Raspberry Pi 4 PTT Issues

Discussion in 'General Technical Questions and Answers' started by KJ4PVX, Aug 7, 2020.

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  1. KJ4PVX

    KJ4PVX XML Subscriber QRZ Page

    I'm puttying together a GO Kit with a Raspberry Pi as the primary computer for using FLDIGI. However, I've found that when I utilize PTT it temporarily shuts off the serial connection. The computer then detects it again and renames the device. So for example, the device is named /dev/ttyUSB0. I attempt to use PTT through FLDIGI, it activates the ICOM 718 for about 1 second, then drops back into receive. I then check the serial cable name in the /dev directory of the pi and /dev/ttyUSB0 is gone but has been replaced by /dev/ttyUSB1. Obviously, this ain't right. Any ideas?
     
  2. K3RLD

    K3RLD Ham Member QRZ Page

    I don't know how to fix the primary problem (the disconnections), but you can "hardcode" a name to the device so that it doesn't get a different name every time it connects. For example, I've hardcoded my transceivers as /dev/D710G and /dev/706MKIIG (note that if you list usb devices, it will still show them as "/ttyUSBx", but as long as the software (FLDIGI) in this case uses the hardcoded name it will still work).

    I can't remember the process to do this, however - so you'll have to google it.
     
  3. KJ4PVX

    KJ4PVX XML Subscriber QRZ Page

    Thanks...I’m tracking I can do that, I think it will still result in an interruption tough, causing it to drop back to receive mode. My thought is that it’s losing power or getting power on the usb ports.
     
  4. KA9JLM

    KA9JLM Ham Member QRZ Page

    My guess is that it may be over heating.

    What type of cooling system are you using ? Are you using a 4 amp + PS ?

    You should be able to turn off power for the USB ports so that it does not power connected devices that do not need power.
     
    Last edited: Aug 8, 2020
  5. KJ4PVX

    KJ4PVX XML Subscriber QRZ Page

    Well, I’ve got a case with a built in fan. And I’ve tried using a powered usb hub to make sure it wasn’t pulling from the pi. It made no difference.
     
  6. KA9JLM

    KA9JLM Ham Member QRZ Page

    OK. Is there any chance that RF could be getting back into the RPi when the radio goes into transmit ?
     
  7. KJ4PVX

    KJ4PVX XML Subscriber QRZ Page

    Maybe I guess? I think it’s pi specific. I went back and forth between my Linux laptop with the same Flrig/Fldigi settings. No issues with the laptop, the issue still as described with the pi.
     
  8. KA9JLM

    KA9JLM Ham Member QRZ Page

    You may want to test using a dummy load, Or turn your radio power down to Zero and still see if it happens.

    Is your RPi case Metal or Plastic ?

    Good Luck.
     
  9. KJ4PVX

    KJ4PVX XML Subscriber QRZ Page

    Plastic Case. Thanks for the help guys. Walked away from it for a week. Now it works. HAM RADIO!!!
     

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