How to use adc 3.3?

I want to read a adc signal from adc3.3 in pixhawk board how can I do this?

You can check the pinout here, from right to left (the last one is not sure, you should measure it):
5V, PIN14, GND, PIN13, GND

In the code, you need:
AP_HAL::AnalogSource *adc_source; uint8_t pin=14; //or 13 adc_source = hal.analogin->channel(pin); float analog_value = adc_source->voltage_latest();

You can find more functions here, but this is just an abstract class, for the detailed implementations look into the AP_HAL_PX4 library.

I do that and compile the code using make on linux and the compilation process runs succesfully without compile erros. However, when i upload the firmware onto the Pixhawk, the main led initializes, blinks yellow and then stops blinking and when I coment this line “analog_value = adc_source->voltage_latest();” and upload the led blink correctly.

If you could provide a bit more context… what code are you using, and where did you put the stuff?
I usually use the UART_test in the AP_HAL library, because it’s quite minimal, and perfect for debugging.

this my code:

  • float bbb;

  • AP_HAL::AnalogSource *analog_source;

  • #ifdef USERHOOK_INIT

  • void Copter::userhook_init()

  • {

  • // put your initialisation code here
  • // this will be called once at start-up
  • uint8_t pin=14;
  • cliSerial->printf("0");
  • analog_source = hal.analogin->channel(pin);
  • cliSerial->printf("1");
  • }

  • #endif


  • void Copter::userhook_MediumLoop()

  • {

  • // put your 10Hz code here
  • cliSerial->printf("3");
  • bbb=analog_source->voltage_latest();
  • cliSerial->printf(“4”);

  • //hal.scheduler->delay(100);

  • }

  • #endif

in terminal I can’t see any number

i upgrade my linux and the problem solved :slight_smile: