Very basic test code for controlling DFRobot 3-wire LCD with a Raspberry Pi

dfrobot lcd.py

# For Raspberry Pi.
# Code based on: http://www.dfrobot.com/wiki/index.php?title=SPI_LED_Module_(SKU:DFR0090)#Sample_Code
import re
import spidev


# 0-9
NUMS = (0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,0x90)

# a-z
CHARS = (0xA0,0x83,0xa7,0xa1,0x86,0x8e,0xc2,0x8b,0xe6,0xe1,
         0x89,0xc7,0xaa,0xc8,0xa3,0x8c,0x98,0xce,0x9b,0x87,
         0xc1,0xe3,0xd5,0xb6,0x91,0xb8)


class LED(object):
    def __init__(self):
        self._spi = spidev.SpiDev()
        self._spi.open(0, 0)

    def send(self, chars, clear=True):
        # Clear
        if clear:
            self._spi.xfer2([0xff]*8)

        # Expects string of [a-z0-9. ]
        out = []
        for c in chars.lower():
            if re.match('[0-9]', c) is not None:
                idx = int(c)
                out.append(NUMS[idx])
            elif re.match('[a-z]', c) is not None:
                idx = ord(c) - 97
                out.append(CHARS[idx])
            elif c == '.':
                # Try to efficiently include the '.'
                # using AND with previous char
                out[-1] = out[-1] & 0x7f
            elif c == ' ':
                out.append(0xff)

        self._spi.xfer2(out[::-1])


if __name__ == '__main__':
    led = LED()
    led.send('Raspbery')