/
mpu9250.go
767 lines (682 loc) · 23.5 KB
/
mpu9250.go
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package mpu9250
// Approach adapted from the InvenSense DMP 6.1 drivers
// Also referenced https://github.com/brianc118/MPU9250/blob/master/MPU9250.cpp
import (
"errors"
"fmt"
"log"
"math"
"time"
"github.com/kidoman/embd"
_ "github.com/kidoman/embd/host/all" // Empty import needed to initialize embd library.
_ "github.com/kidoman/embd/host/rpi" // Empty import needed to initialize embd library.
"github.com/westphae/goflying/sensors"
)
const (
bufSize = 250 // Size of buffer storing instantaneous sensor values
scaleMag = 9830.0 / 65536
)
/*
MPU9250 represents an InvenSense MPU9250 9DoF chip.
All communication is via channels.
*/
type MPU9250 struct {
sensors.IMUSensor
sensors.IMUCalData
Address byte
i2cbus embd.I2CBus
scaleGyro, scaleAccel float64 // Max sensor reading for value 2**15-1
sampleRate int
enableMag bool
mcal1, mcal2, mcal3 float64 // Hardware magnetometer calibration values, uT
cClose chan bool // Turn off MPU polling
}
/*
NewMPU9250 creates a new MPU9250 object according to the supplied parameters. If there is no MPU9250 available or there
is an error creating the object, an error is returned.
*/
func NewMPU9250(i2cbus *embd.I2CBus, address byte, sensitivityGyro, sensitivityAccel, sampleRate int, enableMag bool, applyHWOffsets bool) (*MPU9250, error) {
var mpu = new(MPU9250)
if err := mpu.IMUCalData.Load(); err != nil {
mpu.IMUCalData.Reset()
}
mpu.sampleRate = sampleRate
mpu.enableMag = enableMag
mpu.i2cbus = *i2cbus
mpu.Address = address
// Initialization of MPU
// Reset device.
if err := mpu.i2cWrite(MPUREG_PWR_MGMT_1, BIT_H_RESET); err != nil {
return nil, errors.New("error resetting MPU9250")
}
// Note: the following is in inv_mpu.c, but doesn't appear to be necessary from the MPU-9250 register map.
// Wake up chip.
time.Sleep(100 * time.Millisecond)
if err := mpu.i2cWrite(MPUREG_PWR_MGMT_1, 0x00); err != nil {
return nil, errors.New("error waking MPU9250")
}
// Note: inv_mpu.c sets some registers here to allocate 1kB to the FIFO buffer and 3kB to the DMP.
// It doesn't seem to be supported in the 1.6 version of the register map and we're not using FIFO anyway,
// so we skip this.
// Don't let FIFO overwrite DMP data
if err := mpu.i2cWrite(MPUREG_ACCEL_CONFIG_2, BIT_FIFO_SIZE_1024|0x8); err != nil {
return nil, errors.New("error setting up MPU9250")
}
// Set Gyro and Accel sensitivities
if err := mpu.SetGyroSensitivity(sensitivityGyro); err != nil {
log.Println(err)
}
if err := mpu.SetAccelSensitivity(sensitivityAccel); err != nil {
log.Println(err)
}
sampRate := byte(1000/mpu.sampleRate - 1)
// Default: Set Gyro LPF to half of sample rate
if err := mpu.SetGyroLPF(sampRate >> 1); err != nil {
return nil, err
}
// Default: Set Accel LPF to half of sample rate
if err := mpu.SetAccelLPF(sampRate >> 1); err != nil {
return nil, err
}
// Set sample rate to chosen
if err := mpu.SetSampleRate(sampRate); err != nil {
return nil, err
}
// Turn off FIFO buffer
if err := mpu.i2cWrite(MPUREG_FIFO_EN, 0x00); err != nil {
return nil, errors.New("MPU9250 Error: couldn't disable FIFO")
}
// Turn off interrupts
if err := mpu.i2cWrite(MPUREG_INT_ENABLE, 0x00); err != nil {
return nil, errors.New("MPU9250 Error: couldn't disable interrupts")
}
// Set up magnetometer
if mpu.enableMag {
if err := mpu.ReadMagCalibration(); err != nil {
return nil, errors.New("error reading calibration from magnetometer")
}
// Set up AK8963 master mode, master clock and ES bit
if err := mpu.i2cWrite(MPUREG_I2C_MST_CTRL, 0x40); err != nil {
return nil, errors.New("error setting up AK8963")
}
// Slave 0 reads from AK8963
if err := mpu.i2cWrite(MPUREG_I2C_SLV0_ADDR, BIT_I2C_READ|AK8963_I2C_ADDR); err != nil {
return nil, errors.New("error setting up AK8963")
}
// Compass reads start at this register
if err := mpu.i2cWrite(MPUREG_I2C_SLV0_REG, AK8963_ST1); err != nil {
return nil, errors.New("error setting up AK8963")
}
// Enable 8-byte reads on slave 0
if err := mpu.i2cWrite(MPUREG_I2C_SLV0_CTRL, BIT_SLAVE_EN|8); err != nil {
return nil, errors.New("error setting up AK8963")
}
// Slave 1 can change AK8963 measurement mode
if err := mpu.i2cWrite(MPUREG_I2C_SLV1_ADDR, AK8963_I2C_ADDR); err != nil {
return nil, errors.New("error setting up AK8963")
}
if err := mpu.i2cWrite(MPUREG_I2C_SLV1_REG, AK8963_CNTL1); err != nil {
return nil, errors.New("error setting up AK8963")
}
// Enable 1-byte reads on slave 1
if err := mpu.i2cWrite(MPUREG_I2C_SLV1_CTRL, BIT_SLAVE_EN|1); err != nil {
return nil, errors.New("error setting up AK8963")
}
// Set slave 1 data
if err := mpu.i2cWrite(MPUREG_I2C_SLV1_DO, AKM_SINGLE_MEASUREMENT); err != nil {
return nil, errors.New("error setting up AK8963")
}
// Triggers slave 0 and 1 actions at each sample
if err := mpu.i2cWrite(MPUREG_I2C_MST_DELAY_CTRL, 0x03); err != nil {
return nil, errors.New("error setting up AK8963")
}
// Set AK8963 sample rate to same as gyro/accel sample rate, up to max
var ak8963Rate byte
if mpu.sampleRate < AK8963_MAX_SAMPLE_RATE {
ak8963Rate = 0
} else {
ak8963Rate = byte(mpu.sampleRate/AK8963_MAX_SAMPLE_RATE - 1)
}
// Not so sure of this one--I2C Slave 4??!
if err := mpu.i2cWrite(MPUREG_I2C_SLV4_CTRL, ak8963Rate); err != nil {
return nil, errors.New("error setting up AK8963")
}
time.Sleep(100 * time.Millisecond) // Make sure mag is ready
}
// Set clock source to PLL
if err := mpu.i2cWrite(MPUREG_PWR_MGMT_1, INV_CLK_PLL); err != nil {
return nil, errors.New("error setting up MPU9250")
}
// Turn off all sensors -- Not sure if necessary, but it's in the InvenSense DMP driver
if err := mpu.i2cWrite(MPUREG_PWR_MGMT_2, 0x63); err != nil {
return nil, errors.New("error setting up MPU9250")
}
time.Sleep(100 * time.Millisecond)
// Turn on all gyro, all accel
if err := mpu.i2cWrite(MPUREG_PWR_MGMT_2, 0x00); err != nil {
return nil, errors.New("error setting up MPU9250")
}
if applyHWOffsets {
if err := mpu.ReadAccelBias(sensitivityAccel); err != nil {
return nil, err
}
if err := mpu.ReadGyroBias(sensitivityGyro); err != nil {
return nil, err
}
}
// Usually we don't want the automatic gyro bias compensation - it pollutes the gyro in a non-inertial frame.
if err := mpu.EnableGyroBiasCal(false); err != nil {
return nil, err
}
go mpu.readSensors()
// Give the IMU time to fully initialize and then clear out any bad values from the averages.
time.Sleep(500 * time.Millisecond) // Make sure it's ready
<-mpu.CAvg // Discard the first readings.
return mpu, nil
}
// readSensors polls the gyro, accelerometer and magnetometer sensors as well as the die temperature.
