RS485 direction and Torizon

fabrizio.camagna · January 5, 2021, 9:49am

I’m porting software from WincE to Torizon on our hardware with colibri, in the past we have used RTS to change direction of half duplex ( RS485) interface with RTS_CONTROL_TOGGLE in WinCE. Now with Torizon your uart driver can do it (toggle RTS to manage direction?) or do you have other solution for it to do quickly, because if we use external GPIO change direction in the application could be very slow in a master/slave protocol like Modbus with the risk to loose received packets after tramission completed during TX to RX driver transition.

saijanani.tx · January 5, 2021, 6:01pm

Hello @fab.camagna ,

Greetings from Toradex!

The solution you mentioned is what we go with but perhapsyou could also check out these links for more information:

https://www.kernel.org/doc/Documentation/serial/serial-rs485.txt

gist.github.com

https://gist.github.com/amarburg/07564916d8d32e20e6ae375c1c83a995

rs485_ioctl_test.c

/*
 * Test program Linux RS485-mode ioctls.
 *
 * cc -o rs485_mode rs485_mode.c
 */

#include <stdlib.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>

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I hope this is useful for you!

Thanks and Regards,
Janani