2014-08-02 11:51:18 +00:00
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"""
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Driver for accelerometer on STM32F4 Discover board.
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Assumes it's a LIS302DL MEMS device.
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2014-08-10 21:26:20 +00:00
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Sets accelerometer range at +-2g.
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Returns list containing X,Y,Z axis acceleration values in 'g' units (9.8m/s^2).
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2014-08-02 11:51:18 +00:00
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See:
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STM32Cube_FW_F4_V1.1.0/Drivers/BSP/Components/lis302dl/lis302dl.h
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STM32Cube_FW_F4_V1.1.0/Drivers/BSP/Components/lis302dl/lis302dl.c
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STM32Cube_FW_F4_V1.1.0/Drivers/BSP/STM32F4-Discovery/stm32f4_discovery.c
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STM32Cube_FW_F4_V1.1.0/Drivers/BSP/STM32F4-Discovery/stm32f4_discovery.h
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STM32Cube_FW_F4_V1.1.0/Drivers/BSP/STM32F4-Discovery/stm32f4_discovery_accelerometer.c
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STM32Cube_FW_F4_V1.1.0/Drivers/BSP/STM32F4-Discovery/stm32f4_discovery_accelerometer.h
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STM32Cube_FW_F4_V1.1.0/Projects/STM32F4-Discovery/Demonstrations/Src/main.c
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"""
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from pyb import Pin
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from pyb import SPI
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READWRITE_CMD = const(0x80)
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MULTIPLEBYTE_CMD = const(0x40)
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LIS302DL_WHO_AM_I_ADDR = const(0x0f)
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2014-08-26 16:23:00 +00:00
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LIS302DL_WHO_AM_I_VAL = const(0x3b)
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2014-08-02 11:51:18 +00:00
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LIS302DL_CTRL_REG1_ADDR = const(0x20)
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2014-08-10 21:26:20 +00:00
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LIS302DL_OUT_X = const(0x29)
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2014-08-26 21:41:27 +00:00
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LIS302DL_OUT_Y = const(0x2b)
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LIS302DL_OUT_Z = const(0x2d)
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2014-08-10 21:26:20 +00:00
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# Configuration for 100Hz sampling rate, +-2g range
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2014-08-26 21:41:27 +00:00
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LIS302DL_CONF = const(0b01000111)
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2014-08-10 21:26:20 +00:00
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2014-08-26 21:41:27 +00:00
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def convert_raw_to_g(x):
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2014-08-10 21:26:20 +00:00
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if x & 0x80:
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2014-08-26 21:41:27 +00:00
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x = x - 256
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return x * 18 / 1000
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2014-08-02 11:51:18 +00:00
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class STAccel:
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def __init__(self):
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self.cs_pin = Pin('PE3', Pin.OUT_PP, Pin.PULL_NONE)
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self.cs_pin.high()
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self.spi = SPI(1, SPI.MASTER, baudrate=328125, polarity=0, phase=1, bits=8)
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2014-08-26 21:41:27 +00:00
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self.write_bytes(LIS302DL_CTRL_REG1_ADDR, bytearray([LIS302DL_CONF]))
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if self.read_id() != LIS302DL_WHO_AM_I_VAL:
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2014-08-26 16:23:00 +00:00
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raise Exception('LIS302DL accelerometer not present')
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2014-08-02 11:51:18 +00:00
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2014-08-26 21:41:27 +00:00
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def read_bytes(self, addr, nbytes):
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2014-08-02 11:51:18 +00:00
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if nbytes > 1:
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addr |= READWRITE_CMD | MULTIPLEBYTE_CMD
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else:
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addr |= READWRITE_CMD
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self.cs_pin.low()
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self.spi.send(addr)
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2014-08-26 21:41:27 +00:00
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#buf = self.spi.send_recv(bytearray(nbytes * [0])) # read data, MSB first
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buf = self.spi.recv(nbytes)
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2014-08-02 11:51:18 +00:00
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self.cs_pin.high()
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return buf
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2014-08-26 21:41:27 +00:00
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def write_bytes(self, addr, buf):
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2014-08-02 11:51:18 +00:00
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if len(buf) > 1:
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addr |= MULTIPLEBYTE_CMD
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self.cs_pin.low()
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self.spi.send(addr)
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for b in buf:
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self.spi.send(b)
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self.cs_pin.high()
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def read_id(self):
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2014-08-26 21:41:27 +00:00
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return self.read_bytes(LIS302DL_WHO_AM_I_ADDR, 1)[0]
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2014-08-02 11:51:18 +00:00
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2014-08-26 21:41:27 +00:00
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def x(self):
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return convert_raw_to_g(self.read_bytes(LIS302DL_OUT_X, 1)[0])
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def y(self):
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return convert_raw_to_g(self.read_bytes(LIS302DL_OUT_Y, 1)[0])
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def z(self):
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return convert_raw_to_g(self.read_bytes(LIS302DL_OUT_Z, 1)[0])
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def xyz(self):
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val = self.read_bytes(LIS302DL_OUT_X, 5)
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return [convert_raw_to_g(val[0]),
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convert_raw_to_g(val[2]),
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convert_raw_to_g(val[4])]
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