Atomic HRS reads (#1845)
- Combine the reading of all `HRS3300` registers into one I2C read so data is not partial - Downsizes both HRS and ALS to 16bit as the sensor does not generate larger than 16bit values in its current configuration - Increasing the resolution by 1 bit doubles the sensor acquisition time, since we are already at 10Hz we are never going to use a higher resolution - The PPG algorithm buffers for ALS/HRS are already 16bit anyway - Remove functions for setting gain / drive that are unused throughout the codebase - Calculate constants with constexpr
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@ -142,7 +142,7 @@ Ppg::Ppg() {
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spectrum.fill(0.0f);
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}
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int8_t Ppg::Preprocess(uint32_t hrs, uint32_t als) {
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int8_t Ppg::Preprocess(uint16_t hrs, uint16_t als) {
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if (dataIndex < dataLength) {
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dataHRS[dataIndex++] = hrs;
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}
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@ -14,7 +14,7 @@ namespace Pinetime {
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class Ppg {
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public:
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Ppg();
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int8_t Preprocess(uint32_t hrs, uint32_t als);
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int8_t Preprocess(uint16_t hrs, uint16_t als);
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int HeartRate();
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void Reset(bool resetDaqBuffer);
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static constexpr int deltaTms = 100;
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@ -67,40 +67,37 @@ void Hrs3300::Disable() {
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WriteRegister(static_cast<uint8_t>(Registers::PDriver), 0);
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}
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uint32_t Hrs3300::ReadHrs() {
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auto m = ReadRegister(static_cast<uint8_t>(Registers::C0DataM));
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auto h = ReadRegister(static_cast<uint8_t>(Registers::C0DataH));
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auto l = ReadRegister(static_cast<uint8_t>(Registers::C0dataL));
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return ((l & 0x30) << 12) | (m << 8) | ((h & 0x0f) << 4) | (l & 0x0f);
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Hrs3300::PackedHrsAls Hrs3300::ReadHrsAls() {
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constexpr Registers dataRegisters[] =
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{Registers::C1dataM, Registers::C0DataM, Registers::C0DataH, Registers::C1dataH, Registers::C1dataL, Registers::C0dataL};
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// Calculate smallest register address
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constexpr uint8_t baseOffset = static_cast<uint8_t>(*std::min_element(std::begin(dataRegisters), std::end(dataRegisters)));
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// Calculate largest address to determine length of read needed
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// Add one to largest relative index to find the length
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constexpr uint8_t length = static_cast<uint8_t>(*std::max_element(std::begin(dataRegisters), std::end(dataRegisters))) - baseOffset + 1;
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Hrs3300::PackedHrsAls res;
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uint8_t buf[length];
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auto ret = twiMaster.Read(twiAddress, baseOffset, buf, length);
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if (ret != TwiMaster::ErrorCodes::NoError) {
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NRF_LOG_INFO("READ ERROR");
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}
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// hrs
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uint8_t m = static_cast<uint8_t>(Registers::C0DataM) - baseOffset;
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uint8_t h = static_cast<uint8_t>(Registers::C0DataH) - baseOffset;
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uint8_t l = static_cast<uint8_t>(Registers::C0dataL) - baseOffset;
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// There are two extra bits (17 and 18) but they are not read here
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// as resolutions >16bit aren't practically useful (too slow) and
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// all hrs values throughout InfiniTime are 16bit
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res.hrs = (buf[m] << 8) | ((buf[h] & 0x0f) << 4) | (buf[l] & 0x0f);
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uint32_t Hrs3300::ReadAls() {
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auto m = ReadRegister(static_cast<uint8_t>(Registers::C1dataM));
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auto h = ReadRegister(static_cast<uint8_t>(Registers::C1dataH));
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auto l = ReadRegister(static_cast<uint8_t>(Registers::C1dataL));
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return ((h & 0x3f) << 11) | (m << 3) | (l & 0x07);
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}
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// als
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m = static_cast<uint8_t>(Registers::C1dataM) - baseOffset;
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h = static_cast<uint8_t>(Registers::C1dataH) - baseOffset;
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l = static_cast<uint8_t>(Registers::C1dataL) - baseOffset;
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res.als = ((buf[h] & 0x3f) << 11) | (buf[m] << 3) | (buf[l] & 0x07);
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void Hrs3300::SetGain(uint8_t gain) {
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constexpr uint8_t maxGain = 64U;
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gain = std::min(gain, maxGain);
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uint8_t hgain = 0;
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while ((1 << hgain) < gain) {
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++hgain;
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}
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WriteRegister(static_cast<uint8_t>(Registers::Hgain), hgain << 2);
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}
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void Hrs3300::SetDrive(uint8_t drive) {
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auto en = ReadRegister(static_cast<uint8_t>(Registers::Enable));
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auto pd = ReadRegister(static_cast<uint8_t>(Registers::PDriver));
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en = (en & 0xf7) | ((drive & 2) << 2);
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pd = (pd & 0xbf) | ((drive & 1) << 6);
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WriteRegister(static_cast<uint8_t>(Registers::Enable), en);
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WriteRegister(static_cast<uint8_t>(Registers::PDriver), pd);
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return res;
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}
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void Hrs3300::WriteRegister(uint8_t reg, uint8_t data) {
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@ -21,6 +21,11 @@ namespace Pinetime {
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Hgain = 0x17
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};
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struct PackedHrsAls {
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uint16_t hrs;
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uint16_t als;
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};
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Hrs3300(TwiMaster& twiMaster, uint8_t twiAddress);
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Hrs3300(const Hrs3300&) = delete;
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Hrs3300& operator=(const Hrs3300&) = delete;
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@ -30,10 +35,7 @@ namespace Pinetime {
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void Init();
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void Enable();
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void Disable();
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uint32_t ReadHrs();
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uint32_t ReadAls();
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void SetGain(uint8_t gain);
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void SetDrive(uint8_t drive);
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PackedHrsAls ReadHrsAls();
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private:
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TwiMaster& twiMaster;
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@ -70,7 +70,8 @@ void HeartRateTask::Work() {
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}
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if (measurementStarted) {
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int8_t ambient = ppg.Preprocess(heartRateSensor.ReadHrs(), heartRateSensor.ReadAls());
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auto sensorData = heartRateSensor.ReadHrsAls();
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int8_t ambient = ppg.Preprocess(sensorData.hrs, sensorData.als);
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int bpm = ppg.HeartRate();
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// If ambient light detected or a reset requested (bpm < 0)
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