mirror of
https://github.com/kidoman/embd
synced 2024-11-01 07:48:43 +01:00
394 lines
8.0 KiB
Go
394 lines
8.0 KiB
Go
// Package bmp085 allows interfacing with Bosch BMP085 barometric pressure sensor. This sensor
|
|
// has the ability to provided compensated temperature and pressure readings.
|
|
package bmp085
|
|
|
|
import (
|
|
"math"
|
|
"sync"
|
|
"time"
|
|
|
|
"github.com/golang/glog"
|
|
"github.com/kidoman/embd"
|
|
)
|
|
|
|
const (
|
|
address = 0x77
|
|
|
|
calAc1 = 0xAA
|
|
calAc2 = 0xAC
|
|
calAc3 = 0xAE
|
|
calAc4 = 0xB0
|
|
calAc5 = 0xB2
|
|
calAc6 = 0xB4
|
|
calB1 = 0xB6
|
|
calB2 = 0xB8
|
|
calMB = 0xBA
|
|
calMC = 0xBC
|
|
calMD = 0xBE
|
|
control = 0xF4
|
|
tempData = 0xF6
|
|
pressureData = 0xF6
|
|
readTempCmd = 0x2E
|
|
readPressureCmd = 0x34
|
|
|
|
tempReadDelay = 5 * time.Millisecond
|
|
|
|
p0 = 101325
|
|
|
|
pollDelay = 250
|
|
)
|
|
|
|
// BMP085 represents a Bosch BMP085 barometric sensor.
|
|
type BMP085 struct {
|
|
Bus embd.I2CBus
|
|
Poll int
|
|
|
|
oss uint
|
|
|
|
ac1, ac2, ac3 int16
|
|
ac4, ac5, ac6 uint16
|
|
b1, b2, mb, mc, md int16
|
|
b5 int32
|
|
calibrated bool
|
|
cmu sync.RWMutex
|
|
|
|
temps chan uint16
|
|
pressures chan int32
|
|
altitudes chan float64
|
|
quit chan struct{}
|
|
}
|
|
|
|
// New returns a handle to a BMP085 sensor.
|
|
func New(bus embd.I2CBus) *BMP085 {
|
|
return &BMP085{Bus: bus, Poll: pollDelay}
|
|
}
|
|
|
|
func (d *BMP085) calibrate() error {
|
|
d.cmu.RLock()
|
|
if d.calibrated {
|
|
d.cmu.RUnlock()
|
|
return nil
|
|
}
|
|
d.cmu.RUnlock()
|
|
|
|
d.cmu.Lock()
|
|
defer d.cmu.Unlock()
|
|
|
|
readInt16 := func(reg byte) (int16, error) {
|
|
v, err := d.Bus.ReadWordFromReg(address, reg)
|
|
if err != nil {
|
|
return 0, err
|
|
}
|
|
return int16(v), nil
|
|
}
|
|
|
|
readUInt16 := func(reg byte) (uint16, error) {
|
|
v, err := d.Bus.ReadWordFromReg(address, reg)
|
|
if err != nil {
|
|
return 0, err
|
|
}
|
|
return uint16(v), nil
|
|
}
|
|
|
|
var err error
|
|
d.ac1, err = readInt16(calAc1)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
d.ac2, err = readInt16(calAc2)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
d.ac3, err = readInt16(calAc3)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
d.ac4, err = readUInt16(calAc4)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
d.ac5, err = readUInt16(calAc5)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
d.ac6, err = readUInt16(calAc6)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
d.b1, err = readInt16(calB1)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
d.b2, err = readInt16(calB2)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
d.mb, err = readInt16(calMB)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
d.mc, err = readInt16(calMC)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
d.md, err = readInt16(calMD)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
d.calibrated = true
|
|
|
|
if glog.V(1) {
|
|
glog.Info("bmp085: calibration data retrieved")
|
|
glog.Infof("bmp085: param AC1 = %v", d.ac1)
|
|
glog.Infof("bmp085: param AC2 = %v", d.ac2)
|
|
