder, the Teensy LC controls the radio via CAT commands.  WSPR-X is able to set the frequency and decode messages...

Teensy LC and Si5351 with the µBITX copying FT-8