def read_adc(spi: busio.SPI, channel: int) -> int:
""" Read a single ADC channel of the MCP3008 """
# TODO: This is still kinda slow, investigate Python's 'spidev'
# library or https://iosoft.blog/2020/06/11/fast-data-capture-raspberry-pi/
rx_buf = bytearray(3)
tx_buf = bytearray((0x01, 0x80 | (channel << 4), 0x00))
with open(f'/sys/class/gpio/gpio{CS_PIN}/value', 'w') as cs_file:
cs_file.write('0')
spi.write_readinto(tx_buf, rx_buf)
with open(f'/sys/class/gpio/gpio{CS_PIN}/value', 'w') as cs_file:
cs_file.write('1')
raw_val = ((rx_buf[1] & 0x3) << 8) | rx_buf[2]
return raw_val
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()