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bluetooth.go
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bluetooth.go
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package main
import (
"encoding/binary"
"fmt"
"strings"
"time"
log "github.com/sirupsen/logrus"
"github.com/go-ble/ble"
"github.com/go-ble/ble/examples/lib/dev"
"golang.org/x/net/context"
)
const (
CharPersonShort = "8a82" // person data
CharWeightShort = "8a21" // weight data
CharBodyShort = "8a22" // body data
CharCommandShort = "8a81" // command register
CharPerson = "00008a82-0000-1000-8000-00805f9b34fb" // person data
CharWeight = "00008a21-0000-1000-8000-00805f9b34fb" // weight data
CharBody = "00008a22-0000-1000-8000-00805f9b34fb" // body data
CharCommand = "00008a81-0000-1000-8000-00805f9b34fb" // command register
)
func showError(err error) {
if err == nil {
return
}
bluetoothLogger().Errorf("error: %s", err)
}
func bluetoothLogger() log.FieldLogger {
return log.WithField("component", "bluetooth")
}
// StartBluetooth runs the bluetooth cycle forever, scanning for some time and processing results
func StartBluetooth() {
d, err := dev.NewDevice(config.Device)
if err != nil {
bluetoothLogger().Fatalf("can't use device: %s", err)
}
ble.SetDefaultDevice(d)
filter := func(a ble.Advertisement) bool {
return strings.EqualFold(a.Addr().String(), config.DeviceID)
}
for {
if err := scan(filter); err != nil {
bluetoothLogger().Warnf("%s", err)
}
time.Sleep(1 * time.Second)
}
}
func scan(filter ble.AdvFilter) error {
bluetoothLogger().Infoln("starting scan...")
ctx := ble.WithSigHandler(context.WithTimeout(context.Background(), config.ScanDuration.AsTimeDuration()))
// Calculate the new timestamp by adding n seconds
newTimestamp := time.Now().Add(config.ScanDuration.AsTimeDuration())
bluetoothLogger().Infof("connecting... I should be back by %s", newTimestamp)
ch := make(chan bool, 1)
go checkBluetoothHangs(ch)
cln, err := ble.Connect(ctx, filter)
if err != nil {
ch <- false
return fmt.Errorf("scan timeout: %w", err)
}
defer disconnect(cln)
ch <- true
// Normally, the connection is disconnected by us after our exploration.
// However, it can be asynchronously disconnected by the remote peripheral.
// So we wait(detect) the disconnection in the go routine.
go func(cln ble.Client) {
select {
case <-cln.Disconnected():
bluetoothLogger().Infof("[ %s ] is disconnected ", cln.Addr())
case <-time.After(config.Sub.AsTimeDuration()):
bluetoothLogger().Infof("[ %s ] timed out", cln.Addr())
}
}(cln)
bluetoothLogger().Infof("[ %s ] is connected ...", cln.Addr())
bluetoothLogger().Infoln("discovering profile...")
p, err := cln.DiscoverProfile(true)
if err != nil {
return fmt.Errorf("can't discover profile: %w", err)
}
bluetoothLogger().Infof("address: '%s'; name: '%s'", cln.Addr(), cln.Name())
// Start the exploration.
showError(explore(cln, p))
bluetoothLogger().Infof("discovery done, waiting %.0f seconds before disconnecting.", config.Sub.AsTimeDuration().Seconds())
time.Sleep(config.Sub.AsTimeDuration())
go debounce()
return nil
}
func checkBluetoothHangs(ch chan bool) {
time.Sleep(1 * time.Second)
select {
case <-ch:
bluetoothLogger().Infof("scan finished in time")
return
case <-time.After(config.ScanDuration.AsTimeDuration()):
bluetoothLogger().Fatal("timeout")
}
}
func disconnect(cln ble.Client) {
// Disconnect the connection. (On OS X, this might take a while.)
bluetoothLogger().Infof("disconnecting [ %s ]...", cln.Addr())
showError(cln.ClearSubscriptions())
showError(cln.CancelConnection())
bluetoothLogger().Infof("disconnected!")
}
func explore(cln ble.Client, p *ble.Profile) error {
// First we subscribe to the metrics
for _, s := range p.Services {
for _, c := range s.Characteristics {
switch c.UUID.String() {
case CharWeightShort, CharBodyShort, CharPersonShort:
h := func(req []byte) { go decodeData(req) }
if err := cln.Subscribe(c, true, h); err != nil {
return fmt.Errorf("subscribe failed: %w", err)
}
}
}
}
// Then we send the current time (which triggers data transmission)
for _, s := range p.Services {
for _, c := range s.Characteristics {
if c.UUID.String() == CharCommandShort {
bluetoothLogger().Infof("sending the time... ")
binarytime := generateTime()
if err := cln.WriteCharacteristic(c, binarytime, true); err != nil {
return fmt.Errorf("error while writing command: %w", err)
}
bluetoothLogger().Infof("done.")
}
}
}
return nil
}
func generateTime() []byte {
therealtime := time.Now().Unix()
bs := make([]byte, 4)
thetime := uint32(therealtime) - 1262304000
binary.LittleEndian.PutUint32(bs, thetime)
bs = append([]byte{2}, bs...)
return bs
}