【コード付き】ESP32のI2C。I2CScanner と 0.56″ 7-Segmentの使い方。

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

void setup() {
  Serial.begin(115200);
  Wire.begin();
}
void loop() {
  byte error, address;
  int nDevices = 0;

  delay(5000);

  Serial.println("Scanning for I2C devices ...");
  for(address = 0x01; address < 0x7f; address++){
    Wire.beginTransmission(address);
    error = Wire.endTransmission();
    if (error == 0){
      Serial.printf("I2C device found at address 0x%02X\n", address);
      nDevices++;
    } else if(error != 2){
      Serial.printf("Error %d at address 0x%02X\n", error, address);
    }
  }
  if (nDevices == 0){
    Serial.println("No I2C devices found");
  }
}

// Master Begin
bool TwoWire::begin(int sdaPin, int sclPin, uint32_t frequency)

esp_err_t i2cInit(uint8_t i2c_num, int8_t sda, int8_t scl, uint32_t frequency)

    i2c_config_t conf = { };
    conf.mode = I2C_MODE_MASTER;
    conf.scl_io_num = (gpio_num_t)scl;
    conf.sda_io_num = (gpio_num_t)sda;
    conf.scl_pullup_en = GPIO_PULLUP_ENABLE;
    conf.sda_pullup_en = GPIO_PULLUP_ENABLE;
    conf.master.clk_speed = frequency;
    conf.clk_flags = I2C_SCLK_SRC_FLAG_FOR_NOMAL; //Any one clock source that is available for the specified frequency may be choosen

#include <Arduino.h>

/***************************************************
  This is a library for our I2C LED Backpacks

  Designed specifically to work with the Adafruit LED 7-Segment backpacks
  ----> http://www.adafruit.com/products/881
  ----> http://www.adafruit.com/products/880
  ----> http://www.adafruit.com/products/879
  ----> http://www.adafruit.com/products/878

  These displays use I2C to communicate, 2 pins are required to
  interface. There are multiple selectable I2C addresses. For backpacks
  with 2 Address Select pins: 0x70, 0x71, 0x72 or 0x73. For backpacks
  with 3 Address Select pins: 0x70 thru 0x77

  Adafruit invests time and resources providing this open source code,
  please support Adafruit and open-source hardware by purchasing
  products from Adafruit!

  Written by Limor Fried/Ladyada for Adafruit Industries.
  BSD license, all text above must be included in any redistribution
 ****************************************************/

#include <Wire.h> // Enable this line if using Arduino Uno, Mega, etc.
#include <SPI.h>
#include <Adafruit_GFX.h>
#include "Adafruit_LEDBackpack.h"

Adafruit_7segment matrix = Adafruit_7segment();

void setup()
{
#ifndef __AVR_ATtiny85__
  Serial.begin(9600);
  Serial.println("7 Segment Backpack Test");
#endif
  matrix.begin(0x70);
}

void loop()
{
  // try to print a number thats too long
  matrix.print(10000, DEC);
  matrix.writeDisplay();
  delay(500);

  // print a hex number
  matrix.print(0xBEEF, HEX);
  matrix.writeDisplay();
  delay(500);

  // print a floating point
  matrix.print(12.34);
  matrix.writeDisplay();
  delay(500);

  // print a string message
  matrix.print("7SEG");
  matrix.writeDisplay();
  delay(10000);

  // print with print/println
  for (uint16_t counter = 0; counter < 9999; counter++)
  {
    matrix.println(counter);
    matrix.writeDisplay();
    delay(10);
  }

  // method #2 - draw each digit
  uint16_t blinkcounter = 0;
  boolean drawDots = false;
  for (uint16_t counter = 0; counter < 9999; counter++)
  {
    matrix.writeDigitNum(0, (counter / 1000), drawDots);
    matrix.writeDigitNum(1, (counter / 100) % 10, drawDots);
    matrix.drawColon(drawDots);
    matrix.writeDigitNum(3, (counter / 10) % 10, drawDots);
    matrix.writeDigitNum(4, counter % 10, drawDots);

    blinkcounter += 50;
    if (blinkcounter < 500)
    {
      drawDots = false;
    }
    else if (blinkcounter < 1000)
    {
      drawDots = true;
    }
    else
    {
      blinkcounter = 0;
    }
    matrix.writeDisplay();
    delay(10);
  }
}