class SPIBus(object):
"""SPI bus access."""
def __init__(self, freq, sc, mo, mi):
self._spi = SPI(sc, mo, mi)
if not self._spi.try_lock():
print("ERROR: busio.SPIBus: no lock for configure()")
else:
try:
self._spi.configure(baudrate=freq)
finally:
self._spi.unlock()
@property
def bus(self):
return self._spi
def write_readinto(self, wbuf, rbuf):
if self._spi.try_lock():
try:
self._spi.write_readinto(wbuf, rbuf)
finally:
self._spi.unlock()
pin_a1 = DigitalInOut(board.D7)
pin_a1.direction = Direction.OUTPUT
pin_b0 = DigitalInOut(board.D5)
pin_b0.direction = Direction.OUTPUT
pin_b1 = DigitalInOut(board.D6)
pin_b1.direction = Direction.OUTPUT
# The h-bridge takes a PWM input, one for each of A and B.
pin_pwm_a = PWMOut(board.D9, frequency=200000, duty_cycle=0)
pin_pwm_b = PWMOut(board.D4, frequency=200000, duty_cycle=0)
# SPI bus connected to the encoder.
spi = SPI(board.SCK, MOSI=board.MOSI, MISO=board.MISO)
spi.try_lock()
spi.configure(baudrate=10000000, polarity=0, phase=1)
spi.unlock()
spi_cs = DigitalInOut(board.A2)
spi_cs.direction = Direction.OUTPUT
def read_encoder():
"""
Returns averaged encoder value in the range (0,_MICROSTEPS_PER_REV).
"""
reading = 0
for _ in range(_ENCODER_SAMPLES):
# Send SPI signal to read the raw value from the magnetic encoder.
spi_cs.value = False
buf = bytearray(2)
spi.try_lock()
spi.write_readinto(b'\xFF\xFF', buf)