fix: Wireless Paper (v1.0 & v1.1) not showing battery percentage

[todd-herbert]

Addresses #3131

Affects:

Boards which are both:

• ESP32S3, and
• Measure battery with ADC2

As far as I am aware, this is currently only Wireless Paper V1.0 and V1.1.
Presumably any new boards meeting the criteria will suffer from the same issue?

Caveats:

usbPower and isCharging are not working correctly.
Looking at the schematic, it might not be possible to get the necessary information (?)

• With no battery connected, VBAT hovers around 3.9V
• The C̅H̅R̅G̅ pin of the TP4054 Li-lon Battery Charger IC does not connect to the MCU, only to an orange LED.

Code changes:

• ADC config in variant.h (both boards)

• Use gate ADC_CTRL to connect / disconnect voltage divider

• For ESP32S3: avoid "ADC2 wifi bug workaround". Not required for S3, and breaks compile:

  firmware/src/Power.cpp

  Lines 271 to 273 in 1d44815

  	// ADC2 wifi bug workaround, see
  	// https://github.com/espressif/arduino-esp32/issues/102
  	WRITE_PERI_REG(SENS_SAR_READ_CTRL2_REG, RTC_reg_b);

  
  Instead, check the esp_err_t returned by adc2_get_raw() to confirm that read was successful.

• For ESP32S3: handle new enum value in logging:

  firmware/src/Power.cpp

  Lines 428 to 433 in 1d44815

  	#ifdef CONFIG_IDF_TARGET_ESP32S3
  	// ESP32S3
  	else if (val_type == ESP_ADC_CAL_VAL_EFUSE_TP_FIT) {
  	LOG_INFO("ADCmod: ADC Characterization based on Two Point values and fitting curve coefficients stored in eFuse\n");
  	}
  	#endif

[todd-herbert]

@code8buster I do realize the suggestion was that the deprecated interface should be avoided. #3131 (comment)

I did look into the new API, but as far as I could tell (and I'm no expert), the required methods haven't yet been implemented in the Heltec Enviornment, despite recent releases.

[Gabrielerusso]

Caveats:
usbPower and isCharging are not working correctly.
Looking at the schematic, it might not be possible to get the necessary information (?)
With no battery connected, VBAT hovers around 3.9V
The C̅H̅R̅G̅ pin of the TP4054 Li-lon Battery Charger IC does not connect to the MCU, only to an orange LED.

same as Heltec Tracker schematic, charge voltage is around 4.15V (average), isCharging in my case is working only with full battery as the lookup table i use measures anything above 4150mV as fully charged, so by going over that it recognizes it's connected.

For the usbPower also there is the same problem.

I don't understand why the charge output of the TP4057 isn't connected even if would be pretty simple to do so afterwards (DIY).

[todd-herbert]

@Gabrielerusso Sorry, that was an accident; I bumped the button. I know you've already reviewed it. Thanks for your input.

[code8buster]

I don't really have hardware to test this with, but it does pass the smell test.
It's possible that your code for reading adc2 is actually better overall.

I never found anyone to test the "workaround" with a heltec v2/2.1 that was also connected to wifi.

[todd-herbert]

It might have been unnecessary at this point, but here is at least some measure of proof.