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mpu6050.py
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mpu6050.py
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import collections
import time
from ustruct import unpack
import constants as C
DEFAULT_SAMPLE_RATE = 0x20
ACCEL_RANGE = [2, 4, 8, 16]
GYRO_RANGE = [250, 500, 1000, 2000]
class SensorReadings(
collections.namedtuple(
"SensorReadings", ["AccX", "AccY", "AccZ", "Temp", "GyroX", "GyroY", "GyroZ"]
)
):
pass
class MPU(object):
stable_reading_timeout = 10
max_gyro_variance = 5
def __init__(self, i2c, rate=None, address=None):
self.rate = rate if rate is not None else DEFAULT_SAMPLE_RATE
self.address = address if address else C.MPU6050_DEFAULT_ADDRESS
self.i2c = i2c
self.buffer = bytearray(16)
self.bytebuf = memoryview(self.buffer[0:1])
self.wordbuf = memoryview(self.buffer[0:2])
self.sensors = bytearray(14)
self.init_device()
def write_byte(self, reg, val):
self.bytebuf[0] = val
self.i2c.writeto_mem(self.address, reg, self.bytebuf)
def read_byte(self, reg):
self.i2c.readfrom_mem_into(self.address, reg, self.bytebuf)
return self.bytebuf[0]
def set_bitfield(self, reg, pos, length, val):
old = self.read_byte(reg)
shift = pos - length + 1
mask = (2 ** length - 1) << shift
new = (old & ~mask) | (val << shift)
self.write_byte(reg, new)
def read_word(self, reg):
self.i2c.readfrom_mem_into(self.address, reg, self.wordbuf)
return unpack(">H", self.wordbuf)[0]
def read_word2(self, reg):
self.i2c.readfrom_mem_into(self.address, reg, self.wordbuf)
return unpack(">h", self.wordbuf)[0]
def identify(self):
val = self.read_byte(C.MPU6050_RA_WHO_AM_I)
if val != C.MPU6050_ADDRESS_AD0_LOW:
raise OSError("No mpu6050 at address {}".format(self.address))
def reset(self):
self.write_byte(
C.MPU6050_RA_PWR_MGMT_1, ((1 << C.MPU6050_PWR1_DEVICE_RESET_BIT))
)
time.sleep_ms(100) # type: ignore[attr-defined]
self.write_byte(
C.MPU6050_RA_SIGNAL_PATH_RESET,
(
(1 << C.MPU6050_PATHRESET_GYRO_RESET_BIT)
| (1 << C.MPU6050_PATHRESET_ACCEL_RESET_BIT)
| (1 << C.MPU6050_PATHRESET_TEMP_RESET_BIT)
),
)
time.sleep_ms(100) # type: ignore[attr-defined]
def init_device(self):
self.identify()
# disable sleep mode and select clock source
self.write_byte(C.MPU6050_RA_PWR_MGMT_1, C.MPU6050_CLOCK_PLL_XGYRO)
# enable all sensors
self.write_byte(C.MPU6050_RA_PWR_MGMT_2, 0)
# set sampling rate
self.write_byte(C.MPU6050_RA_SMPLRT_DIV, self.rate)
# enable dlpf
self.write_byte(C.MPU6050_RA_CONFIG, 1)
# explicitly set accel/gyro range
self.set_accel_range(C.MPU6050_ACCEL_FS_2)
self.set_gyro_range(C.MPU6050_GYRO_FS_250)
def set_gyro_range(self, fsr):
self.gyro_range = GYRO_RANGE[fsr]
self.set_bitfield(
C.MPU6050_RA_GYRO_CONFIG,
C.MPU6050_GCONFIG_FS_SEL_BIT,
C.MPU6050_GCONFIG_FS_SEL_LENGTH,
fsr,
)
def set_accel_range(self, fsr):
self.accel_range = ACCEL_RANGE[fsr]
self.set_bitfield(
C.MPU6050_RA_ACCEL_CONFIG,
C.MPU6050_ACONFIG_AFS_SEL_BIT,
C.MPU6050_ACONFIG_AFS_SEL_LENGTH,
fsr,
)
def read_sensors(self):
self.i2c.readfrom_mem_into(
self.address, C.MPU6050_RA_ACCEL_XOUT_H, self.sensors
)
data = unpack(">hhhhhhh", self.sensors)
return SensorReadings(*data)
def read_sensors_scaled(self):
data = list(self.read_sensors())
data[0:3] = [x / (65536 // self.accel_range // 2) for x in data[0:3]]
data[4:7] = [x / (65536 // self.gyro_range // 2) for x in data[4:7]]
return SensorReadings(*data)
def set_dhpf_mode(self, bandwidth):
self.set_bitfield(
C.MPU6050_RA_ACCEL_CONFIG,
C.MPU6050_ACONFIG_ACCEL_HPF_BIT,
C.MPU6050_ACONFIG_ACCEL_HPF_LENGTH,
bandwidth,
)
# 0 Reset
# 1 On @ 5 Hz
# 2 On @ 2.5 Hz
# 3 On @ 1.25 Hz
# 4 On @ 0.63 Hz
# 7 Hold
def get_dhpf_mode(self):
return self.read_byte(C.MPU6050_RA_ACCEL_CONFIG)
def set_motion_detection_threshold(self, threshold):
self.write_byte(C.MPU6050_RA_MOT_THR, threshold)
def set_motion_detection_duration(self, duration):
self.write_byte(C.MPU6050_RA_MOT_DUR, duration)
def enable_motion_interrupt(self, enabled):
self.set_bitfield(C.MPU6050_RA_INT_ENABLE, C.MPU6050_INTERRUPT_MOT_BIT, 1, 1)
def disable_motion_interrupt(self, enabled):
self.set_bitfield(C.MPU6050_RA_INT_ENABLE, C.MPU6050_INTERRUPT_MOT_BIT, 1, 0)
def get_sensor_avg(self, samples, softstart=100):
"""Return the average readings from the sensors over the
given number of samples. Discard the first softstart
samples to give things time to settle."""
sample = self.read_sensors()
counters = [0] * 7
for i in range(samples + softstart):
# the sleep here is to ensure we read a new sample
# each time
time.sleep_ms(2) # type: ignore[attr-defined]
sample = self.read_sensors()
if i < softstart:
continue
for j, val in enumerate(sample):
counters[j] += val
return SensorReadings(*[x // samples for x in counters])