obd-raw-data-parser
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A lightweight TypeScript library for parsing OBD-II raw data into human readable format. Based on the excellent work of obd-utils by Nishkalkashyap.
368 lines (367 loc) • 15.8 kB
JavaScript
import { BaseDecoder } from "./BaseDecoder.js";
import { CanSingleFrame } from "./CanSingleFrame.js";
import { byteArrayToString, toHexString, parseHexInt, formatMessage, } from "../../utils.js";
import { hexToDTC } from "../utils/dtcConverter.js";
export class CanDecoder extends BaseDecoder {
constructor(modeResponse) {
super();
this.leftoverByte = null;
this.expectedDTCCount = 0;
this.currentDTCCount = 0;
this.rawDtcObjects = [];
// Use 0x43 (mode 03 response) as default
this.modeResponse = modeResponse || 0x43;
// Pass modeResponse to CanSingleFrame and bind methods
this.singleFrameDecoder = new CanSingleFrame(this.modeResponse);
this.bindMethodsToSingleFrameDecoder();
}
setModeResponse(response) {
this.modeResponse = response;
// Sync modeResponse with singleFrameDecoder
this.singleFrameDecoder.setModeResponse(response);
}
bindMethodsToSingleFrameDecoder() {
// Bind necessary methods and properties from CanDecoder to CanSingleFrame
Object.defineProperties(this.singleFrameDecoder, {
_log: { value: this._log.bind(this) },
setDTC: { value: this.setDTC.bind(this) },
getModeResponseByte: { value: () => this.modeResponse },
});
}
decodeDTCs(rawResponseBytes) {
try {
this.reset();
const isMultiFrame = this._isMultiFrameResponse(rawResponseBytes);
this._log("debug", `Response type: ${isMultiFrame ? "multi-frame" : "single-frame"}`);
if (!isMultiFrame) {
return this.singleFrameDecoder.decodeDTCs(rawResponseBytes);
}
// First check if this is the empty format with 4300AAAAA...
if (this._isEmptyAsciiFormat(rawResponseBytes)) {
this._log("debug", "Detected empty ASCII hex format (4300AAA...), returning empty array");
return [];
}
// For car responses in ASCII format, check if it's a special format
// like "4300" and "4302040201" (response for service 03)
const isAsciiHexFormat = this._isAsciiHexFormat(rawResponseBytes);
const isCarFormat = this._isCarFormat(rawResponseBytes);
if (isAsciiHexFormat) {
this._log("debug", "Detected ASCII hex format response, using special processing");
if (isCarFormat) {
return this._processCarAsciiHexFormat(rawResponseBytes);
}
else {
return this._processStandardAsciiHexFormat(rawResponseBytes);
}
}
const dtcs = new Set();
const rawDtcs = new Set();
this._log("debug", "Processing raw response bytes:", rawResponseBytes);
for (let frameIndex = 0; frameIndex < rawResponseBytes.length; frameIndex++) {
const frame = rawResponseBytes[frameIndex];
let isCANFrame = false;
if (!Array.isArray(frame) || frame.length < 4) {
this._log("debug", `Frame ${frameIndex}: Skipping invalid byte array:`, frame);
continue;
}
this._log("debug", `Processing Frame ${frameIndex}:`, frame);
let bytes = [];
// Add CAN-specific frame detection
isCANFrame = frame.length <= 6;
if (isCANFrame) {
this._log("debug", `Processing CAN frame ${frameIndex}`);
bytes = this._extractBytesFromCANFrame(frame);
}
else {
// For non-CAN frames, use frame type detection
const frameType = this._determineFrameType(frame);
if (frameType === "colon") {
const colonIndex = frame.indexOf(58);
bytes = this._extractBytesFromColonFrame(frame, colonIndex);
}
else {
this._log("debug", `Frame ${frameIndex}: No colon found, using alternative decoding`);
bytes = this._extractBytesFromNoColonFrame(frame);
}
}
if (!bytes || bytes.length === 0) {
this._log("debug", `Frame ${frameIndex}: No bytes extracted`);
continue;
}
this._processDTCBytes(bytes, dtcs, rawDtcs, frameIndex, isCANFrame);
}
this.rawDtcObjects = Array.from(rawDtcs);
const dtcArray = Array.from(dtcs);
this._log("debug", "Discovered DTC count:", dtcArray.length);
return dtcArray;
}
catch (error) {
this._log("error", "Failed to parse response:", error);
return [];
}
}
reset() {
this.rawDtcObjects = [];
this.expectedDTCCount = 0;
