開發環境

操作系統：OpenEuler
硬件：樹莓派4B,PCF8591
開發語言：Golang

Openeuler 啟用I2C

相關配置文件
/boot/config.txt

dtparam=i2c_arm=on
dtparam=i2c_baudrate=10000

相關命令

sudo modprobe i2c-core
sudo modprobe i2c-dev

I2C工具安裝

下載地址
https://mirrors.edge.kernel.org/pub/software/utils/i2c-tools/

操作命令

sudo i2cdetect -l  # 列出所有I2C總線
sudo i2cdetect -y 0  # 假設你的I2C設備連接在總線0上
sudo i2cdump -y 0 0x38  # 假設你的I2C設備地址是0x38

測試代碼

pcf8591.go

package pcf8591

import (
    "periph.io/x/conn/v3"
    "periph.io/x/conn/v3/i2c"
)

// Channel 模擬信號輸入
type Channel uint8

// AIN0～AIN3 模擬信號輸入端
const (
    AIO0 Channel = 0
    AIO1 Channel = 1
    AIO2 Channel = 2
    AIO3 Channel = 3
)

// Dev is a handle to an initialized PCF8591 device.
type Dev struct {
    d    conn.Conn
    name string
}

// NewI2C returns an object that communicates over I2C to PCF8591
func NewI2C(b i2c.Bus, addr uint16) (*Dev, error) {
    d := &Dev{d: &i2c.Dev{Bus: b, Addr: addr}}
    return d, nil
}

// Read 讀取結果
func (d *Dev) Read(channel Channel) (result byte) {
    tmp := make([]byte, 1)
    switch channel {
    case AIO0:
        d.d.Tx([]byte{0x40}, tmp)
    case AIO1:
        d.d.Tx([]byte{0x41}, tmp)
    case AIO2:
        d.d.Tx([]byte{0x42}, tmp)
    case AIO3:
        d.d.Tx([]byte{0x43}, tmp)
    }
    result = tmp[0]
    return
}

// Write 寫入數據
func (d *Dev) Write(val byte) {
    d.d.Tx([]byte{0x40, val}, nil)
}

main.go

package main

import (
    "ez-pi/pcf8591"
    "log"
    "periph.io/x/conn/v3/i2c/i2creg"
    "periph.io/x/host/v3"
    "time"
)

func main() {
    // 加載所有驅動
    if _, err := host.Init(); err != nil {
        log.Fatal(err)
    }

    // 打開第一個可用I2C總線的handle
    //bus, err := i2creg.Open("/dev/i2c/1")
    bus, err := i2creg.Open("")
    if err != nil {
        log.Fatal(err)
    }
    defer bus.Close()

    // 通過執行命令 'sudo i2cdetect -y 1' 查看 PCF8591 設備地址
    dev, err := pcf8591.NewI2C(bus, 0x48)
    if err != nil {
        log.Fatal(err)
    }

    var tmp1 byte
    var tmp2 uint16
    for {
        // 讀取可調電阻值
        tmp1 = dev.Read(pcf8591.AIO0)
        tmp2 = BytesToUint16([]byte{tmp1})
        // LED燈亮度值125~255
        tmp2 = tmp2*(255-125)/255 + 125
        // 調節LED燈的亮度
        dev.Write(Uint16ToBytes(tmp2)[0])

        log.Println(tmp1)
        // 亮度為0時退出程序
        if tmp1 == 0 {
            break
        }
        time.Sleep(50)
    }
}

// Uint16ToBytes unit16 -> bytes
func Uint16ToBytes(n uint16) []byte {
    return []byte{
        byte(n),
        byte(n >> 8),
    }
}

// BytesToUint16 bytes -> unit16
func BytesToUint16(array []byte) uint16 {
    var data uint16 = 0
    for i := 0; i < len(array); i++ {
        data = data + uint16(uint(array[i])<<uint(8*i))
    }

    return data
}