// Communication is via channels.
func (mpu *MPU9250) readSensors() {
var (
g1, g2, g3, a1, a2, a3, m1, m2, m3, m4, tmp int16 // Current values
avg1, avg2, avg3, ava1, ava2, ava3, avtmp float64 // Accumulators for averages
avm1, avm2, avm3 int32
n, nm float64
gaError, magError error
t0, t, t0m, tm time.Time
magSampleRate int
curdata *sensors.IMUData
)
acRegMap := map[*int16]byte{
&g1: MPUREG_GYRO_XOUT_H, &g2: MPUREG_GYRO_YOUT_H, &g3: MPUREG_GYRO_ZOUT_H,
&a1: MPUREG_ACCEL_XOUT_H, &a2: MPUREG_ACCEL_YOUT_H, &a3: MPUREG_ACCEL_ZOUT_H,
&tmp: MPUREG_TEMP_OUT_H,
}
magRegMap := map[*int16]byte{
&m1: MPUREG_EXT_SENS_DATA_00, &m2: MPUREG_EXT_SENS_DATA_02, &m3: MPUREG_EXT_SENS_DATA_04, &m4: MPUREG_EXT_SENS_DATA_06,
}
if mpu.sampleRate > 100 {
magSampleRate = 100
} else {
magSampleRate = mpu.sampleRate
}
cC := make(chan *sensors.IMUData)
defer close(cC)
mpu.C = cC
cAvg := make(chan *sensors.IMUData)
defer close(cAvg)
mpu.CAvg = cAvg
cBuf := make(chan *sensors.IMUData, bufSize)
defer close(cBuf)
mpu.CBuf = cBuf
mpu.cClose = make(chan bool)
defer close(mpu.cClose)
clock := time.NewTicker(time.Duration(int(1000.0/float32(mpu.sampleRate)+0.5)) * time.Millisecond)
//TODO westphae: use the clock to record actual time instead of a timer
defer clock.Stop()
clockMag := time.NewTicker(time.Duration(int(1000.0/float32(magSampleRate)+0.5)) * time.Millisecond)
t0 = time.Now()
t0m = time.Now()
makeIMUData := func() *sensors.IMUData {
mm1 := float64(m1)*mpu.mcal1 - mpu.M01
mm2 := float64(m2)*mpu.mcal2 - mpu.M02
mm3 := float64(m3)*mpu.mcal3 - mpu.M03
d := sensors.IMUData{
G1: (float64(g1) - mpu.G01) * mpu.scaleGyro,
G2: (float64(g2) - mpu.G02) * mpu.scaleGyro,
G3: (float64(g3) - mpu.G03) * mpu.scaleGyro,
A1: (float64(a1) - mpu.A01) * mpu.scaleAccel,
A2: (float64(a2) - mpu.A02) * mpu.scaleAccel,
A3: (float64(a3) - mpu.A03) * mpu.scaleAccel,
M1: mpu.Ms11*mm1 + mpu.Ms12*mm2 + mpu.Ms13*mm3,
M2: mpu.Ms21*mm1 + mpu.Ms22*mm2 + mpu.Ms23*mm3,
M3: mpu.Ms31*mm1 + mpu.Ms32*mm2 + mpu.Ms33*mm3,
Temp: float64(tmp)/340 + 36.53,
GAError: gaError, MagError: magError,
N: 1, NM: 1,
T: t, TM: tm,
DT: time.Duration(0), DTM: time.Duration(0),
}
if gaError != nil {
d.N = 0
}
if magError != nil {
d.NM = 0
}
return &d
}
makeAvgIMUData := func() *sensors.IMUData {
mm1 := float64(avm1)*mpu.mcal1/nm - mpu.M01
mm2 := float64(avm2)*mpu.mcal2/nm - mpu.M02
mm3 := float64(avm3)*mpu.mcal3/nm - mpu.M03
d := sensors.IMUData{}
