Serial command line access on UART1 or UART2?

Steve Veerman

Hello,

I am using an Omega2S+, and while I can successfully connect to UART0 for a serial command line (using a CP210x USB to UART), I have had no luck for UART1 and UART2. Is this even possible? If so, how would I enable it?

The Omega2S Datasheet indicates that:

There are three (3) 2-pin Serial UARTs available. The UART logic level is 3.3V.
The default bootloader and operating system use UART0 to provide serial command line access.

For reference, here are the pin assignments for the Omega2S+ that I am using:

No	Name	Description
39	GPIO_12 / UART_TXD0	Serial UART0 Lite TXD
40	GPIO_13 / UART_RXD0	Serial UART0 Lite RXD
20	GPIO_45 / UART_TXD1	UART1 Lite TXD
21	GPIO_46 / UART_RXD1	UART1 Lite RXD
51	GPIO_20 / PWM_CH2 / UART_TXD2	UART2 Lite TXD
52	GPIO_21 / PWM_CH3 / UART_RXD2	UART2 Lite RXD

György Farkas

@Steve-Veerman I think your table is correct. You could test also UART1 and UART2 with a CP210x and running some serial communication program (eg. picocom, screen, minicom etc.) on your Omega2S+ (or simply with the usual echo - cat commands).
9600 8 N 1 is the default setting on these serial ports - see below.

Unfortunately I don't have any Omega2S(+) module - so I've tried the serial ports only on Omega2(+).

UART0 - TX0 GPIO12 - RX0 GPIO13 - default setting 115200 8 N 1 - Serial Console
UART1 - TX1 GPIO45 - RX1 GPIO46 - default setting 9600 8 N 1

As you know GPIO20 and 21 are exposed only on the Omega2S(+) (ie. on the SMT versions) but after this command
omega2-ctrl gpiomux set spi_s pwm01_uart2
we could use UART2 (ttyS2) on Omega2(+) as well.
UART2 - TX2 GPIO16 - RX2 GPIO17 - default setting 9600 8 N 1

See also my previous posts: enable uart2 is posiible on Omega2+??

Steve Veerman

@György-Farkas thanks for the reply.

I have two CP210x devices, one connected to UART0 (115200 8 N 1) and another to UART1 (9600 8 N 1).

I then have two instances of PuTTY running, one connected to UART0 and another to UART1.

The UART0 screen has a command prompt, and I can successfully issue commands, but UART1 screen has no such prompt.

I can successfully issue this command on UART0 to UART1:

echo "test" > /dev/ttyS1

On the UART1 screen, I see:

test

Also, I notice when I type anything into the UART1 screen, I immediately see it echoed verbatim on the UART0 screen. UART1 doesn't seem to be able to issue/run commands. I'm interested in using command prompt on the UART1 to be able to issue commands. Is this possible?

György Farkas

@Steve-Veerman If I know well - Linux is able to use only one Serial Console - due to some kernel limitation.

Steve Veerman

@György-Farkas damn, I was hoping this wasn't the case. Thanks for your help though.