How to communicate throught UART?

nicolas_sunbirds · January 18, 2021, 4:22pm

Hi,

I want to implement a custom process in order to allow the pixhawk (cube black) to a custom device.
I need to read/write on a serial port. I do not use GPS2 port, thus I chose this one to communicate.
Here is the very simple code (that does not work) :

AP_HAL::UARTDriver* uart;
uart = hal.uartE;
if(uart == nullptr){
return;
}
uart->begin(9600);
uart->configure_parity(0);
uart->set_stop_bits(1);

The thing is, it does not work as the autopilot does not boot. After flashing the firmware, i cannot connect to the autopilot, as there is no usb port to connect to.

If I’m replacing hal.uartE by hal.uartH, it works properly ( ls -l /dev/tty* shows me a /dev/ttyACM0, and I can connect to my autopilot with MissionPlanner).

Why doesn’t it work with uartE ? How should I do to use GPS2 port ?

I’m using latest firmware, latest MissionPlanner, and Cube Black as an autopilot

Mustafa_Gokce · January 18, 2021, 4:56pm

If you are not familiar with the ardupilot code base, I recommend you to work on lua scripting.

github.com

ArduPilot/ardupilot/blob/master/libraries/AP_Scripting/examples/serial_test.lua

-- Lua script to write and read from a serial

local port = serial:find_serial(0)

port:begin(115200)
port:set_flow_control(0)

local step = 65

function spit ()
  if port:available() > 0 then
    read = port:read()
    gcs:send_text(0, read .. " = " .. step)
  end
  if step > 122 then
    step = 65
  else
    step = step + 1
  end
  port:write(step)

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I don’t know whether this is suitable or not for your case since I don’t know what your are trying to do but I just wanted to share this feature =)