glog.Infof("bmp085: param AC3 = %v", d.ac3)
|
|
glog.Infof("bmp085: param AC4 = %v", d.ac4)
|
|
glog.Infof("bmp085: param AC5 = %v", d.ac5)
|
|
glog.Infof("bmp085: param AC6 = %v", d.ac6)
|
|
glog.Infof("bmp085: param B1 = %v", d.b1)
|
|
glog.Infof("bmp085: param B2 = %v", d.b2)
|
|
glog.Infof("bmp085: param MB = %v", d.mb)
|
|
glog.Infof("bmp085: param MC = %v", d.mc)
|
|
glog.Infof("bmp085: param MD = %v", d.md)
|
|
}
|
|
|
|
return nil
|
|
}
|
|
|
|
func (d *BMP085) readUncompensatedTemp() (uint16, error) {
|
|
if err := d.Bus.WriteByteToReg(address, control, readTempCmd); err != nil {
|
|
return 0, err
|
|
}
|
|
time.Sleep(tempReadDelay)
|
|
temp, err := d.Bus.ReadWordFromReg(address, tempData)
|
|
if err != nil {
|
|
return 0, err
|
|
}
|
|
return temp, nil
|
|
}
|
|
|
|
func (d *BMP085) calcTemp(utemp uint16) uint16 {
|
|
x1 := ((int(utemp) - int(d.ac6)) * int(d.ac5)) >> 15
|
|
x2 := (int(d.mc) << 11) / (x1 + int(d.md))
|
|
|
|
d.cmu.Lock()
|
|
d.b5 = int32(x1 + x2)
|
|
d.cmu.Unlock()
|
|
|
|
return uint16((d.b5 + 8) >> 4)
|
|
}
|
|
|
|
func (d *BMP085) measureTemp() (uint16, error) {
|
|
if err := d.calibrate(); err != nil {
|
|
return 0, err
|
|
}
|
|
|
|
utemp, err := d.readUncompensatedTemp()
|
|
if err != nil {
|
|
return 0, err
|
|
}
|
|
glog.V(1).Infof("bcm085: uncompensated temp: %v", utemp)
|
|
temp := d.calcTemp(utemp)
|
|
glog.V(1).Infof("bcm085: compensated temp %v", temp)
|
|
return temp, nil
|
|
}
|
|
|
|
// Temperature returns the current temperature reading.
|
|
func (d *BMP085) Temperature() (float64, error) {
|
|
select {
|
|
case t := <-d.temps:
|
|
temp := float64(t) / 10
|
|
return temp, nil
|
|
default:
|
|
glog.V(1).Infof("bcm085: no temps available... measuring")
|
|
t, err := d.measureTemp()
|
|
if err != nil {
|
|
return 0, err
|
|
}
|
|
temp := float64(t) / 10
|
|
return temp, nil
|
|
}
|
|
}
|
|
|
|
func (d *BMP085) readUncompensatedPressure() (uint32, error) {
|
|
if err := d.Bus.WriteByteToReg(address, control, byte(readPressureCmd+(d.oss<<6))); err != nil {
|
|
return 0, err
|
|
}
|
|
time.Sleep(time.Duration(2+(3<<d.oss)) * time.Millisecond)
|
|
|
|
data := make([]byte, 3)
|
|
if err := d.Bus.ReadFromReg(address, pressureData, data); err != nil {
|
|
return 0, err
|
|
}
|
|
|
|
pressure := ((uint32(data[0]) << 16) | (uint32(data[1]) << 8) | uint32(data[2])) >> (8 - d.oss)
|
|
|
|
return pressure, nil
|
|
}
|
|
|
|
func (d *BMP085) calcPressure(upressure uint32) int32 {
|
|
var x1, x2, x3 int32
|
|
|
|
l := func(s string, v interface{}) {
|
|
glog.V(1).Infof("bcm085: %v = %v", s, v)
|
|
}
|
|
|
|
b6 := d.b5 - 4000
|
|
l("b6", b6)
|
|
|
|
// Calculate b3
|
|
x1 = (int32(d.b2) * int32(b6*b6) >> 12) >> 11
|
|
x2 = (int32(d.ac2) * b6) >> 11
|
|
x3 = x1 + x2
|
|
b3 := (((int32(d.ac1)*4 + x3) << d.oss) + 2) >> 2
|
|
|
|
l("x1", x1)
|
|
l("x2", x2)
|
|
l("x3", x3)
|
|
l("b3", b3)
|
|
|
|
// Calculate b4
|
|
x1 = (int32(d.ac3) * b6) >> 13
|
|
x2 = (int32(d.b1) * ((b6 * b6) >> 12)) >> 16
|
|
x3 = ((x1 + x2) + 2) >> 2
|
|
b4 := (uint32(d.ac4) * uint32(x3+32768)) >> 15
|
|
|
|
l("x1", x1)
|
|
l("x2", x2)
|
|
l("x3", x3)
|
|
l("b4", b4)
