ESP32 use NVS, but always reset. error "ESP_ERR_NVS_KEY_TOO_LON"

If Word count for NVS KEY >15,ESP32 will  restart ,and you maybe get "ESP_ERR_NVS_KEY_TOO_LON" error in serial monitor.

How fo fix pip install pycrypto error with python? copy "stdint.h" and fix "inttypes.h"

if you pip install pycrypto with python,but you get  error status,you have to fix something.

 error status

How to check Memory size of ESP32 如何確認ESP32的記憶體大小

we can use esptool to check Memory size of ESP32.

we use command  "esptool.py flash_id" to find "flash size","chip type and revision","MAC","device"

Error: Adafruit_Sensor.h: No such file with Arduino IDE (DH11) compile error

I want to use DH11 ,but compile  error.

In file included from
C:\Users\username
\Documents\Arduino\libraries\DHT_sensor_library\DHT_U.cpp:22:0:
C:\Users\username\Documents\Arduino\libraries\DHT_sensor_library\DHT_U.h:25:29: fatal error: Adafruit_Sensor.h: No such file or directory
 #include <Adafruit_Sensor.h>

You have to install "Adafruit Unified Sensor" library with arduino library manager.Maybe can fix this problem.

If you still have this problem.

you can add "#include <Adafruit_Sensor.h>" in code.

Fix arduino "exec: "cmd": executable file not found in %PATH% "

compiling code with Arduino IDE. I get a error "exec: "cmd": executable file not found in %PATH% "

PATH add %SystemRoot%\system32;%SystemRoot%;C:\Windows\System32;

How to use NodeMCU-32S Lua (ESP32) serial2 port (UART)

 NodeMCU-32S Lua have 3 UART. serial0 ,serial1, serial2.

serial	RX	TX
0	GPIO3	GPIO1
1	GPIO9	GPIO10
2	GPIO16	GPIO17

If ESP32 connect USB,only serial2 can work.

Pronterface could not connect to 3D printing "could not open port"

when we want to pc connect to 3D printing with Pronterface, but  Pronterface could not connect to 3D printing and show " could not open port" error. How to solve ?