@felmue
Then I need to change design... thank you so much for answer.

I want to use GPIO16 on M5stack basic v2.6 as digital input but it doesn't work.
I have tried on the code below but it always return 1.
・It's work well on M5 stack gray (default 0, when input 3.3V it return 1).
・In case I use GPIO17,25,26, it can also work well.
・I have 2 of basic v2.6 but both of them have same issue.

This is the code I have tested.

#include "Wire.h"
#include <M5Stack.h>

#define DIN 16
void setup() {
  //start serial connection
  M5.begin();
  M5.Power.begin();
  Wire.begin();
  Serial.begin(9600);
  pinMode(DIN, INPUT_PULLDOWN);
}

void loop() {
  int sensorVal = digitalRead(DIN);
  Serial.println(sensorVal);
}

Do you have any solution or find issue on my code?
Thank you in advance for your help.