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Faster UART

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Post time 2016-7-8 00:41:15 | Show all posts |Read mode
Using wiringPi, the fastest UART configurable in serialOpen is 230,400 baud.
I would like to try faster speeds and nonstandard baud rates.
While researching the issue for the ubiquitous RPi, the solution was to increase a variable called init_uart_clock that was found in /etc/config.txt or boot/config.txt
I cannot find either of these files in my Armbian Jessie OPi PC system.
Has anyone tried altering the baudrates to higher, or nonstandard values? I would like a solution that my program can set, then unset when it terminates.
Thanks,

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Post time 2016-7-8 19:35:33 | Show all posts
guess that should be done in .fex

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 Author| Post time 2016-7-8 21:52:30 | Show all posts
I can't find that variable, or anything else that looks appropriate.
I'm more concerned with being able to use non-standard baudrates... but it looks impossible.

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Post time 2016-7-17 01:09:00 | Show all posts
Edited by jernej at 2016-7-16 18:31

Using RPi solutions on OPi is pointless as they have completely different HW and SW. UART speed is usually set in program you are using. For example, if you want to open serial terminal, you might use following command:
  1. screen /dev/ttyS1 115200
Copy the Code

You can select different baud rate, but it must follow the following rule:
(24000000 / 16) / baudrate must be whole number between 1 and 65535. This means that the baud rate 115200 is in reallity 115384, but that is ok as difference is less than 2%.

This also means that the highest speed is 1500000, which I'm using it for BT module on BPI M2+. But this is only for Allwinner's kernel. Mainline kernel handles UART clock differently and probably higher or in-between speeds can also be reached.

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