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slightly more accurate computation of the time of the last full

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revolution by using the average RPM over the last interval instead of
using the last RPM.
This commit is contained in:
Erik Brakkee 2026-06-07 23:24:19 +02:00
parent b8a9abcd2a
commit 7ee776ba1a
1 changed files with 5 additions and 2 deletions
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7
cmd/bridge/bluetooth.go
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@ -61,6 +61,7 @@ func ExposeBluetooth(events <-chan Event) {
lastUpdateTime := event.Now
var lastCompletedRevs float64 = 0.0
var lastRevTicks float64 = 0.0 // time in 1/1024s of last completed revolution
prevRpm := float64(event.Cadence)
for event := range events {
now := event.Now
@ -69,6 +70,7 @@ func ExposeBluetooth(events <-chan Event) {
watts := event.Power
rpm := float64(event.Cadence)
avgRpm := (rpm + prevRpm) / 2
totalRevs += rpm / 60.0 * deltaT
elapsedTicks += deltaT * 1024.0
@ -81,7 +83,7 @@ func ExposeBluetooth(events <-chan Event) {
// time at which the last completed revolution occurred
// = current time - fractional part of revolution * time per revolution
fracRev := totalRevs - completedRevs
ticksPerRev := 1024.0 * 60.0 / rpm
ticksPerRev := 1024.0 * 60.0 / avgRpm
lastRevTicks = elapsedTicks - fracRev*ticksPerRev
lastCompletedRevs = completedRevs
@ -90,11 +92,12 @@ func ExposeBluetooth(events <-chan Event) {
// No change we need to emit the same data ss before.
}
prevRpm = rpm
payload := make([]byte, 8)
binary.LittleEndian.PutUint16(payload[0:], bleSignalDetectedFlag)
binary.LittleEndian.PutUint16(payload[2:], watts)
binary.LittleEndian.PutUint16(payload[4:], uint16(lastCompletedRevs))
binary.LittleEndian.PutUint16(payload[6:], uint16(lastRevTicks))
binary.Little\Endian.PutUint16(payload[6:], uint16(lastRevTicks))
if _, err := powerChar.Write(payload); err != nil {
logPrintf("bt: failed to write power characteristic: %v\n", err)