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Thread: RC100 data packets

  1. RC100 data packets

    Hi everyone,

    I'm trying to run the CM-530 by sending commands from teensy 3.2 , I am generaly using the RC100 communication packets described in robotis manual but I can't get all the buttons values to work. The problem is I can't understand exactly how to structure the low and high byte part of the data. Is there any way I can see the values being send from the RC100 or if you know how to convert the buttons value for example U + 4 = 129 => to communication data format in hex.


  2. #2
    Join Date
    May 2016
    White Plains, NY
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    Re: RC100 data packets

    Can you show me more details? I think you want ( hi-value << 8 ) | Low-value, but I may be misinterpreting your question

  3. #3

    Re: RC100 data packets

    Sorry I did not see this question back then... Also not sure if you are still up here. Would have suggested to take this up on either PJRC forum and/or Robotis forum.

    Awhile ago when I was playing with that controller. I had a simple sketch:
    uint8_t input_line[20];
    uint8_t input_count = 0;
    uint32_t last_packet;
    void setup() {
      pinMode(BOARD_LED_PIN, OUTPUT);
      last_packet = millis();
    void loop() {
      if (Serial.available()) {
        Serial2.print((char);//send data coming from USB to Serial2
      if (Serial2.available()) {
        input_count = 0;
        uint32_t delta_time_between_packets = millis() - last_packet;
        last_packet = millis();
        uint32_t time_first_byte = last_packet;
        uint32_t time_last_input = last_packet;
        while (((millis() - time_last_input) < 15) && (input_count < 6)) {
          if (Serial2.available()) {
            input_line[input_count++] =;
            time_last_input = millis();
        uint32_t delta_time_packet = millis() - time_first_byte;
        Serial.print(delta_time_between_packets, DEC);
        Serial.print(" ");
        Serial.print(delta_time_packet, DEC);
        Serial.print(": ");
        for (uint8_t i = 0; i < input_count; i++) {
          Serial.print(input_line[i], HEX);
          Serial.print(" ");
        Serial.print(": ");
        for (uint8_t i = 0; i < input_count; i++) {
          if ((input_line[i] >= ' ') && (input_line[i] <= '|'))
    That I played with to get an idea of what the controller sent. Don't remember exactly what the data was... But running a simple sketch with that on T3.2 you should be pretty simple to emulate.

    If you look at their documentation:

    You will see in Section 9: that U+4 would compute to the data being sent: as 129 (U=1 + 4=128).
    So 129 in hex is: 0x81 So Data_L = 0x81 and Data_H = 0

    So packet (Section 10) should probably be something like: FF 55 81 7E 00 FF

  4. Re: RC100 data packets

    For example R + 4 which in data is 8 + 128 = 136 then i convert it to hex => 88 so the data packet should be 0xFF 0x55 0x88 and what about the last bits? . Another thing I don't undestand is ~ represents Inverse (1’s Complement) ?

    So packet (Section 10) should probably be something like: FF 55 81 7E 00 FF
    That's the thing i'm not sure what values and how to construct last 3 bits. I know that the value converted to hex must go after [FF] [55] [HERE] but what about [~Data_L] [DATA_H ] [~DATA_H] ?

    I will play around with that sketch when I have time. Very useful.


  5. #5

    Re: RC100 data packets

    ~ is the C/C++ bitwise-not operator. Yes, this is "1's complement"

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