Olimex Support Forum

OLinuXino Android / Linux boards and System On Modules => A20 => Topic started by: gz on April 13, 2023, 08:37:36 AM

Title: multiplexing
Post by: gz on April 13, 2023, 08:37:36 AM
Hi
have an A20-OLinuXino-Lime2 board and try to use uart3
i noticed that uart3 is multiplexed on gpio1 pins 17,19
according to manual i run ~#olinuxino-overlay and set uart3 enable
when reboot i see that it is ok enabled
also ls-l /dev/ttyS3 outputs
but when i test: echo "some string" > /dev/ttyS3 i detect no activity
on osciloscope???
what am i missing step ?
please help
Title: Re: multiplexing
Post by: LubOlimex on April 13, 2023, 08:45:42 AM
uart3 is probably not ttyS3 but other check all ttySx
Title: Re: multiplexing
Post by: gz on April 13, 2023, 08:53:58 AM
you mean? or bigger?
uartX x=1,2
Title: Re: multiplexing
Post by: mactronica on April 13, 2023, 04:55:29 PM
Hello,
uart3 should be mapped to /dev/ttyS1. Make a test on it.

That is defined in overlay dts https://github.com/OLIMEX/olinuxino-overlays/blob/master/sun7i-a20/sun7i-a20-uart3.dts (https://github.com/OLIMEX/olinuxino-overlays/blob/master/sun7i-a20/sun7i-a20-uart3.dts)
Giuseppe.
Title: Re: multiplexing
Post by: Ravor on May 16, 2023, 10:45:50 PM
Quote from: gz on April 13, 2023, 08:53:58 AMyou mean? or bigger?
uartX x=1,2
Are the rest of the uarts on? If not, then uart 3 is ttyS1, since ttyS0 is uart0, and uart1 and uart2 are not included.
Title: Re: multiplexing
Post by: LubOlimex on May 17, 2023, 08:26:06 AM
QuoteAre the rest of the uarts on? If not, then uart 3 is ttyS1, since ttyS0 is uart0, and uart1 and uart2 are not included.

Run olinuxino-overlay to check which are enabled and to enable/disable UARTs. Refer to this document:

https://github.com/OLIMEX/OLINUXINO/blob/master/DOCUMENTS/OLIMAGE/Olimage-guide.pdf
Title: Re: multiplexing
Post by: gz on May 23, 2023, 02:06:35 PM
thank's found ok