|
|
|
|
var p int32
|
|
b7 := (uint32(upressure-uint32(b3)) * (50000 >> d.oss))
|
|
if b7 < 0x80000000 {
|
|
p = int32((b7 << 1) / b4)
|
|
} else {
|
|
p = int32((b7 / b4) << 1)
|
|
}
|
|
l("b7", b7)
|
|
l("p", p)
|
|
|
|
x1 = (p >> 8) * (p >> 8)
|
|
x1 = (x1 * 3038) >> 16
|
|
x2 = (-7357 * p) >> 16
|
|
p += (x1 + x2 + 3791) >> 4
|
|
|
|
l("x1", x1)
|
|
l("x2", x2)
|
|
l("x3", x3)
|
|
l("p", p)
|
|
|
|
return p
|
|
}
|
|
|
|
func (d *BMP085) calcAltitude(pressure int32) float64 {
|
|
return 44330 * (1 - math.Pow(float64(pressure)/p0, 0.190295))
|
|
}
|
|
|
|
func (d *BMP085) measurePressureAndAltitude() (int32, float64, error) {
|
|
if err := d.calibrate(); err != nil {
|
|
return 0, 0, err
|
|
}
|
|
|
|
upressure, err := d.readUncompensatedPressure()
|
|
if err != nil {
|
|
return 0, 0, err
|
|
}
|
|
glog.V(1).Infof("bcm085: uncompensated pressure: %v", upressure)
|
|
pressure := d.calcPressure(upressure)
|
|
glog.V(1).Infof("bcm085: compensated pressure %v", pressure)
|
|
altitude := d.calcAltitude(pressure)
|
|
glog.V(1).Infof("bcm085: calculated altitude %v", altitude)
|
|
return pressure, altitude, nil
|
|
}
|
|
|
|
// Pressure returns the current pressure reading.
|
|
func (d *BMP085) Pressure() (int, error) {
|
|
if err := d.calibrate(); err != nil {
|
|
return 0, err
|
|
}
|
|
|
|
select {
|
|
case p := <-d.pressures:
|
|
return int(p), nil
|
|
default:
|
|
glog.V(1).Infof("bcm085: no pressures available... measuring")
|
|
p, _, err := d.measurePressureAndAltitude()
|
|
if err != nil {
|
|
return 0, err
|
|
}
|
|
return int(p), nil
|
|
}
|
|
}
|
|
|
|
// Altitude returns the current altitude reading.
|
|
func (d *BMP085) Altitude() (float64, error) {
|
|
if err := d.calibrate(); err != nil {
|
|
return 0, err
|
|
}
|
|
|
|
select {
|
|
case altitude := <-d.altitudes:
|
|
return altitude, nil
|
|
default:
|
|
glog.V(1).Info("bcm085: no altitudes available... measuring")
|
|
_, altitude, err := d.measurePressureAndAltitude()
|
|
if err != nil {
|
|
return 0, err
|
|
}
|
|
return altitude, nil
|
|
}
|
|
}
|
|
|
|
// Run starts the sensor data acquisition loop.
|
|
func (d *BMP085) Run() {
|
|
go func() {
|
|
d.quit = make(chan struct{})
|
|
timer := time.Tick(time.Duration(d.Poll) * time.Millisecond)
|
|
|
|
var temp uint16
|
|
var pressure int32
|
|
var altitude float64
|
|
|
|
for {
|
|
select {
|
|
case <-timer:
|
|
t, err := d.measureTemp()
|
|
if err == nil {
|
|
temp = t
|
|
}
|
|
if err == nil && d.temps == nil {
|
|
d.temps = make(chan uint16)
|
|
}
|
|
p, a, err := d.measurePressureAndAltitude()
|
|
if err == nil {
|
|
pressure = p
|
|
altitude = a
|
|
}
|
|
if err == nil && d.pressures == nil && d.altitudes == nil {
|
|
d.pressures = make(chan int32)
|
|
d.altitudes = make(chan float64)
|
|
}
|
|
case d.temps <- temp:
|
|
case d.pressures <- pressure:
|
|
case d.altitudes <- altitude:
|
|
case <-d.quit:
|
|
d.temps = nil
|
|
d.pressures = nil
|
|
d.altitudes = nil
|
|
return
|
|
}
|
|
}
|
|
}()
|
|
|
|
return
|
|
}
|
|
|
|
// Close.
|
|
func (d *BMP085) Close() {
|
|
if d.quit != nil {
|
|
d.quit <- struct{}{}
|
|
}
|
|
}
|