if n > 0.5 {
d.G1 = (avg1/n - mpu.G01) * mpu.scaleGyro
d.G2 = (avg2/n - mpu.G02) * mpu.scaleGyro
d.G3 = (avg3/n - mpu.G03) * mpu.scaleGyro
d.A1 = (ava1/n - mpu.A01) * mpu.scaleAccel
d.A2 = (ava2/n - mpu.A02) * mpu.scaleAccel
d.A3 = (ava3/n - mpu.A03) * mpu.scaleAccel
d.Temp = (avtmp/n)/340 + 36.53
d.N = int(n + 0.5)
d.T = t
d.DT = t.Sub(t0)
} else {
d.GAError = errors.New("mpu9250 error: No new accel/gyro values")
}
if nm > 0 {
d.M1 = mpu.Ms11*mm1 + mpu.Ms12*mm2 + mpu.Ms13*mm3
d.M2 = mpu.Ms21*mm1 + mpu.Ms22*mm2 + mpu.Ms23*mm3
d.M3 = mpu.Ms31*mm1 + mpu.Ms32*mm2 + mpu.Ms33*mm3
d.NM = int(nm + 0.5)
d.TM = tm
d.DTM = t.Sub(t0m)
} else {
d.MagError = errors.New("mpu9250 error: no new magnetometer values")
}
return &d
}
for {
select {
case t = <-clock.C: // Read accel/gyro data:
for p, reg := range acRegMap {
*p, gaError = mpu.i2cRead2(reg)
if gaError != nil {
log.Println("mpu9250 warning: error reading gyro/accel")
}
}
curdata = makeIMUData()
// Update accumulated values and increment count of gyro/accel readings
avg1 += float64(g1)
avg2 += float64(g2)
avg3 += float64(g3)
ava1 += float64(a1)
ava2 += float64(a2)
ava3 += float64(a3)
avtmp += float64(tmp)
avm1 += int32(m1)
avm2 += int32(m2)
avm3 += int32(m3)
n++
select {
case cBuf <- curdata: // We update the buffer every time we read a new value.
default: // If buffer is full, remove oldest value and put in newest.
<-cBuf
cBuf <- curdata
}
case tm = <-clockMag.C: // Read magnetometer data:
if mpu.enableMag {
// Set AK8963 to slave0 for reading
if err := mpu.i2cWrite(MPUREG_I2C_SLV0_ADDR, AK8963_I2C_ADDR|READ_FLAG); err != nil {
log.Printf("mpu9250 error: couldn't set AK8963 address for reading: %s", err.Error())
}
//I2C slave 0 register address from where to begin data transfer
if err := mpu.i2cWrite(MPUREG_I2C_SLV0_REG, AK8963_HXL); err != nil {
log.Printf("mpu9250 error: couldn't set AK8963 read register: %s", err.Error())
}
//Tell AK8963 that we will read 7 bytes
if err := mpu.i2cWrite(MPUREG_I2C_SLV0_CTRL, 0x87); err != nil {
log.Printf("mpu9250 error: couldn't communicate with AK8963: %s", err.Error())
}
// Read the actual data
for p, reg := range magRegMap {
*p, magError = mpu.i2cRead2(reg)
if magError != nil {
log.Println("mpu9250 warning: error reading magnetometer")
}
}
// Test validity of magnetometer data
if (byte(m1&0xFF)&AKM_DATA_READY) == 0x00 && (byte(m1&0xFF)&AKM_DATA_OVERRUN) != 0x00 {
