ELM327_Emulator.cpp

/*
 *  ELM327_Emu.cpp
 *
 * Class emulates the serial comm of an ELM327 chip - Used to create an OBDII interface
 *
 * Created: 3/23/2017
 *  Author: Collin Kidder
 */

/*
 Copyright (c) 2017 Collin Kidder

Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:

The above copyright notice and this permission notice shall be included
in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

#include "ELM327_Emulator.h"
#include "BluetoothSerial.h"
#include "config.h"
#include "Logger.h"
#include "utility.h"
#include "esp32_can.h"
#include "can_manager.h"

/*
 * Constructor. Nothing at the moment
 */
ELM327Emu::ELM327Emu() 
{
    
}

/*
 * Initialization of hardware and parameters
 */
void ELM327Emu::setup() {

    tickCounter = 0;
    ibWritePtr = 0;
    ecuAddress = 0x7E0;
    serialBT.begin(settings.btName);
}

/*
 * Send a command to ichip. The "AT+i" part will be added.
 */
void ELM327Emu::sendCmd(String cmd) {
    serialBT.print("AT");
    serialBT.print(cmd);
    serialBT.write(13);
    loop(); // parse the response
}

/*
 * Called in the main loop (hopefully) in order to process serial input waiting for us
 * from the wifi module. It should always terminate its answers with 13 so buffer
 * until we get 13 (CR) and then process it.
 * But, for now just echo stuff to our serial port for debugging
 */

void ELM327Emu::loop() {
    int incoming;
    while (serialBT.available()) {
        incoming = serialBT.read();
        if (incoming != -1) { //and there is no reason it should be -1
            if (incoming == 13 || ibWritePtr > 126) { // on CR or full buffer, process the line
                incomingBuffer[ibWritePtr] = 0; //null terminate the string
                ibWritePtr = 0; //reset the write pointer

                if (Logger::isDebug())
                    Logger::debug(incomingBuffer);
                processCmd();

            } else { // add more characters
                if (incoming != 10 && incoming != ' ') // don't add a LF character or spaces. Strip them right out
                    incomingBuffer[ibWritePtr++] = (char)tolower(incoming); //force lowercase to make processing easier
            }
        } else
            return;
    }
}

/*
*   There is no need to pass the string in here because it is local to the class so this function can grab it by default
*   But, for reference, this cmd processes the command in incomingBuffer
*/
void ELM327Emu::processCmd() {
    String retString = processELMCmd(incomingBuffer);

    serialBT.print(retString);
    if (Logger::isDebug()) {
        char buff[30];
        retString.toCharArray(buff, 30);
        Logger::debug(buff);
    }

}

String ELM327Emu::processELMCmd(char *cmd) 
{
    String retString = String();
    String lineEnding;
    if (bLineFeed) lineEnding = String("\r\n");
    else lineEnding = String("\r");

