Docs for gpsd state that it autodetects baud rate of the gps module, but on my system it does not.

On my Pi4B with Adafruit Ultimate Breakout wired to UART5, gpsd can only connect to the GPS at 9600. Matching port speed (using stty) and GPS speed (using gpsinit) works up to 115,200, but only until power cycle, when the GPS retains the new speed but /dev/ttyAMA1 goes back to default. And thus gpsd.service cannot operate at any baud rate but 9600.

Any hints why the gpsd auto baud isn’t functional, and any workaround to use a faster baud rate? Is there a config file or cmdline option to make UART5 115,200 at power up?

  • 1
    check your /boot/cmdline.txt for clues Aug 13, 2020 at 23:21

1 Answer 1


Edit the file /boot/config.txt to add the following line:


  • 1
    I'll check it out, thanks for the quick reply.
    – MAXdB
    Aug 16, 2020 at 3:15
  • Well, I remember sometime ago another SIM800/900 guy asked why his module does not do auto bauding. So I read the manual which indeed says can do autobauding. So I suggested him how to verify, starting from standard default 9600n81 and then step by step to finally prove that his module does not do autobauding even though specified otherwise. I remember the guy asking the question indeed already verified the thing himself, and I only helped verifying that his verification is (almost) perfect. This reminds me how Ronald Reagan read the manuals from Russia, Trust, but Verify..
    – tlfong01
    Aug 17, 2020 at 1:35

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