raspberry-pi3 - 我如何通过 i2c 从 Rpi 作为主机将多个浮点数据写入 Arduino？

Question

我读了很多帖子 Rpi 如何通过 Arduino 通过 i2c 接收浮点数据，Rpi 作为主控。

但我需要将浮点值写入 arduino，但我没有找到任何示例。我想使用 python smbus。

任何人有一个例子？

非常感谢！

Answer 1

经过多次测试，我可以在作为从机的 arduino 和作为主机的 Raspberry pi3 之间交换多个数据。

Arduino代码：

#include <Wire.h>
byte data[12];
int command;

typedef struct processData{
  float temp1;
  float temp2;
  float temp3;
  float temp4;
  float vazao_quente;
  float vazao_fria;
  byte pump_speed;
  //bool  pump_status;
  byte bstatus;
  //bool heater_status;
  byte chksum;
};

typedef union I2C_Send{
  processData data;
  byte I2C_packet[sizeof(processData)];
};


I2C_Send send_info;


void parseValues(byte data[]){
  union float_tag{
    byte b[4];
    float fval;
  }ft;

  ft.b[0] =data[1];
  ft.b[1] = data[2];
  ft.b[2] = data[3];
  ft.b[3] = data[4];

  Serial.println(ft.fval);
}

void setup()
{
  Wire.begin(12);                // join i2c bus with address #4
  Wire.onReceive(receiveEvent); // register event
  Wire.onRequest(requestEvent);
  Serial.begin(9600);           // start serial for output
  setrnddata();
}

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)
{
  command = Wire.read();
  if (command==1){
    int i=0;
    while(1 <= Wire.available()) // loop through all but the last
    {
      data[i] = Wire.read(); // receive byte as a character
      i = i+1;
    }
    parseValues(data);
  }
}

void requestEvent()
{
    if(command==2){
      Wire.write(send_info.I2C_packet,sizeof(processData));
    }
}

树莓派代码：

from datetime import datetime
from datetime import timedelta
from smbus import SMBus
import struct

start_time = datetime.now()

def millis():
    dt = datetime.now()-start_time
    ms = (dt.days*24*60*60 + dt.seconds)*1000+dt.microseconds / 1000.0  
    return ms

#inicia escravo i2c
bus = SMBus(1) 
arduinoAddress = 12

#interval request
interval = 150

temperatura = 10.2
vazao = 5.3
command = 20
teste = 30

if __name__ == '__main__':
    prevmillis = millis()

    while True:
        currentmillis = millis()
        if(currentmillis - prevmillis > interval):

            #write

            bytescommand = struct.pack('=2fbb',temperatura,vazao,command,teste)
            bus.write_block_data(arduinoAddress,1,list(bytescommand))
            print(list(bytescommand))

            #request
            block = bus.read_i2c_block_data(arduinoAddress,2,27)
            output = struct.unpack('6f3b',bytes(block))
            print(output)
            print(datetime.now().strftime('%Y-%m-%d %H:%M:%S.%f')[:-3])
            prevmillis = currentmillis

我希望能帮助别人！谢谢！