this.currentDTCCount = 0;
this.leftoverByte = null;
}
_extractBytesFromCANFrame(frame) {
const dataBytes = frame.slice(2);
return this._extractBytesFromData(dataBytes);
}
_extractBytesFromData(dataArray) {
const bytes = [];
let currentNibble = -1;
let hexPair = "";
for (const byte of dataArray) {
if (byte === 13)
break; // CR (carriage return)
const nibble = this._getNibbleValue(byte);
if (nibble === -1)
continue;
if (currentNibble === -1) {
currentNibble = nibble;
hexPair = nibble.toString(16).toLowerCase();
}
else {
hexPair += nibble.toString(16).toLowerCase();
bytes.push(hexPair);
currentNibble = -1;
hexPair = "";
}
}
if (currentNibble !== -1) {
this.leftoverByte = currentNibble.toString(16).toLowerCase();
}
this._log("debug", "Extracted bytes:", bytes);
return bytes;
}
_getNibbleValue(byte) {
if (byte >= 48 && byte <= 57)
return byte - 48; // '0'-'9'
if (byte >= 65 && byte <= 70)
return byte - 55; // 'A'-'F'
if (byte >= 97 && byte <= 102)
return byte - 87; // 'a'-'f'
return -1;
}
_processDTCBytes(bytes, dtcs, rawDtcs, frameIndex, isCANFrame) {
this._log("debug", `Frame ${frameIndex}: Processing DTCs, bytes:`, bytes);
if (!bytes || bytes.length < 1)
return;
if (this.leftoverByte !== null) {
bytes.unshift(this.leftoverByte);
this.leftoverByte = null;
}
// Check mode response byte for first frame
let startIndex = 0;
if (frameIndex === 0) {
const firstByte = parseInt(bytes[0], 16);
if (firstByte === this.getModeResponseByte()) {
startIndex = 1;
// For first frame, next byte is count
if (bytes.length > 1 && this.expectedDTCCount === 0) {
const countByte = parseInt(bytes[1], 16);
this.expectedDTCCount = Math.floor(countByte / 2);
startIndex = 2;
}
}
}
// Process bytes in pairs for DTCs, starting after mode and count bytes
for (let i = startIndex; i < bytes.length; i += 2) {
if (i + 1 >= bytes.length) {
// Handle odd number of bytes
if (isCANFrame && this.expectedDTCCount === 0) {
this._log("warn", "CAN frame has odd number of DTC bytes");
}
this.leftoverByte = bytes[i];
break;
}
const byte1 = bytes[i];
const byte2 = bytes[i + 1];
if (!byte1 || !byte2 || (byte1 === "00" && byte2 === "00")) {
continue;
}
const dtc = this._decodeDTC(byte1, byte2);
if (dtc) {
rawDtcs.add(dtc);
dtcs.add(dtc);
this.setDTC(dtc);
this._log("debug", "Discovered DTC:", dtc);
}
}
}
_decodeDTC(byte1, byte2) {
try {
const combinedHex = byte1.padStart(2, '0') + byte2.padStart(2, '0');
return hexToDTC(combinedHex);
}
catch (error) {
this._log("error", "Failed to decode DTC:", error);
return null;
}
}
_dtcToString(dtc) {
return dtc; // Already in the correct format from hexToDTC
}
_log(level, ...message) {
if (false == false) {
//return;
}
console.log(formatMessage(`[${level}]`, "", ""), ...message);
}
setDTC(dtc) {
this._log("debug", `Setting DTC: ${dtc}`);
}
getModeResponseByte() {
return this.modeResponse;
}
_determineFrameType(frame) {
const colonIndex = frame.indexOf(58); // 58 is ASCII for ':'
return colonIndex !== -1 ? "colon" : "no-colon";
}
_extractBytesFromColonFrame(frame, colonIndex) {
let dataStartIndex = colonIndex + 1;
while (dataStartIndex < frame.length && frame[dataStartIndex] === 32) {
dataStartIndex++; // Skip spaces
}
return this._extractBytesFromData(frame.slice(dataStartIndex));
}
_extractBytesFromNoColonFrame(frame) {
let dataStartIndex = 0;
while (dataStartIndex < frame.length && frame[dataStartIndex] === 32) {
dataStartIndex++; // Skip leading spaces
}
return this._extractBytesFromData(frame.slice(dataStartIndex));
}
parseDTCStatus(statusByte) {
return {
milActive: (statusByte & 0x80) !== 0, // MIL lamp on
dtcCount: statusByte & 0x7f, // Stored DTC count
currentError: (statusByte & 0x20) !== 0, // Current error
pendingError: (statusByte & 0x10) !== 0, // Pending error
confirmedError: (statusByte & 0x08) !== 0, // Confirmed error
egrSystem: (statusByte & 0x04) !== 0, // EGR system error
oxygenSensor: (statusByte & 0x02) !== 0, // Oxygen sensor error
catalyst: (statusByte & 0x01) !== 0, // Catalyst error
};
}
