DMAC/internal/pkg/I2C/bus.go

package I2C

// file has general wrappers to interact with i2c-tools

import (
    "fmt"
    _ "log"
    "encoding/hex"
    "os/exec"
    "bytes"
    "strings"
    "sync"
    "strconv"
    "FRMS/internal/pkg/logging"
)

type I2CBus struct {
    int
    sync.Mutex
}

func NewBus(bus int) *I2CBus {
    b := &I2CBus{}
    b.int = bus
    return b
}

func (b *I2CBus) Scan() map[int]bool {
    /*
    Returns all the connected devices
    */
    b.Lock()
    defer b.Unlock()
    bus := strconv.Itoa(b.int)
    cmd := exec.Command("i2cdetect", "-y", "-r", bus)
    var out bytes.Buffer
    var errs bytes.Buffer
    cmd.Stderr = &errs
    cmd.Stdout = &out
    if err := cmd.Run(); err != nil {
        logging.Debug(logging.DError, "I2C error performing scan. %v", errs.String())
    }

    outString := out.String()
    // could split by \n too
    split := strings.SplitAfter(outString,":")
    // 1st entry is garbage headers and ending is always \n##:
    split = split[1:]
    // create empty slice for all the devices
    //var devices []i2cdev
    devices := map[int]bool{} //maps device addresses to active bool
    for i,v := range split {
        lst := strings.Index(v,"\n")
        trimmed := v[:lst]
        trimmed = strings.Trim(trimmed," ")
        // trimmed now holds just possible sensor addresses
        count := strings.Split(trimmed," ")
        for j,d := range count {
            // the first row has to be offset by 3 but after its just i*16 + j
            offset := 0
            if i == 0 {
                offset = 3
            }
            addr := i*16 + j + offset
            if strings.Contains(d,"--") || strings.Contains(d,"UU") {
                // address is unconnected or reserved
                //devices = append(devices, I2Cdev{Addr:addr,Active:false})
                devices[addr] = false
            } else {
                //devices = append(devices, I2Cdev{Addr:addr,Active:true,LastSeen:now})
                devices[addr] = true
            }
        }
    }
    return devices
}

func (b *I2CBus) GetStatus(addr int) bool {
    b.Lock()
    defer b.Unlock()

    bus := strconv.Itoa(b.int)
    a := strconv.Itoa(addr)
    cmd := exec.Command("i2cdetect","-y","-r",bus,a,a)
    var out bytes.Buffer
    var errs bytes.Buffer
    cmd.Stderr = &errs
    cmd.Stdout = &out
    if err := cmd.Run(); err != nil {
        logging.Debug(logging.DError,"I2C error getting status! %v", errs.String())
    }

    outString := out.String()
    split := strings.SplitAfter(outString,":")
    split = split[1:] // remove garbage header
    val := int(addr/16)     // if addr = 90 90/16 = int(5.6) = 5 will be in 5th row
    dev := split[val]
    lst := strings.Index(dev,"\n")
    dev = dev[:lst]
    trimmed := strings.Trim(dev," \n")
    if strings.Contains(trimmed,"--") {
        return false
    } else {
        return true
    }
}

func (b *I2CBus) GetData(addr int) string {
    b.Lock()
    defer b.Unlock()

    bus := strconv.Itoa(b.int)
    a := strconv.FormatInt(int64(addr),16)
    cmd := exec.Command("i2ctransfer","-y",bus,fmt.Sprintf("r40@0x%s",a))
    var out bytes.Buffer
    var errs bytes.Buffer
    cmd.Stderr = &errs
    cmd.Stdout = &out
    if err := cmd.Run(); err != nil {
        logging.Debug(logging.DError,"I2C error getting data! %v", errs.String())
    }

    outString := out.String()
    split := strings.SplitAfter(outString," ") //getting chars 0x12 0x2f etc
    var final string
    for _,v := range split {
        trimmed := strings.TrimLeft(v, "0x ") // trimming extra bs in front of num
        trimmed = strings.TrimRight(trimmed," \n") // trimming back
        if trimmed != "ff" {
            final += trimmed
        }
    }
    ret, err := hex.DecodeString(final)
    if err != nil {
        panic(err)
    }
    return string(ret)
}