How to enable UART A and 921600 Baud Rate for AML-S805X-AC and AML-S905X-CC

Hardware
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1

UART A is on pin 8 and pin 10 with optional flow control on pin 16 and pin 18.

sudo ldto enable uarta
sudo stty -F /dev/ttyAML6 921600

To support the 921600 and other specific baud rate, a different dtoverlay uarta-clk81 must be used in place of uarta.

sudo ldto enable uarta-clk81
sudo stty -F /dev/ttyAML6 921600

There are also other hardware UARTs available and even software UART that can be created on most pins.

  • UART AO B on pin 3 and pin 5.
  • UART C on pin 19 and pin 21 with optional flow control pins 23 and pin 24.

If you need these, please post below.

2

I have this hat, it has 2 x 10 pin headers, the first 10 pins and the last 10 pins, could it be possible it uses UART AO B? I’ve been trying to locate more info in regards to these boards, but still haven’t found anything.

3

We will add and push the overlays for UART AO B in the next 24 to 48 hours.

1 Like
4

We have added UART-AO-B to GitHub - libre-computer-project/libretech-wiring-tool.
You have to manually clone and make for now to enable and merge but it should appear on the apt update in a few days.

5

Thank you. WIll check it out after I tackle my first project.

6

I have done to enable UART A for [AML-S905X-CC]
sudo ldto enable uarta
sudo stty -F /dev/ttyAML6 115200
sudo ldto enable uarta-clk81
sudo stty -F /dev/ttyAML6 115200

then through minicom cmd sudo minicom -b 115200 -o -D /dev/ttyAML6 didn’t get reply on putty terminal.

Following are my question.

  1. How many UART is accessible for [AML-S905X-CC]?
  2. what is procedure to access on board pin on UART? I have done above procedure but nothing get on the putty terminal.
7

You cannot enable uarta and uarta-clk81. They are conflicting as they are both uarta. uarta-clk81 is if you need additional frequencies not available on uarta.

There are 3 per the OP.

8

Hello @librecomputer

how to use UART C on pin 19 and pin 21?

Thank you in advance

9

You just need to create an overlay with uart_C as the target and status = "okay";