ccb9c84db8
Use a new Duration type, which is used throughout the BLE stack for durations. The resolutions are sometimes different (connection parameters have half the resolution) but overall it should improve the ease of use of this type. This commit also provides a default advertisement interval that is recommended by Apple (which I think is as good as any recommendation). This might help to speed up discovery by Apple (and Android?) phones.
59 lines
1.5 KiB
Go
59 lines
1.5 KiB
Go
package main
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import (
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"time"
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"github.com/tinygo-org/bluetooth"
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)
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var adapter = bluetooth.DefaultAdapter
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// TODO: use atomics to access this value.
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var heartRate uint8 = 75 // 75bpm
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func main() {
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println("starting")
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must("enable BLE stack", adapter.Enable())
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adv := adapter.DefaultAdvertisement()
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must("config adv", adv.Configure(bluetooth.AdvertisementOptions{
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LocalName: "Go HRS",
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ServiceUUIDs: []bluetooth.UUID{bluetooth.New16BitUUID(0x2A37)},
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}))
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must("start adv", adv.Start())
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var heartRateMeasurement bluetooth.Characteristic
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must("add service", adapter.AddService(&bluetooth.Service{
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UUID: bluetooth.New16BitUUID(0x180D), // Heart Rate
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Characteristics: []bluetooth.CharacteristicConfig{
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{
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Handle: &heartRateMeasurement,
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UUID: bluetooth.New16BitUUID(0x2A37), // Heart Rate Measurement
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Value: []byte{0, heartRate},
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Flags: bluetooth.CharacteristicReadPermission | bluetooth.CharacteristicWritePermission,
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WriteEvent: func(client bluetooth.Connection, offset int, value []byte) {
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if offset != 0 || len(value) < 2 {
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return
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}
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if value[1] != 0 { // avoid divide by zero
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heartRate = value[1]
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println("heart rate is now:", heartRate)
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}
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},
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},
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},
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}))
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nextBeat := time.Now()
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for {
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nextBeat = nextBeat.Add(time.Minute / time.Duration(heartRate))
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println("tick", time.Now().Format("04:05.000"))
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time.Sleep(nextBeat.Sub(time.Now()))
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}
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}
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func must(action string, err error) {
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if err != nil {
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panic("failed to " + action + ": " + err.Error())
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}
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}
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