Files
saphid--frame-control/scripts/heart-test-strap.swift
saphidandClaude Opus 5.5 fa49fab5bf feat(tracking): experimental eye-camera pulse estimate and heart-rate comparison tool
Adds 'pulse', which captures the IR eye cameras through SteamVR's own
eyetracking --calib mode, reduces each image to patch averages and deletes it
immediately, then estimates pulse from skin brightness. Adds heart-check.py to
show OSC readings live and compare recordings with an Apple Health export or
CSV, and a synthetic Mac BLE strap for relay tests.

Part of #27

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
2026-09-29 12:15:05 +10:00

101 lines
4.4 KiB
Swift

// A synthetic Bluetooth heart-rate strap for testing, run on the Mac.
//
// swiftc -O scripts/heart-test-strap.swift -o /tmp/heart-test-strap
// /tmp/heart-test-strap [seconds] # default 60
//
// Advertises the standard Heart Rate Service (180d) as "FC Test Strap" and,
// while a central is subscribed, sends one Heart Rate Measurement (2a37) per
// second from a fixed, known sequence. Each sent value is printed to stdout as
// `unix_seconds,bpm,flags` so scripts/heart-check.py can compare what the
// Frame received with what was sent. Every value is synthetic; this is not a
// sensor. macOS asks for Bluetooth permission the first time it runs.
import CoreBluetooth
import Foundation
let hrs = CBUUID(string: "180D")
let measurement = CBUUID(string: "2A37")
/// The known sequence: an 8-bit ramp, 16-bit encodings, a skin-contact loss
/// (which must show as no reading) and a recovery.
func packet(_ second: Int) -> (bpm: Int, flags: UInt8) {
switch second % 60 {
case 0..<30: return (60 + second % 60 * 4, 0x06) // 60…176, contact detected
case 30..<40: return (180 - (second % 60 - 30) * 3, 0x07) // 16-bit value
case 40..<45: return (150, 0x04) // contact lost
default: return (72 + (second % 60 - 45), 0x06)
}
}
final class Strap: NSObject, CBPeripheralManagerDelegate {
let seconds: Int
var manager: CBPeripheralManager!
var characteristic: CBMutableCharacteristic!
var subscribed = false
var sent = 0
init(seconds: Int) {
self.seconds = seconds
super.init()
manager = CBPeripheralManager(delegate: self, queue: nil)
}
func peripheralManagerDidUpdateState(_ peripheral: CBPeripheralManager) {
guard peripheral.state == .poweredOn else {
FileHandle.standardError.write("Bluetooth state \(peripheral.state.rawValue)\n".data(using: .utf8)!)
if peripheral.state == .unauthorized || peripheral.state == .unsupported || peripheral.state == .poweredOff {
FileHandle.standardError.write("Bluetooth unavailable (state \(peripheral.state.rawValue))\n".data(using: .utf8)!)
exit(1)
}
return
}
characteristic = CBMutableCharacteristic(type: measurement, properties: [.notify], value: nil, permissions: [])
let service = CBMutableService(type: hrs, primary: true)
service.characteristics = [characteristic]
peripheral.add(service)
}
func peripheralManager(_ peripheral: CBPeripheralManager, didAdd service: CBService, error: Error?) {
if let error { fail("add service: \(error.localizedDescription)") }
peripheral.startAdvertising([CBAdvertisementDataLocalNameKey: "FC Test Strap",
CBAdvertisementDataServiceUUIDsKey: [hrs]])
}
func peripheralManagerDidStartAdvertising(_ peripheral: CBPeripheralManager, error: Error?) {
if let error { fail("advertise: \(error.localizedDescription)") }
FileHandle.standardError.write("Advertising FC Test Strap\n".data(using: .utf8)!)
Timer.scheduledTimer(withTimeInterval: 1, repeats: true) { _ in self.tick() }
}
func peripheralManager(_ peripheral: CBPeripheralManager, central: CBCentral, didSubscribeTo characteristic: CBCharacteristic) {
subscribed = true
FileHandle.standardError.write("Central subscribed\n".data(using: .utf8)!)
}
func peripheralManager(_ peripheral: CBPeripheralManager, central: CBCentral, didUnsubscribeFrom characteristic: CBCharacteristic) {
subscribed = false
FileHandle.standardError.write("Central unsubscribed\n".data(using: .utf8)!)
}
func tick() {
guard subscribed else { return }
if sent >= seconds { exit(0) }
let (bpm, flags) = packet(sent)
var bytes: [UInt8] = [flags, UInt8(bpm & 0xff)]
if flags & 1 != 0 { bytes.append(UInt8(bpm >> 8)) }
if manager.updateValue(Data(bytes), for: characteristic, onSubscribedCentrals: nil) {
print(String(format: "%.3f,%d,%d", Date().timeIntervalSince1970, bpm, flags))
fflush(stdout)
sent += 1
}
}
func fail(_ message: String) -> Never {
FileHandle.standardError.write("\(message)\n".data(using: .utf8)!)
exit(1)
}
}
let seconds = CommandLine.arguments.count > 1 ? Int(CommandLine.arguments[1]) ?? 60 : 60
let strap = Strap(seconds: seconds)
RunLoop.main.run()