Give rpi some time to link digital pin property

kidoman / embd

Embedded Programming Framework in Go

http://embd.kidoman.io

MIT License

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Give rpi some time to link digital pin property #53

Open wujiang opened 8 years ago

wujiang commented 8 years ago

It looks like Raspberry pi needs some time to get a digital pin link properly after it is being exported.

Sample code to run:

package main

import (
        "fmt"

        "github.com/kidoman/embd"
         _ "github.com/kidoman/embd/host/rpi"
)

func main() {
        defer embd.CloseGPIO()
        fmt.Println(embd.SetDirection(10, embd.Out))
}

before the change, the output is open /sys/class/gpio/gpio10/direction: permission denied
after the change, the output is <nil>

Close #52

tve commented 7 years ago

IMHO the proper fix would not add a blind delay but use a shorter delay and check the permissions, and then loop until these change. Overall this sucks. Maybe we should add an explicit call to export a list of GPIO pins, this way they could all be exported and then it could wait for the permissions to all get fixed.