log.Println("MPU9250 mag data not ready or overflow")
log.Printf("MPU9250 m1 LSB: %X\n", byte(m1&0xFF))
continue // Don't update the accumulated values
}
if (byte((m4>>8)&0xFF) & AKM_OVERFLOW) != 0x00 {
log.Println("MPU9250 mag data overflow")
log.Printf("MPU9250 m4 MSB: %X\n", byte((m1>>8)&0xFF))
continue // Don't update the accumulated values
}
// Update values and increment count of magnetometer readings
avm1 += int32(m1)
avm2 += int32(m2)
avm3 += int32(m3)
nm++
}
case cC <- curdata: // Send the latest values
case cAvg <- makeAvgIMUData(): // Send the averages
avg1, avg2, avg3 = 0, 0, 0
ava1, ava2, ava3 = 0, 0, 0
avm1, avm2, avm3 = 0, 0, 0
avtmp = 0
n, nm = 0, 0
t0, t0m = t, tm
case <-mpu.cClose: // Stop the goroutine, ease up on the CPU
break
}
}
}
// CloseMPU stops the driver from reading the MPU.
//TODO westphae: need a way to start it going again!
func (mpu *MPU9250) CloseMPU() {
// Nothing to do bitwise for the 9250?
mpu.cClose <- true
}
// SetSampleRate changes the sampling rate of the MPU.
func (mpu *MPU9250) SetSampleRate(rate byte) (err error) {
errWrite := mpu.i2cWrite(MPUREG_SMPLRT_DIV, rate) // Set sample rate to chosen
if errWrite != nil {
err = fmt.Errorf("mpu9250 error: couldn't set sample rate: %s", errWrite.Error())
}
return
}
// SetGyroLPF sets the low pass filter for the gyro.
func (mpu *MPU9250) SetGyroLPF(rate byte) (err error) {
var r byte
switch {
case rate >= 188:
r = BITS_DLPF_CFG_188HZ
case rate >= 98:
r = BITS_DLPF_CFG_98HZ
case rate >= 42:
r = BITS_DLPF_CFG_42HZ
case rate >= 20:
r = BITS_DLPF_CFG_20HZ
case rate >= 10:
r = BITS_DLPF_CFG_10HZ
default:
r = BITS_DLPF_CFG_5HZ
}
errWrite := mpu.i2cWrite(MPUREG_CONFIG, r)
if errWrite != nil {
err = fmt.Errorf("MPU9250 Error: couldn't set Gyro LPF: %s", errWrite.Error())
}
return
}
// SetAccelLPF sets the low pass filter for the accelerometer.
func (mpu *MPU9250) SetAccelLPF(rate byte) (err error) {
var r byte
switch {
case rate >= 218:
r = BITS_DLPF_CFG_188HZ
case rate >= 99:
r = BITS_DLPF_CFG_98HZ
case rate >= 45:
r = BITS_DLPF_CFG_42HZ
case rate >= 21:
r = BITS_DLPF_CFG_20HZ
case rate >= 10:
r = BITS_DLPF_CFG_10HZ
default:
r = BITS_DLPF_CFG_5HZ
}
errWrite := mpu.i2cWrite(MPUREG_ACCEL_CONFIG_2, r)
if errWrite != nil {
err = fmt.Errorf("MPU9250 Error: couldn't set Accel LPF: %s", errWrite.Error())
}
return
}
// EnableGyroBiasCal enables or disables motion bias compensation for the gyro.
