CODEWITHSUNDEEP
pythonpicpyserialftdi
generic purple turtle
generic purple turtle

Reputation: 471

PySerial - Max baud rate for platform (windows)

I'm trying to get pySerial to communicate with a microcontroller over an FTDI lead at a baud rate of 500,000. I know my microcontroller and FTDI lead can both handle it as can my laptop itself, as I can send to a putty terminal at that baud no problem. However I don't get anything when I try to send stuff to my python script with pySerial, although the same python code works with a lower baud rate.

The pySerial documentation says:

"The parameter baudrate can be one of the standard values: 50, 75, 110, 134, 150, 200, 300, 600, 1200, 1800, 2400, 4800, 9600, 19200, 38400, 57600, 115200. These are well supported on all platforms.

Standard values above 115200, such as: 230400, 460800, 500000, 576000, 921600, 1000000, 1152000, 1500000, 2000000, 2500000, 3000000, 3500000, 4000000 also work on many platforms and devices."

So, I'm assuming why it's not working is because my system doesn't support it, but how do I check what values my system supports/is there anything I can do to make it work? I unfortunately do need to transmit at least 250,000 and at a nice round number like 250,000 or 500000 (to do with clock error on the microcontroller).

Thanks in advance for your help!

Upvotes: 4

Views: 5533

Answers (1)

generic purple turtle
generic purple turtle

Reputation: 471

So I found that the rounded numbers didn't work i.e. 100000, 200000, 250000 but the multiples of 115200 do. i.e. 230400, 460800

I tried to use 230400 at first but the baud rate my microcontroller can produce is either 235294 or 222222. 235294 yields an error of -2.1% and 222222 yields an error of 3.55%. I naturally picked the one with the lower error however it didn't work and didn't bother trying 222222. For some reason 222222 works when 235294 though. So I don't actually have to use the 250000 baud rate I initially thought I'd have to.

I still don't know why pyserial doesn't work with those baud rates when putty does, so clearly my laptop can physically do it. Anyway will know in future to try more standard baud rates as well as when using microcontrollers which can't produce the exact baud rate required to try frequencies both above and below.

Upvotes: 2

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