Just switched from Arduino UNO to ESP32, problems everywhere, take note. Like in the picture above I bought two boards. (Actually more than two, these are the only two I’ve played these days. There’s also an ESP32-CAM with a camera)
Problems encountered
Write programs
Connecting…. was found when uploading the program When you need to press the boot button to write a program, see the program to loosen it. (ESP32 DEVKITV1 requires this operation, Wemos D1 R32 does not need this operation.) If you encounter an upload error, you may need to unplug your 3.3V cable to write the application
2. Wemos D1 R32 is hard to find. I can’t find any pin diagrams. 
 
benefits
Use a 0.96 “OLED
You can directly use u8G2_FONt_wqy12_T_GB2312B to display Chinese. Use three libraries. Io21 ->SDA io22 -> SCL (note: Wemos D1 R32 SDA SCL is not debugable)
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <U8g2_for_Adafruit_GFX.h>
The interface problem
Not all connections are available for the ESP32
Eight GPIO
IO12IO13IO14IO27IO33IO32IO4IO5
The I2C interface
I2C bus is a simple bidirectional two-wire synchronous serial bus developed by Philips Company.
IO22 SCLIO21 SDA
UART2(Universal Asynchronous Transceiver) interface
Note: rx0 and TX0 on the board are used to download programs. RX2 and TX2 on the board
IO16 RXIO17 TX
VSPI(SPI: Serial peripheral Interface)
IO5 CS0* IO18 SCLKIO23 MOSIIO19 MISO
HSPI(another SPI interface)
IO15 CS0* IO14 SCLKIO13 MOSIIO12 MISO
Analog pin
DAC digital to analog ADC analog to digital
IO25 DAC1 ADC (left channel)IO26 DAC2 ADC (right channel)I34 ADCI36 ADC