public static IObservable <ushort> WhenHeartRateBpm(this IPeripheral peripheral) => peripheral
.WhenConnectedGetKnownService(HeartRateServiceUuid)
.Select(x => x.DiscoverCharacteristics())
.Switch()
.Take(1)
.Select(x => x.ReadInterval(TimeSpan.FromSeconds(3)))
.Switch()
.Select(x =>
{
if ((x.Data[0] & 0x01) == 0)
{
return((ushort)x.Data[1]);
}
var bpm = (ushort)x.Data[1];
bpm = (ushort)(((bpm >> 8) & 0xFF) | ((bpm << 8) & 0xFF00));
return(bpm);
});