How to activate UART on ALL-H3-CC

Hardware
1

I have the ALL-H3-CC board. I need to enable UART (serial port). Using raspi-config I enable Serial Port, reboot. But no serial port appears in /dev/.

Also tried this solution but no luck: Enabling and using UART
As with this user, when issuing ldto list command, there are no serial ports in the list.

Any pointers appreciated.

2

UART debug console is enabled by default on ALL-H3-CC. See Libre Computer Board Serial UART Connection and Setup Guide

GPIO maps can be found here for additional UART pins: GPIO Pin Header Maps and Wiring Tool for Libre Computer Boards

Which pins do you UART on?

3

I am trying to communicate with a RPi hat using UART (serial port) at 9600 baud. The pins are 8 (RX) and 10 (TX) on the 40-pin header. On the RPi, this port is referred to as /dev/ttyAMA0. This device does not exist on the Libre.

Also, I need to communicate with this same hat over SPI using pins 19 (MOSI), 20 (MISO), 23 (CLK), 24 (CS). On RPi, this port is referenced as /dev/spidev0.0, whereas this does not exist on the Libre.

Thank you

4

Bumping this question as the UART debug console is not what I am after. I need to enable UART (Serial) on GPIO pins 8 and 9 the same as the RPi, which is usually accessible as /dev/ttyAMA0. The app uses these pins to communicate with an attached hat.

Issuing ldto list there is no UART device available to enable. Here is the output of ldto list:

#Overlays available
i2c0-twi0
i2c1-twi1
i2c2-camera
pwm-disable-uart
spdif
spi0-cs1
spi0-cs1-ili9486-xpt2046
spi0-cs1-spidev
spi0
spi0-spidev
spi1-cs1
spi1-spidev

System has been updated via sudo apt update and then sudo apt upgrade then reboot.

I was able to enable /dev/spidev0.0 by issuing the following
ldto enable spi0-spidev spi0 spi0-cs1
Not sure if spi0-cs1 is necessary or not. Is this the Chip Select pin?

Thank you for any assistance.

5

I am following up on this topic because it appears that I need to create a device overlay for the UART pins in order to enable them. Currently the ALL-H3-CC-* models don’t provide a pre-built UART overlay (see this) but the AML-905x has a pre-built overlay for UART (see here). Since the internal mapping is different, I can’t duplicate the AML dts file and compile it (tried this, no new entries appear in /dev, and when doing ldto disable it crashes the kernel (null pointer).

If anyone could help in writing the dtc file for the ALL-H3 chip to support UART1 (pins 8 and 10) that would be immensely helpful!

6

uart1 and uart1-rts-cts has been added to the wiring tool.