104 lines
2.9 KiB
Go
104 lines
2.9 KiB
Go
// This example scans and then connects to a specific Bluetooth peripheral
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// that can provide the Heart Rate Service (HRS).
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//
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// Once connected, it subscribes to notifications for the data value, and
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// displays it.
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// The Heart Rate Measurement characteristic is a variable-length structure (array) containing a Flags field, a Heart
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// Rate Measurement Value field and, based on the contents of the Flags field, may contain additional fields
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// such as Energy Expended or RR-Interval.
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// More info can be found here: https://www.bluetooth.com/specifications/specs/gatt-specification-supplement-6/
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// In this example only the heart rate is used, this is the second element in the array of bytes.
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//
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// To run this on a desktop system:
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//
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// go run ./examples/heartrate-monitor EE:74:7D:C9:2A:68
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//
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// To run this on a microcontroller, change the constant value in the file
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// "mcu.go" to set the MAC address of the device you want to discover.
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// Then, flash to the microcontroller board like this:
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//
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// tinygo flash -o circuitplay-bluefruit ./examples/heartrate-monitor
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//
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// Once the program is flashed to the board, connect to the USB port
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// via serial to view the output.
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package main
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import (
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"gitrepo.ru/neonxp/bluetooth"
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)
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var (
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adapter = bluetooth.DefaultAdapter
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heartRateServiceUUID = bluetooth.ServiceUUIDHeartRate
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heartRateCharacteristicUUID = bluetooth.CharacteristicUUIDHeartRateMeasurement
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)
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func main() {
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println("enabling")
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// Enable BLE interface.
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must("enable BLE stack", adapter.Enable())
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ch := make(chan bluetooth.ScanResult, 1)
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// Start scanning.
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println("scanning...")
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err := adapter.Scan(func(adapter *bluetooth.Adapter, result bluetooth.ScanResult) {
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println("found device:", result.Address.String(), result.RSSI, result.LocalName())
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if result.Address.String() == connectAddress() {
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adapter.StopScan()
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ch <- result
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}
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})
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var device bluetooth.Device
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select {
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case result := <-ch:
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device, err = adapter.Connect(result.Address, bluetooth.ConnectionParams{})
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if err != nil {
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println(err.Error())
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return
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}
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println("connected to ", result.Address.String())
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}
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// get services
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println("discovering services/characteristics")
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srvcs, err := device.DiscoverServices([]bluetooth.UUID{heartRateServiceUUID})
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must("discover services", err)
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if len(srvcs) == 0 {
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panic("could not find heart rate service")
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}
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srvc := srvcs[0]
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println("found service", srvc.UUID().String())
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chars, err := srvc.DiscoverCharacteristics([]bluetooth.UUID{heartRateCharacteristicUUID})
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if err != nil {
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println(err)
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}
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if len(chars) == 0 {
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panic("could not find heart rate characteristic")
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}
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char := chars[0]
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println("found characteristic", char.UUID().String())
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char.EnableNotifications(func(buf []byte) {
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println("data:", uint8(buf[1]))
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})
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select {}
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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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