src/adafruit_blinka/microcontroller/ft232h/spi.py

   1 from adafruit_blinka.microcontroller.ft232h.pin import Pin
   2
   3 class SPI:
   4     MSB = 0
   5
   6     def __init__(self):
   7         from pyftdi.spi import SpiController
   8         self._spi = SpiController(cs_count=1)
   9         self._spi.configure('ftdi:///1')
  10         self._port = self._spi.get_port(0)
  11         self._port.set_frequency(100000)
  12         self._port._cpol = 0
  13         self._port._cpha = 0
  14         # Change GPIO controller to SPI
  15         Pin.ft232h_gpio = self._spi.get_gpio()
  16
  17     def init(self, baudrate=100000, polarity=0, phase=0, bits=8,
  18                   firstbit=MSB, sck=None, mosi=None, miso=None):
  19         self._port.set_frequency(baudrate)
  20         self._port._cpol = polarity
  21         self._port._cpha = phase
  22
  23     @property
  24     def frequency(self):
  25         return self._port.frequency
  26
  27     def write(self, buf, start=0, end=None):
  28         end = end if end else len(buf)
  29         chunks, rest = divmod(end - start, self._spi.PAYLOAD_MAX_LENGTH)
  30         for i in range(chunks):
  31             chunk_start = start + i * self._spi.PAYLOAD_MAX_LENGTH
  32             chunk_end = chunk_start + self._spi.PAYLOAD_MAX_LENGTH
  33             self._port.write(buf[chunk_start:chunk_end])
  34         if rest:
  35             self._port.write(buf[-1*rest:])
  36
  37     def readinto(self, buf, start=0, end=None, write_value=0):
  38         end = end if end else len(buf)
  39         result = self._port.read(end-start)
  40         for i, b in enumerate(result):
  41             buf[start+i] = b
  42
  43     def write_readinto(self, buffer_out, buffer_in,  out_start=0, out_end=None, in_start=0, in_end=None):
  44         out_end = out_end if out_end else len(buffer_out)
  45         in_end = in_end if in_end else len(buffer_in)
  46         result = self._port.exchange(buffer_out[out_start:out_end],
  47                                      in_end-in_start, duplex=True)
  48         for i, b in enumerate(result):
  49             buffer_in[in_start+i] = b