DbwNode does not forward correct Brake Command in specific firmware versions

[Jean Paul Talledo Vilela]

Reviewing the CAN TX traffic from the DataSpeed ROS Node to the DataSpeed Brake Module, it was found for old firmware revisions, the commanded “percent” does not go from 0 - 100%. Instead, it goes from 0.15 to 50%.

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It seems the issue is related to the fwd flag:

  bool fwd_abs = firmware_.findModule(M_ABS).valid(); // Does the ABS braking module exist?
  bool fwd_bpe = firmware_.findPlatform(M_BPEC) >= FIRMWARE_CMDTYPE; // Minimum required BPEC firmware version
  bool fwd = !pedal_luts_; // Forward command type, or apply pedal LUTs locally
  fwd |= fwd_abs; // The local pedal LUTs are for the BPEC module, the ABS module requires forwarding
  fwd &= fwd_bpe; // Only modern BPEC firmware supports forwarding the command type

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I.e. Firmware 2.0.0 will set:

fwd_abs = 0

fwd_bpe = 0

fwd = !pedal_luts_ → 1

fwd |= fw_abs → 1

fwd &= fwd_bpe → 0

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    case dbw_mkz_msgs::BrakeCmd::CMD_PERCENT:
      if (fwd) {
        ptr->CMD_TYPE = dbw_mkz_msgs::BrakeCmd::CMD_PERCENT;
        ptr->PCMD = std::clamp<float>(msg->pedal_cmd * UINT16_MAX, 0, UINT16_MAX);
      } else {
        ptr->CMD_TYPE = dbw_mkz_msgs::BrakeCmd::CMD_PEDAL;
        ptr->PCMD = std::clamp<float>(brakePedalFromPercent(msg->pedal_cmd) * UINT16_MAX, 0, UINT16_MAX);
      }

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When commanding CMD_PERCENT, it uses the BrakeLUT Table due to fwd is set to 0

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