'''

Module for the MPY6050 6DOF IMU.

By default interrupts are disabled while reading or writing to the device. This

prevents occasional bus lockups in the presence of pin interrupts, at the cost

of disabling interrupts for about 250uS.

'''

mpu_addr = 0x68 # address of MPU6050

_I2Cerror = "I2C communication failure"

def __init__(self, side=1, disable_interrupts=False):

# create i2c object

self._timeout = 10

self.disable_interrupts = False

self._mpu_i2c = pyb.I2C(side, pyb.I2C.MASTER)

self.chip_id = int(unp('>h', self._read(1, 0x75, self.mpu_addr))[0])

# now apply user setting for interrupts

self.disable_interrupts = disable_interrupts

# wake it up

self.wake()

self.accel_range(1)

self._ar = self.accel_range()

self.gyro_range(0)

self._gr = self.gyro_range()

# read from device

def _read(self, count, memaddr, devaddr):

'''

Perform a memory read. Caller should trap OSError. Possible values of

error args[0]: errorno.ETIMEDOUT errno.EBUSY or errno.EIO

'''

irq_state = True

if self.disable_interrupts:

irq_state = pyb.disable_irq()

result = self._mpu_i2c.mem_read(count,

devaddr,

memaddr,

timeout=self._timeout)

pyb.enable_irq(irq_state)

return result

# write to device

def _write(self, data, memaddr, devaddr):

'''

Perform a memory write. Caller should trap OSError.

'''

irq_state = True

if self.disable_interrupts:

irq_state = pyb.disable_irq()

result = self._mpu_i2c.mem_write(data,

devaddr,

memaddr,

timeout=self._timeout)

pyb.enable_irq(irq_state)

return result

# wake

def wake(self):

'''

Wakes the device.

'''

try:

self._write(0x01, 0x6B, self.mpu_addr)

except OSError:

print(MPU6050._I2Cerror)

return 'awake'

# mode

def sleep(self):

'''

Sets the device to sleep mode.

'''

try:

self._write(0x40, 0x6B, self.mpu_addr)

except OSError:

print(MPU6050._I2Cerror)

return 'asleep'

# sample rate

def sample_rate(self, rate=None):

'''

Returns the sample rate or sets it to the passed arg in Hz. Note that

not all sample rates are possible. Check the return value to see which

rate was actually set.

'''

gyro_rate = 8000 # Hz

# set rate

try:

if rate is not None:

rate_div = int( gyro_rate/rate - 1 )

if rate_div > 255:

rate_div = 255

self._write(rate_div, 0x19, self.mpu_addr)

# get rate

rate = gyro_rate/(unp('<H', self._read(1, 0x19, self.mpu_addr))[0]+1)

except OSError:

rate = None

return rate

# accelerometer range

def accel_range(self, accel_range=None):

'''

Returns the accelerometer range or sets it to the passed arg.

Pass: 0 1 2 3

for range +/-: 2 4 8 16 g

'''

# set range

try:

if accel_range is None:

pass

else:

ar = (0x00, 0x08, 0x10, 0x18)

try:

self._write(ar[accel_range], 0x1C, self.mpu_addr)

except IndexError:

print('accel_range can only be 0, 1, 2 or 3')

# get range

ari = int(unp('<H', self._read(1, 0x1C, self.mpu_addr))[0]/8)

except OSError:

ari = None

if ari is not None:

self._ar = ari

return ari

# gyroscope range

def gyro_range(self, gyro_range=None):

'''

Returns the gyroscope range or sets it to the passed arg.

Pass: 0 1 2 3

for range +/-: 250 500 1000 2000 degrees/second

'''

# set range

try:

if gyro_range is None:

pass

else:

gr = (0x00, 0x08, 0x10, 0x18)

try:

self._write(gr[gyro_range], 0x1B, self.mpu_addr)

except IndexError:

print('gyro_range can only be 0, 1, 2 or 3')

# get range

gri = int(unp('<H', self._read(1, 0x1B, self.mpu_addr))[0]/8)

except OSError:

gri = None

if gri is not None:

self._gr = gri

return gri

# get raw acceleration

def get_accel_raw(self):

'''

Returns the accelerations on xyz in bytes.

'''

try:

axyz = self._read(6, 0x3B, self.mpu_addr)

except OSError:

axyz = b'\x00\x00\x00\x00\x00\x00'

return axyz

# get acceleration

def get_acc(self, xyz=None):

'''

Returns the accelerations on axis passed in arg. Pass xyz or every

subset of this string. None defaults to xyz.

'''

if xyz is None:

xyz = 'xyz'

scale = (16384, 8192, 4096, 2048)

raw = self.get_accel_raw()

axyz = {'x': unp('>h', raw[0:2])[0]/scale[self._ar],

'y': unp('>h', raw[2:4])[0]/scale[self._ar],

'z': unp('>h', raw[4:6])[0]/scale[self._ar]}

aout = []

for char in xyz:

aout.append(axyz[char])

return aout

# get pitch

def pitch(self):

'''

Returns pitch angle in degrees based on x and z accelerations.

'''

scale = (16384, 8192, 4096, 2048)

raw = self.get_accel_raw()

x = unp('>h', raw[0:2])[0]/scale[self._ar]

z = unp('>h', raw[4:6])[0]/scale[self._ar]

pitch = degrees(pi+atan2(-x,-z))

if (pitch>=180) and (pitch<=360):

pitch-=360

return -pitch

# get roll

def roll(self):

'''

Returns roll angle in degrees based on y and z accelerations.

'''

scale = (16384, 8192, 4096, 2048)

raw = self.get_accel_raw()

y = unp('>h', raw[2:4])[0]/scale[self._ar]

z = unp('>h', raw[4:6])[0]/scale[self._ar]

roll = degress(pi+atan2(-y,-z))

if (roll>=180) and (roll<=360):

roll-=360

return -roll

# get raw gyro

def get_gyro_raw(self):

'''

Returns the turn rate on xyz in bytes.

'''

try:

gxyz = self._read(6, 0x43, self.mpu_addr)

except OSError:

gxyz = b'\x00\x00\x00\x00\x00\x00'

return gxyz

# get gyro

def get_gyro(self, xyz=None, use_radians=False):

'''

Returns the turn rate on axis passed in arg in deg/s or rad/s,

defaulting to degrees. Pass xyz or every

subset of this string. None defaults to xyz.

'''

if xyz is None:

xyz = 'xyz'

if use_radians:

scale = (7150, 3755, 1877.5, 938.75)

else:

scale = (131.0, 65.5, 32.8, 16.4)

raw = self.get_gyro_raw()

gxyz = {'x': unp('>h', raw[0:2])[0]/scale[self._gr],

'y': unp('>h', raw[2:4])[0]/scale[self._gr],

'z': unp('>h', raw[4:6])[0]/scale[self._gr]}

gout = []

for char in xyz:

gout.append(gxyz[char])

return gout

# get gyro pitch - y - axis in degrees

def get_gy(self):

scale = (131.0, 65.5, 32.8, 16.4)

raw = self.get_gyro_raw()

gy = unp('>h', raw[2:4])[0]/scale[self._gr]