// For flying we generally do not want this!
func (mpu *MPU9250) EnableGyroBiasCal(enable bool) error {
enableRegs := []byte{0xb8, 0xaa, 0xb3, 0x8d, 0xb4, 0x98, 0x0d, 0x35, 0x5d}
disableRegs := []byte{0xb8, 0xaa, 0xaa, 0xaa, 0xb0, 0x88, 0xc3, 0xc5, 0xc7}
if enable {
if err := mpu.memWrite(CFG_MOTION_BIAS, &enableRegs); err != nil {
return errors.New("unable to enable motion bias compensation")
}
} else {
if err := mpu.memWrite(CFG_MOTION_BIAS, &disableRegs); err != nil {
return errors.New("unable to disable motion bias compensation")
}
}
return nil
}
// SampleRate returns the current sample rate of the MPU9250, in Hz.
func (mpu *MPU9250) SampleRate() int {
return mpu.sampleRate
}
// MagEnabled returns whether or not the magnetometer is being read.
func (mpu *MPU9250) MagEnabled() bool {
return mpu.enableMag
}
// SetGyroSensitivity sets the gyro sensitivity of the MPU9250; it must be one of the following values:
// 250, 500, 1000, 2000 (all in deg/s).
func (mpu *MPU9250) SetGyroSensitivity(sensitivityGyro int) (err error) {
var sensGyro byte
switch sensitivityGyro {
case 2000:
sensGyro = BITS_FS_2000DPS
mpu.scaleGyro = 2000.0 / float64(math.MaxInt16)
case 1000:
sensGyro = BITS_FS_1000DPS
mpu.scaleGyro = 1000.0 / float64(math.MaxInt16)
case 500:
sensGyro = BITS_FS_500DPS
mpu.scaleGyro = 500.0 / float64(math.MaxInt16)
case 250:
sensGyro = BITS_FS_250DPS
mpu.scaleGyro = 250.0 / float64(math.MaxInt16)
default:
err = fmt.Errorf("MPU9250 Error: %d is not a valid gyro sensitivity", sensitivityGyro)
}
if errWrite := mpu.i2cWrite(MPUREG_GYRO_CONFIG, sensGyro); errWrite != nil {
err = errors.New("MPU9250 Error: couldn't set gyro sensitivity")
}
return
}
// SetAccelSensitivity sets the accelerometer sensitivity of the MPU9250; it must be one of the following values:
// 2, 4, 8, 16, all in G (gravity).
func (mpu *MPU9250) SetAccelSensitivity(sensitivityAccel int) (err error) {
var sensAccel byte
switch sensitivityAccel {
case 16:
sensAccel = BITS_FS_16G
mpu.scaleAccel = 16.0 / float64(math.MaxInt16)
case 8:
sensAccel = BITS_FS_8G
mpu.scaleAccel = 8.0 / float64(math.MaxInt16)
case 4:
sensAccel = BITS_FS_4G
mpu.scaleAccel = 4.0 / float64(math.MaxInt16)
case 2:
sensAccel = BITS_FS_2G
mpu.scaleAccel = 2.0 / float64(math.MaxInt16)
default:
err = fmt.Errorf("MPU9250 Error: %d is not a valid accel sensitivity", sensitivityAccel)
}
if errWrite := mpu.i2cWrite(MPUREG_ACCEL_CONFIG, sensAccel); errWrite != nil {
err = errors.New("MPU9250 Error: couldn't set accel sensitivity")
}
return
}
// ReadAccelBias reads the bias accelerometer value stored on the chip.
// These values are set at the factory.
