The baudrate of 230400 doesn't work

Question

Hi,

Since I need to transfer data between Jevois and my drone by high frequency, I need to increase the baud rate to 230400. However, it seems this baud rate does not work. According to the documentation, some baud rate does not work. My question is whether there is any report that 230400 works or not?

I found there is another question about this kind of baud rate problem. Is it solved?

Regards

Answer 1

Can your micro-controller handle 1.5 Mbps? Looking around for "allwinner a33 baudrate" I found this:

https://forum.armbian.com/topic/3508-higher-uart-baud-rates-h3/

Even though this is a different chip, looks like maybe we have the same issue here.

I tried 1.5 Mbps and it works, at least using a USB to serial dongle connected to the 4-pin serial port of jevois. 

Proceed as follows:

- Insert MicroSD into computer (what we will do is not supported by JeVois inventor, which is intended for more novice users)

- edit JEVOIS:/jevois/config/params.cfg

- uncomment the line that sets serialdev and the one that sets baudrate, then change baudrate to value 1500000. Note: you must have the line that sets serialdev first. This will trigger instantiation of the serial driver, which otherwise would be delayed until later during boot, when the baudrate cannot be set anymore.

- properly eject microSD and put it into jevois

- attach USB-to-Serial to jevois and launch a terminal for it, setting to 1.5Mbps; for example, on a linux host:

sudo screen /dev/ttyUSB0 1500000

- connect mini-USB cable to JeVois

- bingo, you should see a message

INF READY JEVOIS 1.12.0

in your screen terminal, and you can send commands like info, help, etc

We will test which speeds work and update the docs shortly.

Comments

So with a 24MHz base clock it looks like only these work: 9600, 115200, and 1500000. In principle 380400 should work too, but now that rate is undefined in the standard rate definitions from termios.h ...

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Thanks for your detailed information. I will test this baud rate on my drone :)