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OBD9141.cpp
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OBD9141.cpp
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/*
* Copyright (c) 2015, Ivor Wanders
* MIT License, see the LICENSE.md file in the root folder.
*/
#include "OBD9141.h"
OBD9141::OBD9141(){};
void OBD9141::begin(OBD_SERIAL_DATA_TYPE & serial_port, uint8_t rx_pin, uint8_t tx_pin){
this->serial = &serial_port;
this->tx_pin = tx_pin;
this->rx_pin = rx_pin;
// Enable the pullup on the Rx Pin, this is not changed by set_port.
pinMode(this->rx_pin, INPUT);
digitalWrite(this->rx_pin, HIGH);
this->set_port(true); // prevents calling this->serial->end() before start.
use_kwp_ = false;
}
void OBD9141::set_port(bool enabled){
if (enabled){
// Work around the incorrect pinmode configuration in Due.
#ifdef ARDUINO_SAM_DUE
g_APinDescription[this->rx_pin].pPort -> PIO_PDR = g_APinDescription[this->rx_pin].ulPin;
g_APinDescription[this->tx_pin].pPort -> PIO_PDR = g_APinDescription[this->tx_pin].ulPin;
#endif
this->serial->begin(OBD9141_KLINE_BAUD);
} else {
this->serial->end();
#ifdef ARDUINO_SAM_DUE
g_APinDescription[this->rx_pin].pPort -> PIO_PER = g_APinDescription[this->rx_pin].ulPin;
g_APinDescription[this->tx_pin].pPort -> PIO_PER = g_APinDescription[this->tx_pin].ulPin;
#endif
pinMode(this->tx_pin, OUTPUT);
digitalWrite(this->tx_pin, HIGH);
}
}
void OBD9141::kline(bool enabled){
digitalWrite(this->tx_pin, enabled);
}
uint8_t OBD9141::checksum(void* b, uint8_t len){
uint8_t ret = 0;
for (uint8_t i=0; i < len; i++){
ret += reinterpret_cast<uint8_t*>(b)[i];
}
return ret;
}
void OBD9141::write(uint8_t b){
// OBD9141print("w: "); OBD9141println(b);
this->serial->write(b);
this->serial->setTimeout(OBD9141_REQUEST_ECHO_MS_PER_BYTE * 1 + OBD9141_WAIT_FOR_ECHO_TIMEOUT);
uint8_t tmp[1]; // temporary variable to read into.
this->serial->readBytes(tmp, 1);
}
void OBD9141::write(void* b, uint8_t len){
for (uint8_t i=0; i < len ; i++){
// OBD9141print("w: ");OBD9141println(reinterpret_cast<uint8_t*>(b)[i]);
this->serial->write(reinterpret_cast<uint8_t*>(b)[i]);
delay(OBD9141_INTERSYMBOL_WAIT);
}
this->serial->setTimeout(OBD9141_REQUEST_ECHO_MS_PER_BYTE * len + OBD9141_WAIT_FOR_ECHO_TIMEOUT);
uint8_t tmp[len]; // temporary variable to read into.
this->serial->readBytes(tmp, len);
}
bool OBD9141::request(void* request, uint8_t request_len, uint8_t ret_len)
{
if (use_kwp_)
{
// have to modify the first bytes.
uint8_t rbuf[request_len];
memcpy(rbuf, request, request_len);
// now we modify the header, the payload is the request_len - 3 header bytes
rbuf[0] = (0b11<<6) | (request_len - 3);
rbuf[1] = 0x33; // second byte should be 0x33
return (this->requestKWP(&rbuf, request_len) == ret_len);
}
return request9141(request, request_len, ret_len);
}
bool OBD9141::request9141(void* request, uint8_t request_len, uint8_t ret_len){
uint8_t buf[request_len+1];
memcpy(buf, request, request_len); // copy request
buf[request_len] = this->checksum(&buf, request_len); // add the checksum
this->write(&buf, request_len+1);
// wait after the request, officially 30 ms, but we might as well wait
// for the data in the readBytes function.
// set proper timeout
this->serial->setTimeout(OBD9141_REQUEST_ANSWER_MS_PER_BYTE * ret_len + OBD9141_WAIT_FOR_REQUEST_ANSWER_TIMEOUT);
memset(this->buffer, 0, ret_len+1);
//OBD9141print("Trying to get x bytes: "); OBD9141println(ret_len+1);
if (this->serial->readBytes(this->buffer, ret_len+1)){
// OBD9141print("R: ");
// for (uint8_t i=0; i< (ret_len+1); i++){
// OBD9141print(this->buffer[i]);OBD9141print(" ");
// };OBD9141println();
return (this->checksum(&(this->buffer[0]), ret_len) == this->buffer[ret_len]);// have data; return whether it is valid.
} else {
OBD9141println("Timeout on reading bytes.");
return false; // failed getting data.
}
}
uint8_t OBD9141::request(void* request, uint8_t request_len){
if (use_kwp_)
{
// have to modify the first bytes.
uint8_t rbuf[request_len];
memcpy(rbuf, request, request_len);
// now we modify the header, the payload is the request_len - 3 header bytes
rbuf[0] = (0b11<<6) | (request_len - 3);
rbuf[1] = 0x33; // second byte should be 0x33
return requestKWP(rbuf, request_len);
}
bool success = true;
// wipe the entire buffer to ensure we are in a clean slate.
memset(this->buffer, 0, OBD9141_BUFFER_SIZE);
// create the request with checksum.
uint8_t buf[request_len+1];
memcpy(buf, request, request_len); // copy request
buf[request_len] = this->checksum(&buf, request_len); // add the checksum
// manually write the bytes onto the serial port
// this does NOT read the echoes.