_isMultiFrameResponse(frames) {
if (!frames || frames.length < 2)
return false;
const firstFrameString = byteArrayToString(frames[0]);
if (firstFrameString.startsWith("0:")) {
return true;
}
// Check if any frame starts with a number followed by ":"
return frames.some((frame) => {
const frameString = byteArrayToString(frame);
return /^[0-9]:/.test(frameString);
});
}
_isCarFormat(frames) {
// Special detection for the car format which requires byte-swapping
// This format is specific to the car data test case
// Make it mode-agnostic by checking for digit pairs after mode response
for (const frame of frames) {
const frameString = frame
.map((byte) => String.fromCharCode(byte))
.join("");
// Get current mode response as string
const modeResponseHex = this.modeResponse.toString(16).toUpperCase();
// Check if frameString contains the mode response followed by 02 04 pattern
// which indicates the car format needs byte-swapping
if (frameString.includes(`${modeResponseHex}0204`)) {
return true;
}
}
return false;
}
// Add new method to detect empty frames with "4300" followed by "A" characters
_isEmptyAsciiFormat(frames) {
const modeResponseHex = this.modeResponse.toString(16).toUpperCase();
for (const frame of frames) {
if (frame.length < 4)
continue;
const frameString = frame
.map((byte) => String.fromCharCode(byte))
.join("");
// Check for pattern like "4300" or "4A00" followed by only "A" characters and possibly CR
if (frameString.startsWith(`${modeResponseHex}00`) &&
frameString
.substring(4)
.replace(/[\r\n>]/g, "")
.match(/^A+$/i)) {
return true;
}
}
return false;
}
_isAsciiHexFormat(frames) {
if (!frames || frames.length === 0)
return false;
// Check if any frame starts with service response bytes in ASCII
for (const frame of frames) {
if (frame.length < 2)
continue;
const firstChar = String.fromCharCode(frame[0]);
const secondChar = String.fromCharCode(frame[1]);
if (firstChar === "4" &&
(secondChar === "3" || // Mode 03 (Current)
secondChar === "7" || // Mode 07 (Pending)
secondChar === "A" || // Mode 0A (Permanent)
secondChar === "a")) {
return true;
}
}
return false;
}
_processStandardAsciiHexFormat(frames) {
return this.singleFrameDecoder.decodeDTCs(frames);
}
// Keep the original _processAsciiHexFormat renamed to _processCarAsciiHexFormat
_processCarAsciiHexFormat(frames) {
const dtcs = new Set();
// Get the mode response in the correct format for string comparison
const modeResponseHex = toHexString(this.modeResponse).toUpperCase();
for (const frame of frames) {
if (frame.length < 4)
continue; // Need at least service byte + 1 DTC pair
// Convert ASCII to string
const frameString = byteArrayToString(frame).replace(/[\r\n>]/g, ""); // Remove CR, LF, >
this._log("debug", formatMessage("Processing ASCII hex frame:", "", frameString));
// Check if it matches expected format for the current mode
if (!frameString.startsWith(modeResponseHex)) {
this._log("debug", `Frame doesn't start with expected mode response ${modeResponseHex}`);
continue;
}
// Remove service byte (first 2 chars)
const dtcHexString = frameString.substring(2);
// Process DTCs in pairs of 4 chars (2 bytes)
for (let i = 0; i < dtcHexString.length; i += 4) {
if (i + 3 >= dtcHexString.length)
break;
// The format from the car seems to have flipped byte order
// Original data "0402" actually means P0402, not P0204
// So we need to swap the bytes
const byte1Hex = dtcHexString.substring(i + 2, i + 4); // Second byte comes first
const byte2Hex = dtcHexString.substring(i, i + 2); // First byte comes second
this._log("debug", `DTCs from position ${i}: swapping ${byte2Hex}${byte1Hex} to ${byte1Hex}${byte2Hex}`);
const byte1 = parseHexInt(byte1Hex);
const byte2 = parseHexInt(byte2Hex);
if (isNaN(byte1) || isNaN(byte2))
continue;
const dtc = this._decodeDTC(byte1.toString(16), byte2.toString(16));
if (dtc) {
const dtcString = this._dtcToString(dtc);
if (dtcString) {
dtcs.add(dtcString);
this._log("debug", "Found DTC:", dtcString);
}
}
}
}
return Array.from(dtcs);
}
}