Quick demo code for exploring the Supplyfrrame Cube

cube.py

import serial
import os

s = serial.Serial("/dev/ttyUSB0", baudrate=115200, timeout=0.1)
# timeout: the cube seems to respond in 0.3 sec to "mtu" command

def send(command, s=s):
    s.write(command + "\r")

def receive(s=s):
    """Returns ascii data if it's there, else None"""
    count = 0
    output = None
    while count < 15: # arbitrary
        lookahead = s.readline().strip()
        if lookahead == "+":
            return output
        if "error" in lookahead:
            return None 
        output = lookahead
        count = count + 1

def do(command, s=s):
    send(command)
    response = receive()
    return response

def toBytes(asciiString):
    asciiList = asciiString.split()
    byteList = [chr(int(x)) for x in asciiList]
    return "".join(byteList)

def toASCII(byteString):
    output = ""
    for c in byteString:
        output = output + " %03d" % ord(c)
    return output

def pad(asciiString):
    while len(asciiString) < 512:
        asciiString = asciiString + "\x00"
    return asciiString

def unpad(asciiString):
    return asciiString.strip("\x00")

def help(s=s):
    send("?")
    print s.read(4000).strip()

def accelerometer(s=s):
    return [int(x) for x in do("mau").split()][0:3]

if __name__ == "__main__":

    ## Initialize encryption: store 8 blocks of random data in block 32 
    do("w64") 
    do("mtf8")
    ## Test first block of random secret
    do("r64")
    do("mfu") # looks random to me.  :)

    ## Copy message over into buffer B
    superSecret = "Hello World!"
    send("mub")
    send(pad(superSecret))
    receive() # cube acknowledges with a "+" -- this clears it out
    receive() # Why twice?
    print toBytes(do("mbu")) # verify

    ## Encrypt with key in 32
    do("r64")
    encrypted = do("xbu")
    print encrypted 

    ## Decrypt 
    send("muc")
    send(toBytes(encrypted))
    receive()
    receive()
    encryptedC = do("mcu") # verify encrypted in buffer C
    do("r64")
    decoded = do("xcu")
    print unpad(toBytes(decoded))
    
    ## Decrypting with wrong key 
    ## Key read/write pointers update on each "move" command, so it'll be right
    ## on the second try.
    print do("r62")
    print do("xcu")
    print do("xcu")
    print do("xcu")