Using ADCCTRL to read an external voltage

[SLevi.1]

Starting with the BLE_Heartrate example, I want to measure a voltage on PA8 of STM32WBA65. The BLE_Heartrate project already has the option of using ADCCTRL to read the internal temperature so as to calibrate the BLE power.

I have added PA8 as ADC_Channel1 in CubeMX. Do I need to call MX_ADC4_Init or not?

How do I achieve a read of PA8 in my timed task? The call to ADCCTRL_RequestRawValue always returns without error, but the value read is always 1 or 2. There is definitely 1.0v on this pin.

My code (copied from the temp_measurement.c of WPAN) is:

static ADCCTRL_Handle_t LLADCRequest_Handle =
{
  .Uid = 0x00,
  .State = ADCCTRL_HANDLE_NOT_REG,
  .InitConf =
  {
    .ConvParams =
    {
      .TriggerFrequencyMode = LL_ADC_TRIGGER_FREQ_LOW,
      .Resolution = LL_ADC_RESOLUTION_12B,
      .DataAlign = LL_ADC_DATA_ALIGN_RIGHT,
      .TriggerStart = LL_ADC_REG_TRIG_SOFTWARE,
      .TriggerEdge = LL_ADC_REG_TRIG_EXT_RISING,
      .ConversionMode = LL_ADC_REG_CONV_SINGLE,
      .DmaTransfer = LL_ADC_REG_DMA_TRANSFER_NONE,
      .Overrun = LL_ADC_REG_OVR_DATA_OVERWRITTEN,
      .SamplingTimeCommon1 = LL_ADC_SAMPLINGTIME_814CYCLES_5,
      .SamplingTimeCommon2 = LL_ADC_SAMPLINGTIME_1CYCLE_5
    },
    .SeqParams =
    {
      .Setup = LL_ADC_REG_SEQ_CONFIGURABLE,
      .Length = LL_ADC_REG_SEQ_SCAN_DISABLE,
      .DiscMode = LL_ADC_REG_SEQ_DISCONT_DISABLE
    },
    .LowPowerParams =
    {
      .AutoPowerOff = DISABLE,
      .AutonomousDPD = LL_ADC_LP_AUTONOMOUS_DPD_DISABLE
    }
  },
  .ChannelConf =
  {
    .Channel = LL_ADC_CHANNEL_0,//LL_ADC_CHANNEL_TEMPSENSOR,
    .Rank = LL_ADC_REG_RANK_2,
    .SamplingTime = LL_ADC_SAMPLINGTIME_COMMON_1
  }
};
	uint16_t battery = 3700;


ADCCTRL_Cmd_Status_t eReturn = ADCCTRL_RegisterHandle (&LLADCRequest_Handle);
		 UTIL_SEQ_PauseTask(1U << CFG_TASK_TEMP_MEAS);
		  /* Enter limited critical section : disable all the interrupts with priority higher than RCC one
		   * Concerns link layer interrupts (high and SW low) or any other high priority user system interrupt
		   */
		  UTILS_ENTER_LIMITED_CRITICAL_SECTION(RCC_INTR_PRIO<<4);

		/* Request ADC IP activation */
		ADCCTRL_Cmd_Status_t ret = ADCCTRL_RequestIpState(&LLADCRequest_Handle, ADC_ON);

		/* Get temperature from ADC dedicated channel */
//				  ADCCTRL_RequestTemperature (&LLADCRequest_Handle,
//				                              &temperature_value);
		ret = ADCCTRL_RequestRawValue (&LLADCRequest_Handle, &battery);

		/* Request ADC IP deactivation */
		ret = ADCCTRL_RequestIpState(&LLADCRequest_Handle, ADC_OFF);

		  /* Exit limited critical section */
		  UTILS_EXIT_LIMITED_CRITICAL_SECTION();

		  // Resume BLE temp task
		  UTIL_SEQ_ResumeTask(1U << CFG_TASK_TEMP_MEAS);