mirror of
https://github.com/kidoman/embd
synced 2024-11-01 07:48:43 +01:00
315 lines
6.6 KiB
Go
315 lines
6.6 KiB
Go
// Package tmp006 allows interfacing with the TMP006 thermopile.
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package tmp006
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import (
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"errors"
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"fmt"
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"math"
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"sync"
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"time"
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"github.com/golang/glog"
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"github.com/kidoman/embd"
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)
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const (
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b0 = -0.0000294
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b1 = -0.00000057
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b2 = 0.00000000463
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c2 = 13.4
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tref = 298.15
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a2 = -0.00001678
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a1 = 0.00175
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s0 = 6.4
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vObjReg = 0x00
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tempAmbReg = 0x01
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configReg = 0x02
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manIdReg = 0xFE
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manId = 0x5449
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devIdReg = 0xFF
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devId = 0x0067
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reset = 0x8000
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modeOn = 0x7000
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drdyEn = 0x0100
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configRegDefault = modeOn | drdyEn
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)
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type SampleRate struct {
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enabler uint16
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samples int
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timeRequired float64
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}
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var (
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SR1 = &SampleRate{0x0000, 1, 0.25} // 1 sample, 0.25 second between measurements.
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SR2 = &SampleRate{0x0200, 2, 0.5} // 2 samples, 0.5 second between measurements.
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SR4 = &SampleRate{0x0400, 4, 1} // 4 samples, 1 second between measurements.
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SR8 = &SampleRate{0x0600, 8, 2} // 8 samples, 2 seconds between measurements.
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SR16 = &SampleRate{0x0800, 16, 4} // 16 samples, 4 seconds between measurements.
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)
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// TMP006 represents a TMP006 thermopile sensor.
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type TMP006 struct {
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// Bus to communicate over.
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Bus embd.I2CBus
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// Addr of the sensor.
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Addr byte
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// SampleRate specifies the sampling rate for the sensor.
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SampleRate *SampleRate
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initialized bool
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mu sync.RWMutex
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rawDieTemps chan float64
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objTemps chan float64
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closing chan chan struct{}
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}
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// New creates a new TMP006 sensor.
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func New(bus embd.I2CBus, addr byte) *TMP006 {
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return &TMP006{
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Bus: bus,
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Addr: addr,
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}
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}
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func (d *TMP006) validate() error {
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if d.Bus == nil {
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return errors.New("tmp006: bus is nil")
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}
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if d.Addr == 0x00 {
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return fmt.Errorf("tmp006: %#x is not a valid address", d.Addr)
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}
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return nil
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}
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// Close puts the device into low power mode.
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func (d *TMP006) Close() error {
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if err := d.setup(); err != nil {
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return err
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}
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if d.closing != nil {
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waitc := make(chan struct{})
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d.closing <- waitc
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<-waitc
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}
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glog.V(1).Infof("tmp006: resetting")
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if err := d.Bus.WriteWordToReg(d.Addr, configReg, reset); err != nil {
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return err
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}
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return nil
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}
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// Present checks if the device is present at the given address.
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func (d *TMP006) Present() (bool, error) {
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if err := d.validate(); err != nil {
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return false, err
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}
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mid, err := d.Bus.ReadWordFromReg(d.Addr, manIdReg)
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if err != nil {
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return false, err
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}
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glog.V(1).Infof("tmp006: got manufacturer id %#04x", mid)
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if mid != manId {
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return false, fmt.Errorf("tmp006: not found at %#02x, manufacturer id mismatch", d.Addr)
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}
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did, err := d.Bus.ReadWordFromReg(d.Addr, devIdReg)
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if err != nil {
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return false, err
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}
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glog.V(1).Infof("tmp006: got device id %#04x", did)
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if did != devId {
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return false, fmt.Errorf("tmp006: not found at %#02x, device id mismatch", d.Addr)
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}
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return true, nil
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}
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func (d *TMP006) setup() error {
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d.mu.RLock()
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if d.initialized {
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d.mu.RUnlock()
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return nil
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}
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d.mu.RUnlock()
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d.mu.Lock()
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defer d.mu.Unlock()
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if err := d.validate(); err != nil {
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return err
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}
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if d.SampleRate == nil {
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glog.V(1).Infof("tmp006: sample rate = nil, using SR16")
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d.SampleRate = SR16
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}
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glog.V(1).Infof("tmp006: configuring with %#04x", configRegDefault|d.SampleRate.enabler)
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if err := d.Bus.WriteWordToReg(d.Addr, configReg, configRegDefault|d.SampleRate.enabler); err != nil {
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return err
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}
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d.initialized = true
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return nil
