def packet_read(self):
valid = False
picommon.spi_select_device(self.device_port)
data = self.read_bytes(1)
if (data[0] == self.STX):
data.extend(self.read_bytes(2))
size = data[1]
type = data[2]
data.extend(self.read_bytes(size - 3))
checksum = sum(data) & 0xFF
if (checksum == 0):
data = data[3:(size - 1)]
valid = True
if not valid:
data = []
return valid, type, data
def packet_write(self, type, data):
msg = [2, len(data) + 4, type] + data
checksum = (-(sum(msg) & 0xFF)) & 0xFF
msg.append(checksum)
picommon.spi_select_device(self.device_port)
picommon.spi.xfer2(msg)