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Segway S/S-Plus/Loomo on wire bus/protocol

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I am trying to figure out the on wire bus/protocol for either Segway S/S-Plus/Loomo. I did open up the base and saw three open ports as shown in the picture below.


2tgPs8o.pngI could manage to sniff some data from Port 1 (GND, Tx, Rx) and the messages looked something like this

0x5A 0xA5 0x02 0x04 0x06 0x02 0x00 0x00 0x02 0xEF 0XFF

which seems consistent with what others have found. Port 3 seems like a SWD since one of the pin looked like a clk signal (not exactly though). Port 2 seemed more like UART port since one of the pin was held at 3.3V (which I assume would be the Rx pin for my terminal) and the other one was held low. I connected at UART-USB terminal and used pyserial to send exactly the same message that I found earlier but I don't seem to be getting any reply back. I did try using a different source address according to this protocol but again no reply. What I really want to achieve is find a programmatic way of moving the self balancing bot forward. Also attaching my script that I am using for sending the commands below


import serial
import time
import struct

def checksum(buf):
    s = 0
    for c in buf:
        s += c
    return struct.pack("<H", (s & 0xFFFF) ^ 0xFFFF)

def main():
    s = serial.Serial(port='/dev/tty.usbserial-AB0KT24G', baudrate=115200)

    buf = get_first_variable()

    for i in range(256):
        header = b'\x5A\xA5'
        packet = b'\x01' + struct.pack("<B", i) + b'\x07\x01\x40\x1C'
        c = checksum(packet)
        buf = bytearray(header + packet + c)


if __name__ == '__main__':


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  • 2 years later...

Hey boss, did you ever end up figuring this out?? I am currently also trying to do the exact same thing as you described. I can not find any information about how to do this… so if you did manage to do it, I would really appreciate if you could pass on the information. 


Thank You. 

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