src/adafruit_blinka/microcontroller/nova/spi.py

   1 class SPI:
   2     MSB = 0
   3     PAYLOAD_MAX_LENGTH = 64
   4
   5     def __init__(self, clock):
   6         from adafruit_blinka.microcontroller.nova import Connection
   7         self._nova = Connection.getInstance()
   8         self._nova.setOperationMode(0, 'SPI')
   9         self._nova.setClockSPI(0, clock)
  10         self._nova.setModeSPI(0, 0)
  11         self._nova.setIOpinMode(0, 'DOUT')
  12         self._nova.setIOpinMode(1, 'DOUT')
  13         self._nova.beginSPI(0)
  14
  15         # Cpol and Cpha set by mode
  16         # Mode  Cpol Cpha
  17         #  0     0    0
  18         #  1     0    1
  19         #  2     1    0
  20         #  3     1    1
  21
  22     def init(self, baudrate=100000, polarity=0, phase=0, bits=8,
  23                   firstbit=MSB, sck=None, mosi=None, miso=None):
  24         #print("baudrate: " + str(baudrate))
  25         #print("mode: " + str((polarity<<1) | (phase)))
  26         self._nova.setClockSPI(0, baudrate)
  27         self._nova.setModeSPI(0, (polarity<<1) | (phase))
  28
  29     @staticmethod
  30     def getSpiReceivedData(lineOutput):
  31         return (lineOutput.split('RXD ')[1])
  32
  33     @property
  34     def frequency(self):
  35         return self._nova.getClockSPI(0).split('CLK ')[1]
  36
  37     def write(self, buf, start=0, end=None):
  38         end = end if end else len(buf)
  39         chunks, rest = divmod(end - start, self.PAYLOAD_MAX_LENGTH)
  40         for i in range(chunks):
  41             chunk_start = start + i * self.PAYLOAD_MAX_LENGTH
  42             chunk_end = chunk_start + self.PAYLOAD_MAX_LENGTH
  43             buffer_data = buf[chunk_start:chunk_end]
  44             self._nova.clearBuffer(0)
  45             self._nova.writeToBuffer(0, 0, buffer_data)
  46             self._nova.transferBufferSPI(0, chunk_end - chunk_start + 1)
  47         if rest:
  48             buffer_data = buf[-1*rest:]
  49             self._nova.clearBuffer(0)
  50             self._nova.writeToBuffer(0, 0, buffer_data)
  51             self._nova.transferBufferSPI(0, rest)
  52
  53     def readinto(self, buf, start=0, end=None, write_value=0):
  54         end = end if end else len(buf)
  55         for i in range(start, end):
  56             buf[start+i] = int(self.getSpiReceivedData(self._nova.transferSPI(0, write_value)), 16)
  57
  58     def write_readinto(self, buffer_out, buffer_in,  out_start=0, out_end=None, in_start=0, in_end=None):
  59         out_end = out_end if out_end else len(buffer_out)
  60         in_end = in_end if in_end else len(buffer_in)
  61         readlen = in_end-in_start
  62         writelen = out_end-out_start
  63         if readlen > writelen:
  64             # resize out and pad with 0's
  65             tmp = bytearray(buffer_out)
  66             tmp.extend([0] * (readlen - len(buffer_out)))
  67             buffer_out = tmp
  68         i = 0
  69         for data_out in buffer_out:
  70             data_in = int(self.getSpiReceivedData(self._nova.transferSPI(0, data_out)), 16)
  71             if i < readlen:
  72                 buffer_in[in_start+i] = data_in
  73             i += 1