func (mpu *MPU9250) ReadAccelBias(sensitivityAccel int) error {
a0x, err := mpu.i2cRead2(MPUREG_XA_OFFSET_H)
if err != nil {
return errors.New("MPU9250 Error: ReadAccelBias error reading chip")
}
a0y, err := mpu.i2cRead2(MPUREG_YA_OFFSET_H)
if err != nil {
return errors.New("MPU9250 Error: ReadAccelBias error reading chip")
}
a0z, err := mpu.i2cRead2(MPUREG_ZA_OFFSET_H)
if err != nil {
return errors.New("MPU9250 Error: ReadAccelBias error reading chip")
}
switch sensitivityAccel {
case 16:
mpu.A01 = float64(a0x >> 1)
mpu.A02 = float64(a0y >> 1)
mpu.A03 = float64(a0z >> 1)
case 8:
mpu.A01 = float64(a0x)
mpu.A02 = float64(a0y)
mpu.A03 = float64(a0z)
case 4:
mpu.A01 = float64(a0x << 1)
mpu.A02 = float64(a0y << 1)
mpu.A03 = float64(a0z << 1)
case 2:
mpu.A01 = float64(a0x << 2)
mpu.A02 = float64(a0y << 2)
mpu.A03 = float64(a0z << 2)
default:
return fmt.Errorf("MPU9250 Error: %d is not a valid acceleration sensitivity", sensitivityAccel)
}
return nil
}
// ReadGyroBias reads the bias gyro value stored on the chip.
// These values are set at the factory.
func (mpu *MPU9250) ReadGyroBias(sensitivityGyro int) error {
g0x, err := mpu.i2cRead2(MPUREG_XG_OFFS_USRH)
if err != nil {
return errors.New("MPU9250 Error: ReadGyroBias error reading chip")
}
g0y, err := mpu.i2cRead2(MPUREG_YG_OFFS_USRH)
if err != nil {
return errors.New("MPU9250 Error: ReadGyroBias error reading chip")
}
g0z, err := mpu.i2cRead2(MPUREG_ZG_OFFS_USRH)
if err != nil {
return errors.New("MPU9250 Error: ReadGyroBias error reading chip")
}
switch sensitivityGyro {
case 2000:
mpu.G01 = float64(g0x >> 1)
mpu.G02 = float64(g0y >> 1)
mpu.G03 = float64(g0z >> 1)
case 1000:
mpu.G01 = float64(g0x)
mpu.G02 = float64(g0y)
mpu.G03 = float64(g0z)
case 500:
mpu.G01 = float64(g0x << 1)
mpu.G02 = float64(g0y << 1)
mpu.G03 = float64(g0z << 1)
case 250:
mpu.G01 = float64(g0x << 2)
mpu.G02 = float64(g0y << 2)
mpu.G03 = float64(g0z << 2)
default:
return fmt.Errorf("MPU9250 Error: %d is not a valid gyro sensitivity", sensitivityGyro)
}
return nil
}
// ReadMagCalibration reads the magnetometer bias values stored on the chpi.
// These values are set at the factory.
func (mpu *MPU9250) ReadMagCalibration() error {
// Enable bypass mode
var tmp uint8
var err error
tmp, err = mpu.i2cRead(MPUREG_USER_CTRL)
if err != nil {
return errors.New("ReadMagCalibration error reading chip")
}
if err = mpu.i2cWrite(MPUREG_USER_CTRL, tmp & ^BIT_AUX_IF_EN); err != nil {
return errors.New("ReadMagCalibration error reading chip")
}
time.Sleep(3 * time.Millisecond)
if err = mpu.i2cWrite(MPUREG_INT_PIN_CFG, BIT_BYPASS_EN); err != nil {
return errors.New("ReadMagCalibration error reading chip")
}
// Prepare for getting sensitivity data from AK8963
//Set the I2C slave address of AK8963
if err = mpu.i2cWrite(MPUREG_I2C_SLV0_ADDR, AK8963_I2C_ADDR); err != nil {
return errors.New("ReadMagCalibration error reading chip")
}
// Power down the AK8963
if err = mpu.i2cWrite(MPUREG_I2C_SLV0_CTRL, AK8963_CNTL1); err != nil {
return errors.New("ReadMagCalibration error reading chip")
}
// Power down the AK8963
