class SPI:
def __init__(self,
bus_index: int,
dev_index: int,
freq: int = DEFAULT_FREQ):
self.bus = bus_index
self.dev = dev_index
self.freq = freq
self._spi = None
self._open()
def __del__(self):
self._close()
def _open(self):
if not self._spi:
self._spi = SpiDev()
try:
self._spi.open(self.bus, self.dev)
except FileNotFoundError:
raise SPIError(self.bus, self.dev)
self._spi.max_speed_hz = self.freq
def _close(self):
if self._spi:
self._spi.close()
self._spi = None
def send(self, data: Union[bytes, List[int]]):
self._spi.writebytes2(bytes(data))
class SPIimplementation(SPI):
"""SPI imlementation wrapping spidev library. Extends :class:`SPI`.
Args:
port (int): SPI port on raspberry pi.
devive (int): SPI device of raspberry.
Raises:
ImportError: If spidev is not installed.
"""
def __init__(self, port, device):
self._port = port
self._device = device
self._interface = None
if SpiDev is None:
raise ImportError('failed to import spidev')
self._interface = SpiDev()
self._interface.open(port, device)
self._interface.max_speed_hz = 1000000
def read(self, n):
"""Read n words from spi
Args:
n (int): The number of bytes to read from spi.
"""
return self._interface.readbytes(n)
# TODO: Check writebytes2 for large lists
def write(self, data):
"""Write data to spi
Args:
data (list): A list with integers to be writter to the device.
"""
self._interface.writebytes2(data)
def read_write(self, data):
"""
Writes data (a list of integer words where each word is assumed to have
:attr:`bits_per_word` bits or less) to the SPI interface, and reads an
equivalent number of words, returning them as a list of integers.
"""
return self._interface.xfer2(data)
def close(self):
if self._interface is not None:
self._interface.close()
self._interface = None
def _get_clock_mode(self):
return self._interface.mode
def _set_clock_mode(self, value):
self._interface.mode = value
def _get_lsb_first(self):
return self._interface.lsbfirst
def _set_lsb_first(self, value):
self._interface.lsbfirst = bool(value)
def _get_select_high(self):
return self._interface.cshigh
def _set_select_high(self, value):
self._interface.cshigh = bool(value)
def _get_bits_per_word(self):
return self._interface.bits_per_word
def _set_bits_per_word(self, value):
self._interface.bits_per_word = value
