使用 I2C 到 Arduino 的 Android Things - 错误 6：没有这样的设备或地址

Question

我尝试使用 I2C 将运行 Android Things 的 NXP i.MX7D 连接到 Arduino UNO。从属代码相当简单：

#include <Wire.h>

void setup() {
  Wire.begin(0x08);                // join i2c bus with address #8
  Wire.onRequest(requestEvent); // register event
}

void loop() {
  delay(100);
}

// function that executes whenever data is requested by master
// this function is registered as an event, see setup()
void requestEvent() {
  Wire.write("hello "); // respond with message of 6 bytes
  // as expected by master
}

两个设备是这样连接的：

NPX SDA Pin ---> 3.3v 电平转换器 5v ----> Arduino PIN A4 NPX SCL Pin ---> 3.3v 电平转换器 5v ----> Arduino PIN A5

当我使用 PIO 工具时，我似乎无法连接或读取 Arduino 从站。 NPX上有两个BUS（I2C1，I2C2）我都试过了，结果一样：

imx7d_pico:/ $ pio i2c I2C1 0x08 read-reg-byte 0x00                                                                   
[WARNING:client_errors.cc(35)] error 6: No such device or address
6|imx7d_pico:/ $ pio i2c I2C2 0x08 read-reg-byte 0x00                                                                 
[WARNING:client_errors.cc(35)] error 6: No such device or address

我假设电平转换器工作正常我确实在 UART 连接方面取得了有限的成功（Arduino 能够发射到 NPX，但不能发射到 Arduino，稍后将对此进行调查）

这里是一些连接的图片。

Answer 1

尝试添加 Wire.onReceive 回调（连同 onRequest）到您的 arduino 代码。

像这样：

#include <Wire.h>

void setup() {
  Wire.begin(8);                // join i2c bus with address #8
  Wire.onReceive(receiveEvent); // register event
  Serial.begin(9600);           // start serial for output
}

void loop() {
  delay(100);
}

// function that executes whenever data is received from master
// this function is registered as an event, see setup()
void receiveEvent(int howMany) {
  while (1 < Wire.available()) { // loop through all but the last
    char c = Wire.read(); // receive byte as a character
    Serial.print(c);         // print the character
  }
  int x = Wire.read();    // receive byte as an integer
  Serial.println(x);         // print the integer
}