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power.go
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power.go
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package main
import (
"flag"
"fmt"
rpi "github.com/Jon-Bright/ledctl/rpi"
"log"
"time"
)
var powerCtrlPin = flag.Int("powerCtrlPin", -1, "A GPIO pin which, when set high, turns on power for the LEDs. -1 means no such pin exists.")
var powerStatusPin = flag.Int("powerStatusPin", -1, "A GPIO pin which indicates healthy power to the LEDs. -1 means no such pin exists. Only relevant if powerCtrlPin is specified.")
var powerStatusWait = flag.Duration("powerStatusWait", 2*time.Second, "How long to wait for a healthy power signal. Only relevant if powerStatusPin is specified and relevant.")
func initPower(rp *rpi.RPi) error {
if *powerCtrlPin < 0 {
return nil
}
err := rp.GPIOSetOutput(*powerCtrlPin, rpi.PullNone)
if err != nil {
return fmt.Errorf("couldn't set power control to output: %v", err)
}
if *powerStatusPin < 0 {
return nil
}
return rp.GPIOSetInput(*powerStatusPin)
}
func powerOn(rp *rpi.RPi) error {
if *powerCtrlPin < 0 {
return nil
}
log.Printf("Power on")
err := rp.GPIOSetPin(*powerCtrlPin, true)
if err != nil {
return fmt.Errorf("couldn't set power control high: %v", err)
}
if *powerStatusPin < 0 {
return nil
}
start := time.Now()
for {
val, err := rp.GPIOGetPin(*powerStatusPin)
if err != nil {
return fmt.Errorf("couldn't query power status: %v", err)
}
t := time.Now()
if val {
log.Printf("Power stablized after %v", t.Sub(start))
return nil
}
if t.Sub(start) > *powerStatusWait {
return fmt.Errorf("timed out waiting for power to be healthy, started %v, now %v", start, t)
}
time.Sleep(50 * time.Millisecond) // No point overdoing it - we're not in _that_ much of a rush
}
}
func powerOff(rp *rpi.RPi) error {
if *powerCtrlPin < 0 {
return nil
}
log.Printf("Power off")
err := rp.GPIOSetPin(*powerCtrlPin, false)
if err != nil {
return fmt.Errorf("couldn't set power control low: %v", err)
}
// We could wait for power status to go low, but that might take a while and doesn't seem to provide any benefit
return nil
}