Countermeasure: Turn on the ADC Power of GPIO39.

#include <driver/adc.h>
void setup(){
adc_power_acquire(); // ADC Power ON

The countermeasures have been clarified by the investigation and analysis of Mr. nao *.
https://twitter.com/mikasa231/status/1403576681701335044
We would like to thank Mr. nao * for his efforts.

ded it to my blog. Postscript: 2021.06.13
ButtonA on M5Stack does not work properly
https://macsbug.wordpress.com/2021/05/02/buttona-on-m5stack-does-not-work-properly/

@aattila

Very great!

arduino-esp32 version 1.0.5-rcX
The compiled project will not work consistently because there is a wifi related bug and sometimes the button A (left) will receive the pushed event (many events)

This problem should be cured after wifi.setSleep (False) after wifi.begin.
Please refer to the following.
https://macsbug.wordpress.com/2021/05/02/buttona-on-m5stack-does-not-work-properly/

This is a report of measures for the A button of M5Stack and the B button of M5Stick C to operate without permission.
Workaround：WiFi.setSleep(false);

ButtonA on M5Stack does not work properly : May 02, 2021
https://macsbug.wordpress.com/2021/05/02/buttona-on-m5stack-does-not-work-properly/

I made 4 types of Web Radio with M5Stack.
1.　VS1053B Module
2.　UDA1334A I2S DAC Module
3.　PCM5102A I2S DAC Module
4.　MAX98357A I2S DAC Amplifier Module

Constitution :
1.　Development environment : Arduino IDE 1.8.13
2.　HARD：M5Stack Basic, Gray , Fire
Specification :
1.　Station : 150
2.　Operation : button A：Volume – . button B：Channel up . button C：Volume +
//------------------------------------------------------------------------------------

1.　Web Radio of M5Stack : Jan 08, 2021
https://macsbug.wordpress.com/2021/01/08/web-radio-of-m5stack/
Constitution :
1.　Library：baldram/ESP_VS1053_Library
2.　HARD：VS1053B Board
Cost : $11


//------------------------------------------------------------------------------------

2.　Web_Radio_of_M5Stack_I2S_DAC : Feb 14, 2021
https://macsbug.wordpress.com/2021/02/14/web_radio_of_m5stack_i2s_dac/
Constitution :
_1. HARD：UDA1334A I2S DAC Module
Specification :
_1. Document vocalization function
Cost : $10

//------------------------------------------------------------------------------------

3.　Web Radio of M5Stack PCM5102A I2S DAC : Feb 19, 2021
https://macsbug.wordpress.com/2021/02/19/web-radio-of-m5stack-pcm5102a-i2s-dac/
Constitution :
_1. HARD：PCM5102A I2S DAC Module
Specification :
_1. Document vocalization function
Cost : $10

//------------------------------------------------------------------------------------

4.　Web Radio with a built-in speaker in M5Stack : Apr 16, 2021
https://macsbug.wordpress.com/2021/04/16/web-radio-with-a-built-in-speaker-in-m5stack/
Constitution :
_1. Library：schreibfaul1/ESP32-audioI2S
_2. HARD：MAX98357A I2S DAC Amplifier Module
_3. HARD：50x50mm Speaker
_4. HARD：2400mA Battery Module
Specification :
_1. Document vocalization function
Cost : $10


//------------------------------------------------------------------------------------

What is EasyLoader?
SD-UPdater for M5StickC is below.

matsumo / M5StickC-SD-Updater
https://github.com/matsumo/M5StickC-SD-Updater

I had also a closer look at the PCB and recognized a "missing" component near the RESET button:

The part is C44 100nF.
Removed on M5Stack Fire to prevent Nois.

See below.
Parts arrangement of M5Stack
https://macsbug.wordpress.com/2020/04/01/parts-arrangement-of-m5stack/

8. GPIO23 Radiation, Audio Amp
   Audio Amp：
   _ 2. C44 to U9-4: BASIC and GRAY are connected. FIRE is not connected.
   FIRE: Noise is reduced by removing C44 from U9-4.

The MAX40200 is a great idea.

1. I want a power switch for M5Stack 700mA BATTERY MODULE.
2. I have switched on the Battery side.
   Example 1: AA, AAA battery adapter for M5Stack.
   https://macsbug.wordpress.com/2019/04/30/aa-aaa-battery-adapter-for-m5stack/
   Example 2: M5STACK Strongest 2400 mAh Battery Module
   https://macsbug.wordpress.com/2018/08/20/m5stack-strongest-2400-mah-battery-module/
   Example 3: Low price Battery Module of M5STACK
   https://macsbug.wordpress.com/2018/06/23/low-price-battery-module-of-m5stack/

The following information may be helpful.

1. Cannot write to M5StickC on macOS Catalina :
   https://qiita.com/SamAkada/items/fa32d6072a832a10cd84

2. How to solve the problem that M5StickC can not be written with Arduino IDE of macOS Catalina :
   https://tech.fusic.co.jp/posts/2020-02-12-macos-catalina-m5stickc/

There is a way to attach a diode to the Battery Module.
Blog：USB Cable and Reset prevention
https://macsbug.wordpress.com/2020/04/07/usb-cable-and-reset-prevention/