Using GetBatteryVoltage() function causes my adc1 based ULP process to stop working

[mbbender]

tinypico-arduino/TinyPICO-Helper/src/TinyPICO.cpp

Lines 207 to 230 in 3b364e6

	float TinyPICO::GetBatteryVoltage()
	{
	uint32_t raw, mv;
	esp_adc_cal_characteristics_t chars;
	// only check voltage every 1 second
	if ( nextVoltage - millis() > 0 )
	{
	nextVoltage = millis() + 1000;
	// grab latest voltage
	analogRead(BAT_VOLTAGE); // Just to get the ADC setup
	raw = adc1_get_raw(BATT_CHANNEL); // Read of raw ADC value
	// Get ADC calibration values
	esp_adc_cal_characterize(ADC_UNIT_1,ADC_ATTEN_11db ,ADC_WIDTH_BIT_12,DEFAULT_VREF,&chars);
	// Convert to calibrated mv then volts
	mv = esp_adc_cal_raw_to_voltage(raw, &chars) * (LOWER_DIVIDER+UPPER_DIVIDER) / LOWER_DIVIDER;
	lastMeasuredVoltage = (float)mv / 1000.0;
	}
	return ( lastMeasuredVoltage );
	}

I'm not familiar enough yet with how the adc is configured and used and reused, but in debugging my program I've found that if I call the GetBatteryVoltage() function anywhere in my code... the ULP program I have that uses adc1 to wake on hall sensor readings fails to execute. I'm guessing because of the way this function uses the ADC that perhaps there needs to be some kind of release or reset on the adc? The ULP loading code looks like this:

esp_err_t err = ulp_load_binary(0, ulp_main_bin_start,
                                  (ulp_main_bin_end - ulp_main_bin_start) /
                                      sizeof(uint32_t));
ESP_ERROR_CHECK(err);
adc1_config_channel_atten(ADC1_CHANNEL_0, ADC_ATTEN_DB_0);
adc1_config_channel_atten(ADC1_CHANNEL_3, ADC_ATTEN_DB_0);
adc1_config_width(ADC_WIDTH_BIT_12);
adc1_ulp_enable();
esp_err_t ulp_run_err =
    ulp_run((&ulp_entry - RTC_SLOW_MEM) / sizeof(uint32_t));
if (ulp_run_err != ESP_OK)
  log_e("Failed to run ULP program.");