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}
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func (d *TMP006) measureRawDieTemp() (float64, error) {
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if err := d.setup(); err != nil {
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return 0, err
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}
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raw, err := d.Bus.ReadWordFromReg(d.Addr, tempAmbReg)
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if err != nil {
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return 0, err
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}
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raw >>= 2
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glog.V(2).Infof("tmp006: raw die temp %#04x", raw)
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temp := float64(int16(raw)) * 0.03125
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return temp, nil
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}
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func (d *TMP006) measureRawVoltage() (int16, error) {
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if err := d.setup(); err != nil {
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return 0, err
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}
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vlt, err := d.Bus.ReadWordFromReg(d.Addr, vObjReg)
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if err != nil {
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return 0, err
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}
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volt := int16(vlt)
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glog.V(2).Infof("tmp006: raw voltage %#04x", volt)
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return volt, nil
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}
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func (d *TMP006) measureObjTemp() (float64, error) {
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if err := d.setup(); err != nil {
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return 0, err
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}
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tDie, err := d.measureRawDieTemp()
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if err != nil {
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return 0, err
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}
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glog.V(2).Infof("tmp006: tdie = %.2f C", tDie)
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tDie += 273.15 // Convert to K
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vo, err := d.measureRawVoltage()
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if err != nil {
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return 0, err
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}
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vObj := float64(vo)
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vObj *= 156.25 // 156.25 nV per LSB
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vObj /= 1000 // nV -> uV
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glog.V(2).Infof("tmp006: vObj = %.5f uV", vObj)
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vObj /= 1000 // uV -> mV
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vObj /= 1000 // mV -> V
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tdie_tref := tDie - tref
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s := 1 + a1*tdie_tref + a2*tdie_tref*tdie_tref
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s *= s0
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s /= 10000000
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s /= 10000000
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Vos := b0 + b1*tdie_tref + b2*tdie_tref*tdie_tref
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fVobj := (vObj - Vos) + c2*(vObj-Vos)*(vObj-Vos)
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temp := math.Sqrt(math.Sqrt(tDie*tDie*tDie*tDie + fVobj/s))
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temp -= 273.15
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return temp, nil
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}
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// RawDieTemp returns the current raw die temp reading.
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func (d *TMP006) RawDieTemp() (float64, error) {
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select {
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case temp := <-d.rawDieTemps:
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return temp, nil
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default:
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return d.measureRawDieTemp()
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}
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}
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// RawDieTemps returns a channel to get future raw die temps from.
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func (d *TMP006) RawDieTemps() <-chan float64 {
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return d.rawDieTemps
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}
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// ObjTemp returns the current obj temp reading.
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func (d *TMP006) ObjTemp() (float64, error) {
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select {
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case temp := <-d.objTemps:
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return temp, nil
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default:
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return d.measureObjTemp()
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}
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}
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// ObjTemps returns a channel to fetch obj temps from.
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func (d *TMP006) ObjTemps() <-chan float64 {
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return d.objTemps
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}
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// Start starts the data acquisition loop.
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func (d *TMP006) Start() error {
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if err := d.setup(); err != nil {
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return err
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}
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d.rawDieTemps = make(chan float64)
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d.objTemps = make(chan float64)
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go func() {
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var rawDieTemp, objTemp float64
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var rdtAvlb, otAvlb bool
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var err error
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var timer <-chan time.Time
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resetTimer := func() {
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timer = time.After(time.Duration(d.SampleRate.timeRequired*1000) * time.Millisecond)
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}
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resetTimer()
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for {
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var rawDieTemps, objTemps chan float64
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if rdtAvlb {
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rawDieTemps = d.rawDieTemps
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}
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if otAvlb {
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objTemps = d.objTemps
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}
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select {
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case <-timer:
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var rdt float64
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if rdt, err = d.measureRawDieTemp(); err != nil {
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glog.Errorf("tmp006: %v", err)
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} else {
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rawDieTemp = rdt
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rdtAvlb = true
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}
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var ot float64
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if ot, err = d.measureObjTemp(); err != nil {
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glog.Errorf("tmp006: %v", err)
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} else {
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objTemp = ot
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otAvlb = true
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}
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resetTimer()
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case rawDieTemps <- rawDieTemp:
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rdtAvlb = false
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case objTemps <- objTemp:
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otAvlb = false
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case waitc := <-d.closing:
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waitc <- struct{}{}
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close(d.rawDieTemps)
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close(d.objTemps)
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return
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}
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}
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}()
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return nil
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}
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