我的开发板是安信可的nodemcu-32s，看了几个源文件后，豁然开朗，终于可以按Arduino的那种方式写pin了。
先看系统的arduino-esp32/cores/esp32/Arduino.h
...
#define PI 3.1415926535897932384626433832795
#define HALF_PI 1.5707963267948966192313216916398
#define TWO_PI 6.283185307179586476925286766559
#define DEG_TO_RAD 0.017453292519943295769236907684886
#define RAD_TO_DEG 57.295779513082320876798154814105
#define EULER 2.718281828459045235360287471352
#define SERIAL 0x0
#define DISPLAY 0x1
#define LSBFIRST 0
#define MSBFIRST 1
//Interrupt Modes
#define RISING 0x01
#define FALLING 0x02
#define CHANGE 0x03
#define ONLOW 0x04
#define ONHIGH 0x05
#define ONLOW_WE 0x0C
#define ONHIGH_WE 0x0D
#define DEFAULT 1
#define EXTERNAL 0
...
这个引脚定义，是最大的收获
arduino-esp32/variants/nodemcu-32s/pins_arduino.h
#define EXTERNAL_NUM_INTERRUPTS 16
#define NUM_DIGITAL_PINS 40
#define NUM_ANALOG_INPUTS 16
#define analogInputToDigitalPin(p) (((p)<20)?(esp32_adc2gpio[(p)]):-1)
#define digitalPinToInterrupt(p) (((p)<40)?(p):-1)
#define digitalPinHasPWM(p) (p < 34)
static const uint8_t LED_BUILTIN = 2;
#define BUILTIN_LED LED_BUILTIN // backward compatibility
static const uint8_t KEY_BUILTIN = 0;
static const uint8_t TX = 1;
static const uint8_t RX = 3;
static const uint8_t SDA = 21;
static const uint8_t SCL = 22;
static const uint8_t SS = 5;
static const uint8_t MOSI = 23;
static const uint8_t MISO = 19;
static const uint8_t SCK = 18;
static const uint8_t A0 = 36;
static const uint8_t A3 = 39;
static const uint8_t A4 = 32;
static const uint8_t A5 = 33;
static const uint8_t A6 = 34;
static const uint8_t A7 = 35;
static const uint8_t A10 = 4;
static const uint8_t A11 = 0;
static const uint8_t A12 = 2;
static const uint8_t A13 = 15;
static const uint8_t A14 = 13;
static const uint8_t A15 = 12;
static const uint8_t A16 = 14;
static const uint8_t A17 = 27;
static const uint8_t A18 = 25;
static const uint8_t A19 = 26;
static const uint8_t T0 = 4;
static const uint8_t T1 = 0;
static const uint8_t T2 = 2;
static const uint8_t T3 = 15;
static const uint8_t T4 = 13;
static const uint8_t T5 = 12;
static const uint8_t T6 = 14;
static const uint8_t T7 = 27;
static const uint8_t T8 = 33;
static const uint8_t T9 = 32;
static const uint8_t DAC1 = 25;
static const uint8_t DAC2 = 26;
