ELEC60013-ES-CW1/lis3dh.py

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"""Library for interacting with LIS3DH triple-axis accelerometer."""
from importlib.resources import read_text
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from re import S
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from tabnanny import check
import smbus2
from time import sleep
# Register addresses
_CTRL_REG1 = bytes([0x20])
_CTRL_REG2 = bytes([0x21])
_CTRL_REG3 = bytes([0x22])
_CTRL_REG4 = bytes([0x23])
_CTRL_REG5 = bytes([0x24])
_CTRL_REG6 = bytes([0x25])
_REF_REG = bytes([0x26])
_STATUS_REG = bytes([0x27])
_OUT_X_L = bytes([0x28])
_OUT_X_H = bytes([0x29])
_OUT_Y_L = bytes([0x2A])
_OUT_Y_H = bytes([0x2B])
_OUT_Z_L = bytes([0x2C])
_OUT_Z_H = bytes([0x2D])
_INT1_CFG = bytes([0x30])
_INT1_SRC = bytes([0x31])
_INT1_THS = bytes([0x32])
_INT1_DURATION = bytes([0x33])
_INT2_CFG = bytes([0x34])
_INT2_SRC = bytes([0x35])
_INT2_THS = bytes([0x36])
_INT2_DURATION = bytes([0x37])
_CLICK_CFG = bytes([0x38])
# Config flags
SAMPLERATE_1HZ = bytes([0x17])
SAMPLERATE_10HZ = bytes([0x27])
SAMPLERATE_25HZ = bytes([0x37])
HP_DISABLE = bytes([0x00])
CTRL_REG3_V = bytes([0x40])
CTRL_REG4_V = bytes([0x00]) # sensitivity set to 2g
CTRL_REG5_V = bytes([0x08])
INT1_THS_V = bytes([0x16]) # free-fall threshold at 350 mg
INT1_DURATION_V = bytes([0x03])
INT1_CFG_V = bytes([0x95])
EMPTY = bytes([0x00])
class lis3dh:
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def __init__(self, i2cBus, resolution=2, samplerate=10, i2cAddress=0x18):
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sleep(0.005)
self.i2c = i2cBus
self.addr = i2cAddress
self.samplerate = samplerate
i2cBus.pec = True # enable smbus2 Packet Error Checking
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res_modes = {
2: 0b00, 4: 0b01,
8: 0b10, 16: 0b11
}
sample_modes = {
0:0x0, 1:0x1, 10:0x2, 25:0x3, 50:0x4,
100:0x5, 200:0x6, 400:0x7
}
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# Check if user-entered values are correct
if resolution in res_modes:
self.resolution = resolution
else:
raise Exception("Invalid resolution.")
if samplerate in sample_modes:
self.samplerate = sample_modes[samplerate]
else:
raise Exception("Invalid sample rate.")
# First try; configure beginning from 0x20
config0 = smbus2.i2c_msg.write(self.addr, [0x20,(sample_modes[samplerate]<<4)|0xF]) # Initialise in low power mode
config1 = smbus2.i2c_msg.write(self.addr, [0xC1,0x00,0x00,0x00|self.resolution,0x00,0x00,0x00])
config2 = smbus2.i2c_msg.write(self.addr, [0xB2,0x00,0x00]) # Configure 0x32 with MSB = 1 to increment
config3 = smbus2.i2c_msg.write(self.addr, [0x30,0x00]) # Configure 0x30
config4 = smbus2.i2c_msg.write(self.addr, [0x24,0x00]) # Configure 0x24 again
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self.i2c.i2c_rdwr(config0, config1, config2, config3, config4)
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def readAll(self) -> list:
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'''Read acceleration data from all axes. Returns values as a list [X,Y,Z].'''
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check_status = smbus2.i2c_msg.write(self.addr, [0x27])
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x = smbus2.i2c_msg.read(self.addr, 1)
y = smbus2.i2c_msg.read(self.addr, 1)
z = smbus2.i2c_msg.read(self.addr, 1)
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prepare_x = smbus2.i2c_msg.write(self.addr, [0x29])
prepare_y = smbus2.i2c_msg.write(self.addr, [0x2B])
prepare_z = smbus2.i2c_msg.write(self.addr, [0x2D])
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status = smbus2.i2c_msg.read(self.addr, 1)
self.i2c.i2c_rdwr(check_status, status)
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while status.buf[0][0] & 0b1111 != 0b1111: # Wait for data to be available
sleep(0.001)
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self.i2c.i2c_rdwr(check_status, status)
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if status.buf[0][0] & 0b1111 == 0b1111: # If data is available, read
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self.i2c.i2c_rdwr(prepare_x, x)
self.i2c.i2c_rdwr(prepare_y, y)
self.i2c.i2c_rdwr(prepare_z, z)
X = int.from_bytes(x.buf[0],"big")
Y = int.from_bytes(y.buf[0],"big")
Z = int.from_bytes(z.buf[0],"big")
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new_values = []
for D in [X,Y,Z]:
MSB = D >> 7
if MSB == 1:
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res = (-128 + (D - 128))*self.resolution/128
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else:
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res = (D*self.resolution)/128
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new_values.append(res)
return new_values
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else:
return None # Should never get here lol