if err = mpu.i2cWrite(MPUREG_I2C_SLV0_DO, AKM_POWER_DOWN); err != nil {
return errors.New("ReadMagCalibration error reading chip")
}
time.Sleep(time.Millisecond)
// Fuse AK8963 ROM access
if err = mpu.i2cWrite(MPUREG_I2C_SLV0_DO, AK8963_I2CDIS); err != nil {
return errors.New("ReadMagCalibration error reading chip")
}
time.Sleep(time.Millisecond)
// Get sensitivity data from AK8963 fuse ROM
mcal1, err := mpu.i2cRead(AK8963_ASAX)
if err != nil {
return errors.New("ReadMagCalibration error reading chip")
}
mcal2, err := mpu.i2cRead(AK8963_ASAY)
if err != nil {
return errors.New("ReadMagCalibration error reading chip")
}
mcal3, err := mpu.i2cRead(AK8963_ASAZ)
if err != nil {
return errors.New("ReadMagCalibration error reading chip")
}
mpu.mcal1 = float64(int16(mcal1)+128) / 256 * scaleMag
mpu.mcal2 = float64(int16(mcal2)+128) / 256 * scaleMag
mpu.mcal3 = float64(int16(mcal3)+128) / 256 * scaleMag
// Clean up from getting sensitivity data from AK8963
// Fuse AK8963 ROM access
if err = mpu.i2cWrite(MPUREG_I2C_SLV0_DO, AK8963_I2CDIS); err != nil {
return errors.New("ReadMagCalibration error reading chip")
}
time.Sleep(time.Millisecond)
// Disable bypass mode now that we're done getting sensitivity data
tmp, err = mpu.i2cRead(MPUREG_USER_CTRL)
if err != nil {
return errors.New("ReadMagCalibration error reading chip")
}
if err = mpu.i2cWrite(MPUREG_USER_CTRL, tmp|BIT_AUX_IF_EN); err != nil {
return errors.New("ReadMagCalibration error reading chip")
}
time.Sleep(3 * time.Millisecond)
if err = mpu.i2cWrite(MPUREG_INT_PIN_CFG, 0x00); err != nil {
return errors.New("ReadMagCalibration error reading chip")
}
time.Sleep(3 * time.Millisecond)
return nil
}
func (mpu *MPU9250) i2cWrite(register, value byte) (err error) {
if errWrite := mpu.i2cbus.WriteByteToReg(mpu.Address, register, value); errWrite != nil {
err = fmt.Errorf("mpu9250 error writing %X to %X: %s\n",
value, register, errWrite.Error())
} else {
time.Sleep(time.Millisecond)
}
return
}
func (mpu *MPU9250) i2cRead(register byte) (value uint8, err error) {
value, errWrite := mpu.i2cbus.ReadByteFromReg(mpu.Address, register)
if errWrite != nil {
err = fmt.Errorf("i2cRead error: %s", errWrite.Error())
}
return
}
func (mpu *MPU9250) i2cRead2(register byte) (value int16, err error) {
v, errWrite := mpu.i2cbus.ReadWordFromReg(mpu.Address, register)
if errWrite != nil {
err = fmt.Errorf("mpu9250 error reading %x: %s\n", register, errWrite.Error())
} else {
value = int16(v)
}
return
}
func (mpu *MPU9250) memWrite(addr uint16, data *[]byte) error {
var err error
var tmp = make([]byte, 2)
tmp[0] = byte(addr >> 8)
tmp[1] = byte(addr & 0xFF)
// Check memory bank boundaries
if tmp[1]+byte(len(*data)) > MPU_BANK_SIZE {
return errors.New("bad address: writing outside of memory bank boundaries")
}
err = mpu.i2cbus.WriteToReg(mpu.Address, MPUREG_BANK_SEL, tmp)
if err != nil {
return fmt.Errorf("mpu9250 error selecting memory bank: %s\n", err.Error())
}
err = mpu.i2cbus.WriteToReg(mpu.Address, MPUREG_MEM_R_W, *data)
if err != nil {
return fmt.Errorf("mpu9250 error writing to the memory bank: %s\n", err.Error())
}
return nil
}