    if (!strncmp(cmd, "at", 2)) 
    {

        if (!strcmp(cmd, "atz")) 
        { //reset hardware
            retString.concat(lineEnding);
            retString.concat("ELM327 v1.3a");
        }
        else if (!strncmp(cmd, "atsh",4)) //set header address (address we send queries to)
        { 
            size_t idSize = strlen(cmd+4);
            ecuAddress = Utility::parseHexString(cmd+4, idSize);
            Logger::debug("New ECU address: %x", ecuAddress);
            retString.concat("OK");
        }
        else if (!strncmp(cmd, "ate",3)) 
        { //turn echo on/off
            //could support echo but I don't see the need, just ignore this
            retString.concat("OK");
        }
        else if (!strncmp(cmd, "ath",3)) 
        { //turn headers on/off
            if (cmd[3] == '1') bHeader = true;
            else bHeader = false;
            retString.concat("OK");
        }
        else if (!strncmp(cmd, "atl",3)) 
        { //turn linefeeds on/off
            if (cmd[3] == '1') bLineFeed = true;
            else bLineFeed = false;
            retString.concat("OK");
        }
        else if (!strcmp(cmd, "at@1")) 
        { //send device description
            retString.concat("ELM327 Emulator");
        }
        else if (!strcmp(cmd, "ati")) 
        { //send chip ID
            retString.concat("ELM327 v1.3a");
        }
        else if (!strncmp(cmd, "atat",4)) 
        { //set adaptive timing
            //don't intend to support adaptive timing at all
            retString.concat("OK");
        }
        else if (!strncmp(cmd, "atsp",4)) 
        { //set protocol
            //theoretically we can ignore this
            retString.concat("OK");
        }
        else if (!strcmp(cmd, "atdp")) 
        { //show description of protocol
            retString.concat("can11/500");
        }
        else if (!strcmp(cmd, "atdpn")) 
        { //show protocol number (same as passed to sp)
            retString.concat("6");
        }
        else if (!strcmp(cmd, "atd")) 
        { //set to defaults
            retString.concat("OK");
        }
        else if (!strncmp(cmd, "atm", 3)) 
        { //turn memory on/off
            retString.concat("OK");
        }
        else if (!strcmp(cmd, "atrv")) 
        { //show 12v rail voltage
            //TODO: the system should actually have this value so it wouldn't hurt to
            //look it up and report the real value.
            retString.concat("14.2V");
        }
        else 
        { //by default respond to anything not specifically handled by just saying OK and pretending.
            retString.concat("OK");
        }
    }
    else 
    { //if no AT then assume it is a PID request. This takes the form of four bytes which form the alpha hex digit encoding for two bytes
        //there should be four or six characters here forming the ascii representation of the PID request. Easiest for now is to turn the ascii into
        //a 16 bit number and mask off to get the bytes
        CAN_FRAME outFrame;
        outFrame.id = ecuAddress;
        outFrame.extended = false;
        outFrame.length = 8;
        outFrame.rtr = 0;
        outFrame.data.byte[3] = 0xAA; outFrame.data.byte[4] = 0xAA;
        outFrame.data.byte[5] = 0xAA; outFrame.data.byte[6] = 0xAA;
        outFrame.data.byte[7] = 0xAA;
        size_t cmdSize = strlen(cmd);
        if (cmdSize == 4) //generic OBDII codes
        {
            uint32_t valu = strtol((char *) cmd, NULL, 16); //the pid format is always in hex
            uint8_t pidnum = (uint8_t)(valu & 0xFF);
            uint8_t mode = (uint8_t)((valu >> 8) & 0xFF);
            Logger::debug("Mode: %i, PID: %i", mode, pidnum);
            outFrame.data.byte[0] = 2;
            outFrame.data.byte[1] = mode;
            outFrame.data.byte[2] = pidnum;            
        }
        if (cmdSize == 6) //custom PIDs for specific vehicles
        {
            uint32_t valu = strtol((char *) cmd, NULL, 16); //the pid format is always in hex
            uint16_t pidnum = (uint8_t)(valu & 0xFFFF);
            uint8_t mode = (uint8_t)((valu >> 16) & 0xFF);
            Logger::debug("Mode: %i, PID: %i", mode, pidnum);
            outFrame.data.byte[0] = 3;
            outFrame.data.byte[1] = mode;
            outFrame.data.byte[2] = pidnum >> 8;
            outFrame.data.byte[3] = pidnum & 0xFF;
        }
        
        canManager.sendFrame(&CAN0, outFrame);
    }

    retString.concat(lineEnding);
    retString.concat(">"); //prompt to show we're ready to receive again

    return retString;
}

void ELM327Emu::processCANReply(CAN_FRAME &frame)
{
    //at the moment assume anything sent here is a legit reply to something we sent. Package it up properly
    //and send it down the line
    char buff[8];
    if (bHeader) 
    {
        sprintf(buff, "%03X", frame.id);
        serialBT.print(buff);
    }
    for (int i = 0; i < frame.data.byte[0]; i++)
    {
        sprintf(buff, "%02X", frame.data.byte[1+i]);
        serialBT.print(buff);
    }
}