treatment: add support for digital volume control

cmd/treatment/main.go

@@ -46,6 +46,7 @@ import (
 	"bitbucket.org/ausocean/iot/pi/netlogger"
 	"bitbucket.org/ausocean/iot/pi/netsender"
 	"bitbucket.org/ausocean/utils/logger"
+	"github.com/kidoman/embd"
 	_ "github.com/kidoman/embd/host/rpi"
 	lumberjack "gopkg.in/natefinch/lumberjack.v2"
 )
@@ -71,6 +72,9 @@ const (
 	netSendRetryTime = 5 * time.Second
 	defaultSleepTime = 60 // Seconds
 	pkg              = "rv: "
+	minAmpVolume     = 0
+	maxAmpVolume     = 63
+	volAddr          = 0x4B
 )
 
 // Treatment modes.
@@ -184,6 +188,23 @@ func run(rv *revid.Revid, ns *netsender.Sender, file *string, l *logger.Logger,
 		}
 		l.Info("revid successfully reconfigured")
 
+		l.Debug("checking amplifier volume")
+		v := vars["AmpVolume"]
+		if v != "" {
+			vol, err := strconv.ParseInt(v, 10, 8)
+			if err != nil {
+				l.Error(pkg+"failed to parse amplifier volume", "error", err.Error())
+			} else if vol < minAmpVolume || vol > maxAmpVolume {
+				l.Error(fmt.Sprintf("%s invalid amplifier volume, must be between %v and %v", pkg, minAmpVolume, maxAmpVolume), "volume", vol)
+			} else {
+				bus := embd.NewI2CBus(1)
+				err := bus.WriteByte(volAddr, byte(vol))
+				if err != nil {
+					l.Error(pkg+"failed to write amplifier volume", "error", err.Error())
+				}
+			}
+		}
+
 		l.Debug("checking mode")
 		switch ns.Mode() {
 		case modePaused: