in_end = in_end if in_end else len(buffer_in)
port = self._spi.get_port(self.cs, self.freq, self.mode)
result = port.exchange(buffer_out[out_start:out_end],
- in_end-in_start)
+ in_end-in_start, duplex=True)
for i, b in enumerate(result):
buffer_in[in_start+i] = b