-import spidev
-import time
-from adafruit_blinka.agnostic import detector
-
-class SPI:
- MSB = 0
- LSB = 1
- CPHA = 1
- CPOL = 2
-
- baudrate = 100000
- mode = 0
- bits = 8
-
- def __init__(self, portid):
- if isinstance(portid, tuple):
- self._bus_id = portid[0]
- self._device_id = portid[1]
- else:
- self._bus_id = portid
- self._device_id = 0
- self._spi = spidev.SpiDev()
-
- def init(self, baudrate=100000, polarity=0, phase=0, bits=8,
- firstbit=MSB, sck=None, mosi=None, miso=None):
- mode = 0
- if polarity:
- mode |= self.CPOL
- if phase:
- mode |= self.CPHA
-
- self.clock_pin = sck
- self.mosi_pin = mosi
- self.miso_pin = miso
- self.baudrate = baudrate
- self.mode = mode
- self.bits = bits
- self.chip = detector.chip
-
- def set_no_cs(self):
- # No kernel seems to support this, so we're just going to pass
- pass
-
- @property
- def frequency(self):
- return self.baudrate
-
- def write(self, buf, start=0, end=None):
- if not buf:
- return
- if end is None:
- end = len(buf)
- try:
- self._spi.open(self._bus_id, self._device_id)
- self.set_no_cs()
- self._spi.max_speed_hz = self.baudrate
- self._spi.mode = self.mode
- self._spi.bits_per_word = self.bits
- self._spi.writebytes(buf[start:end])
- self._spi.close()
- except FileNotFoundError as not_found:
- print("Could not open SPI device - check if SPI is enabled in kernel!")
- raise
-
- def readinto(self, buf, start=0, end=None, write_value=0):
- if not buf:
- return
- if end is None:
- end = len(buf)
- try:
- self._spi.open(self._bus_id, self._device_id)
- self.set_no_cs()
- self._spi.max_speed_hz = self.baudrate
- self._spi.mode = self.mode
- self._spi.bits_per_word = self.bits
- data = self._spi.xfer3([write_value],(end-start))
- for i in range(end-start): # 'readinto' the given buffer
- buf[start+i] = data[i]
- self._spi.close()
- except FileNotFoundError as not_found:
- print("Could not open SPI device - check if SPI is enabled in kernel!")
- raise
-
- def write_readinto(self, buffer_out, buffer_in, out_start=0,
- out_end=None, in_start=0, in_end=None):
- if not buffer_out or not buffer_in:
- return
- if out_end is None:
- out_end = len(buffer_out)
- if in_end is None:
- in_end = len(buffer_in)
- if out_end - out_start != in_end - in_start:
- raise RuntimeError('Buffer slices must be of equal length.')
- try:
- self._spi.open(self._bus_id, self._device_id)
- self.set_no_cs()
- self._spi.max_speed_hz = self.baudrate
- self._spi.mode = self.mode
- self._spi.bits_per_word = self.bits
- data = self._spi.xfer(list(buffer_out[out_start:out_end+1]))
- for i in range((in_end - in_start)):
- buffer_in[i+in_start] = data[i]
- self._spi.close()
- except FileNotFoundError as not_found:
- print("Could not open SPI device - check if SPI is enabled in kernel!")
- raise