086c797e0f
This changes the previous raw advertisement packets to structured advertisement configuration. That means you can set the local name not with a raw byte array but with a normal string. While this departs a bit from the original low-level interface as is often used on microcontroller BLE stacks, it is certainly easier to use and better matches higher level APIs that are commonly provided by general-purpose operating systems. If there is a need for raw BLE packets (for baremetal systems only), this can easily be added in the future.
130 lines
3.7 KiB
Go
130 lines
3.7 KiB
Go
// +build softdevice,!s110v8
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package bluetooth
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import (
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"device/arm"
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"runtime/volatile"
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)
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/*
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// Define SoftDevice functions as regular function declarations (not inline
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// static functions).
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#define SVCALL_AS_NORMAL_FUNCTION
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#include "ble_gap.h"
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*/
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import "C"
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// Memory buffers needed by sd_ble_gap_scan_start.
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var (
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scanReportBuffer rawAdvertisementPayload
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gotScanReport volatile.Register8
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globalScanResult ScanResult
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)
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// Advertisement encapsulates a single advertisement instance.
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type Advertisement struct {
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handle uint8
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}
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// NewAdvertisement creates a new advertisement instance but does not configure
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// it. It can be called before the SoftDevice has been initialized.
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func (a *Adapter) NewAdvertisement() *Advertisement {
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return &Advertisement{
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handle: C.BLE_GAP_ADV_SET_HANDLE_NOT_SET,
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}
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}
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// Configure this advertisement. Must be called after SoftDevice initialization.
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func (a *Advertisement) Configure(options AdvertisementOptions) error {
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data := C.ble_gap_adv_data_t{}
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var payload rawAdvertisementPayload
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payload.addFlags(0x06)
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if options.LocalName != "" {
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if !payload.addCompleteLocalName(options.LocalName) {
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return errAdvertisementPacketTooBig
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}
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}
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data.adv_data = C.ble_data_t{
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p_data: &payload.data[0],
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len: uint16(payload.len),
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}
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params := C.ble_gap_adv_params_t{
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properties: C.ble_gap_adv_properties_t{
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_type: C.BLE_GAP_ADV_TYPE_CONNECTABLE_SCANNABLE_UNDIRECTED,
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},
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interval: uint32(options.Interval),
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}
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errCode := C.sd_ble_gap_adv_set_configure(&a.handle, &data, ¶ms)
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return makeError(errCode)
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}
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// Start advertisement. May only be called after it has been configured.
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func (a *Advertisement) Start() error {
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errCode := C.sd_ble_gap_adv_start(a.handle, C.BLE_CONN_CFG_TAG_DEFAULT)
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return makeError(errCode)
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}
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// Scan starts a BLE scan. It is stopped by a call to StopScan. A common pattern
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// is to cancel the scan when a particular device has been found.
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func (a *Adapter) Scan(callback func(*Adapter, ScanResult)) error {
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if a.scanning {
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// There is a possible race condition here if Scan() is called from a
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// different goroutine, but that is not allowed (and will likely result
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// in an error below anyway).
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return errScanning
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}
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a.scanning = true
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scanParams := C.ble_gap_scan_params_t{}
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scanParams.set_bitfield_extended(0)
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scanParams.set_bitfield_active(0)
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scanParams.interval = 100 * 1000 / 625 // 100ms in 625µs units
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scanParams.window = 100 * 1000 / 625 // 100ms in 625µs units
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scanParams.timeout = C.BLE_GAP_SCAN_TIMEOUT_UNLIMITED
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scanReportBufferInfo := C.ble_data_t{
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p_data: &scanReportBuffer.data[0],
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len: uint16(len(scanReportBuffer.data)),
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}
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errCode := C.sd_ble_gap_scan_start(&scanParams, &scanReportBufferInfo)
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if errCode != 0 {
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return Error(errCode)
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}
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// Wait for received scan reports.
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for a.scanning {
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// Wait for the next advertisement packet to arrive.
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// TODO: use some sort of condition variable once the scheduler supports
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// them.
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arm.Asm("wfe")
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if gotScanReport.Get() == 0 {
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// Spurious event. Continue waiting.
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continue
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}
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gotScanReport.Set(0)
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// Call the callback with the scan result.
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callback(a, globalScanResult)
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// Restart the advertisement. This is needed, because advertisements are
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// automatically stopped when the first packet arrives.
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errCode := C.sd_ble_gap_scan_start(nil, &scanReportBufferInfo)
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if errCode != 0 {
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return Error(errCode)
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}
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}
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return nil
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}
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// StopScan stops any in-progress scan. It can be called from within a Scan
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// callback to stop the current scan. If no scan is in progress, an error will
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// be returned.
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func (a *Adapter) StopScan() error {
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if !a.scanning {
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return errNotScanning
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}
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a.scanning = false
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return nil
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}
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