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- HOWTO Use analogRead() with ESP32 running WiFi and/or BlueTooth (BT/BLE)
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Khoi Hoang
2020-10-21 14:40:59 -04:00
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@ -157,11 +157,11 @@ This file must be copied into the directory:
- `~/.arduino15/packages/arduino/hardware/sam/x.yy.zz/platform.txt`
4. ***To be able to compile without error and automatically detect and display BOARD_NAME on Arduino SAMD (Nano-33-IoT, etc) boards***, you have to copy the whole [Arduino SAMD cores 1.8.8](Packages_Patches/arduino/hardware/samd/1.8.8) directory into Arduino SAMD directory (~/.arduino15/packages/arduino/hardware/samd/1.8.8).
4. ***To be able to compile without error and automatically detect and display BOARD_NAME on Arduino SAMD (Nano-33-IoT, etc) boards***, you have to copy the whole [Arduino SAMD cores 1.8.9](Packages_Patches/arduino/hardware/samd/1.8.9) directory into Arduino SAMD directory (~/.arduino15/packages/arduino/hardware/samd/1.8.9).
Supposing the Arduino SAMD version is 1.8.8. These files must be copied into the directory:
- `~/.arduino15/packages/arduino/hardware/samd/1.8.8/platform.txt`
- ***`~/.arduino15/packages/arduino/hardware/samd/1.8.8/cores/arduino/Arduino.h`***
Supposing the Arduino SAMD version is 1.8.9. These files must be copied into the directory:
- `~/.arduino15/packages/arduino/hardware/samd/1.8.9/platform.txt`
- ***`~/.arduino15/packages/arduino/hardware/samd/1.8.9/cores/arduino/Arduino.h`***
Whenever a new version is installed, remember to copy these files into the new version directory. For example, new version is x.yy.z
@ -230,6 +230,45 @@ To use the old standard cpp way, just
---
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### HOWTO Use analogRead() with ESP32 running WiFi and/or BlueTooth (BT/BLE)
Please have a look at [**ESP_WiFiManager Issue 39: Not able to read analog port when using the autoconnect example**](https://github.com/khoih-prog/ESP_WiFiManager/issues/39) to have more detailed description and solution of the issue.
#### 1. ESP32 has 2 ADCs, named ADC1 and ADC2
#### 2. ESP32 ADCs functions
- ADC1 controls ADC function for pins **GPIO32-GPIO39**
- ADC2 controls ADC function for pins **GPIO0, 2, 4, 12-15, 25-27**
#### 3.. ESP32 WiFi uses ADC2 for WiFi functions
Look in file [**adc_common.c**](https://github.com/espressif/esp-idf/blob/master/components/driver/adc_common.c#L61)
> In ADC2, there're two locks used for different cases:
> 1. lock shared with app and Wi-Fi:
> ESP32:
> When Wi-Fi using the ADC2, we assume it will never stop, so app checks the lock and returns immediately if failed.
> ESP32S2:
> The controller's control over the ADC is determined by the arbiter. There is no need to control by lock.
>
> 2. lock shared between tasks:
> when several tasks sharing the ADC2, we want to guarantee
> all the requests will be handled.
> Since conversions are short (about 31us), app returns the lock very soon,
> we use a spinlock to stand there waiting to do conversions one by one.
>
> adc2_spinlock should be acquired first, then adc2_wifi_lock or rtc_spinlock.
- In order to use ADC2 for other functions, we have to **acquire complicated firmware locks and very difficult to do**
- So, it's not advisable to use ADC2 with WiFi/BlueTooth (BT/BLE).
- Use ADC1, and pins GPIO32-GPIO39
- If somehow it's a must to use those pins serviced by ADC2 (**GPIO0, 2, 4, 12, 13, 14, 15, 25, 26 and 27**), use the **fix mentioned at the end** of [**ESP_WiFiManager Issue 39: Not able to read analog port when using the autoconnect example**](https://github.com/khoih-prog/ESP_WiFiManager/issues/39) to work with ESP32 WiFi/BlueTooth (BT/BLE).
---
---
### Examples
Also see examples: