PTT CAT control using USB Arduino Nano Every

Mick W8BE

I had developed a CAT control interface utilizing a USB Arduino Nano Every and I had issues with stability. Last week I operated in the VA QSO party and used the PTT SmartCAT interface with my foot switch. It is a Linemaster industrial foot switch and the bounce effect when using the switch was very noticeable. This got me thinking about my CAT control interface. I went back and used Wireshark to examine my FlexControl. I noticed the commands were sent very quickly to the radio. I had the Arduino Nano Every set to 9600 baud. I decided to change the baud and after experimenting I was able to get the device to act in a stable manor. I have updated the repository. I find using the CAT control is very quiet and so far I have had no stability issues Here is the link to the repository.

https://github.com/w8be/usb-ptt-arduino-nano-every/tree/main

KD0RC

Very cool Mick. One trick that I use is to attach an interrupt to the input pin. In the ISR, I immediately disable that interrupt, service the interrupt, and set a timer (20 ms or whatever I need to get past the bouncing). When the timer expires, I enable the interrupt again. This makes sure that I get the earliest possible "make" contact and that additional bounces don't chatter relays and that kind of thing.

For this scheme, I usually attach the interrupt using CHANGE so that I can use the same technique on the break. I often wind up with a different break timeout than make timeout. It mostly depends on the switch and how fast I want to be able to cycle it. PTT will usually have longer time constants than a dot paddle, for example.

Mick W8BE

Thanks Len,

I am including a bounce function from the libraries. I currently have the bounce timer set to 200ms.

Regards

Mick W8BE

Here are a couple pics.

KD0RC

Very clean installation!

Mick W8BE

Ken,

Can you share your ISR code. It may very well be worth switch too.

Thanks

KD0RC

Hi Mick, The full source for my TeensyMaestro is out on GitHub. With everything going on, it will be a challenge to filter out what you need.

Here is a real quick sample:

/*
  Sample Interrupt-driven input
  Len Koppl, KDØRC 
  03/26/24 
  Teensy 4.1(with built - in Ethernet)

*/
// Includes

// Constants
const byte BUTTON_PIN = 0;
const int DEBOUNCE = 20;  // debounce time in ms

// Global Variables
IntervalTimer debounceTimer;

void setup()
{
  attachInterrupt(digitalPinToInterrupt(BUTTON_PIN), buttonISR, FALLING);
}

void loop()
{
  // looping code here
}

// Subroutines

// Interrupt Service Routines
void buttonISR()
{
  detachInterrupt(BUTTON_PIN);  // stop button interrupt to prevent multiple hits (bounce)
  // quick stuff here like setting a variable.  Do not do massive processing in the interrupt service routine.

  debounceTimer.begin(debounceISR, DEBOUNCE);
}

void debounceISR()
{
  debounceTimer.end();
  attachInterrupt(digitalPinToInterrupt(BUTTON_PIN), buttonISR, FALLING); // allow button pushes again after debounce period
}

Hopefully, this helps.

KD0RC

Well, I'm an idiot... That sample code is for a Teensy 4.1, not a Nano Every. If I get a chance, I will see if there is a timer library for the Nano Every. If not, then it might not be worth the effort to do what I am suggesting.

Mick W8BE

Thanks...no rush

Mick W8BE

Update: I have been using my Arduino Nano Every PTT foot switch since March and I am pleased to say it has worked every time I plugged in the usb port and turned the radio on. I have had no issues with rfi and I find the cat command makes no noise compared to the mechanical ptt using a db9 rs232 connector.

Mick W8BE

I have updated the repository for the USB PTT using the Arduino Nano Every to send CAT PTT commands. It is simple to set up and implement.

https://github.com/w8be/usb-ptt-arduino-nano-every

Regards