OBD9141print("W: ");
#ifdef OBD9141_DEBUG
for (uint8_t i=0; i < (request_len+1); i++){
OBD9141print(buf[i]);OBD9141print(" ");
};OBD9141println();
#endif
for (uint8_t i=0; i < request_len+1 ; i++){
this->serial->write(reinterpret_cast<uint8_t*>(buf)[i]);
delay(OBD9141_INTERSYMBOL_WAIT);
}
// next step, is to read the echo from the serial port.
this->serial->setTimeout(OBD9141_REQUEST_ECHO_MS_PER_BYTE * 1 + OBD9141_WAIT_FOR_ECHO_TIMEOUT);
uint8_t tmp[request_len+1]; // temporary variable to read into.
this->serial->readBytes(tmp, request_len+1);
OBD9141print("E: ");
for (uint8_t i=0; i < request_len+1; i++)
{
#ifdef OBD9141_DEBUG
OBD9141print(tmp[i]);OBD9141print(" ");
#endif
// check if echo is what we wanted to send
success &= (buf[i] == tmp[i]);
}
// so echo is dealt with now... next is listening to the reply, which is a variable number.
// set the timeout for the first read to include the wait for answer timeout
this->serial->setTimeout(OBD9141_REQUEST_ANSWER_MS_PER_BYTE * 1 + OBD9141_WAIT_FOR_REQUEST_ANSWER_TIMEOUT);
uint8_t answer_length = 0;
// while readBytes returns a byte, keep reading.
while (this->serial->readBytes(&(this->buffer[answer_length]), 1) && (answer_length < OBD9141_BUFFER_SIZE))
{
answer_length++;
this->serial->setTimeout(OBD9141_REQUEST_ANSWER_MS_PER_BYTE * 1);
}
OBD9141println();OBD9141print("A (");OBD9141print(answer_length);OBD9141print("): ");
#ifdef OBD9141_DEBUG
for (uint8_t i=0; i < answer_length; i++){
OBD9141print(this->buffer[i]);OBD9141print(" ");
};OBD9141println();
#endif
// next, calculate the checksum
bool checksum = (this->checksum(&(this->buffer[0]), answer_length-1) == this->buffer[answer_length - 1]);
OBD9141print("C: ");OBD9141println(checksum);
OBD9141print("S: ");OBD9141println(success);
OBD9141print("R: ");OBD9141println(answer_length - 1);
if (checksum && success)
{
return answer_length - 1;
}
return 0;
}
uint8_t OBD9141::requestKWP(void* request, uint8_t request_len){
uint8_t buf[request_len+1];
memcpy(buf, request, request_len); // copy request
buf[request_len] = this->checksum(&buf, request_len); // add the checksum
this->write(&buf, request_len+1);
// wait after the request, officially 30 ms, but we might as well wait
// for the data in the readBytes function.
// set proper timeout
this->serial->setTimeout(OBD9141_REQUEST_ANSWER_MS_PER_BYTE * 1 + OBD9141_WAIT_FOR_REQUEST_ANSWER_TIMEOUT);
memset(this->buffer, 0, OBD9141_BUFFER_SIZE);
// Example response: 131 241 17 193 239 143 196 0
// Try to read the fmt byte.
if (!(this->serial->readBytes(this->buffer, 1)))
{
return 0; // failed reading the response byte.
}
const uint8_t msg_len = (this->buffer[0]) & 0b111111;
// If length is zero, there is a length byte at the end of the header.
// This is likely very rare, we do not handle this for now.
// This means that we should now read the 2 addressing bytes, the payload
// and the checksum byte.
const uint8_t remainder = msg_len + 2 + 1;
OBD9141print("Rem: ");OBD9141println(remainder);
const uint8_t ret_len = remainder + 1;
OBD9141print("ret_len: ");OBD9141println(ret_len);
this->serial->setTimeout(OBD9141_REQUEST_ANSWER_MS_PER_BYTE * (remainder + 1));
//OBD9141print("Trying to get x bytes: "); OBD9141println(ret_len+1);
if (this->serial->readBytes(&(this->buffer[1]), remainder)){
OBD9141print("R: ");
for (uint8_t i=0; i< (ret_len+1); i++){
OBD9141print(this->buffer[i]);OBD9141print(" ");
};OBD9141println();
const uint8_t calc_checksum = this->checksum(&(this->buffer[0]), ret_len - 1);
OBD9141print("calc cs: ");OBD9141println(calc_checksum);
OBD9141print("buf cs: ");OBD9141println(this->buffer[ret_len - 1]);
if (calc_checksum == this->buffer[ret_len - 1])
{
return ret_len - 1; // have data; return whether it is valid.
}
} else {
OBD9141println("Timeout on reading bytes.");
return 0; // failed getting data.
}
return 0;
}
/*
No header description to be found on the internet?
for 9141-2:
raw request: {0x68, 0x6A, 0xF1, 0x01, 0x0D}
returns: 0x48 0x6B 0x11 0x41 0x0D 0x00 0x12
returns 1 byte
total of 7 bytes.
raw request: {0x68, 0x6A, 0xF1, 0x01, 0x00}
returns 0x48 0x6B 0x11 0x41 0x00 0xBE 0x3E 0xB8 0x11 0xCA
returns 3 bytes
total of 10 bytes
Mode seems to be 0x40 + mode, unable to confirm this though.
for ISO 14230 KWP:
First byte lower 6 bits are length, first two bits always 0b11?
raw request: {0xc2, 0x33, 0xf1, 0x01, 0x0d, 0xf4}
returns 0x83 0xf1 0x11 0x41 0xd 0x0 0xd3
raw request: {0xc2, 0x33, 0xf1, 0x01, 0x0c, 0xf3}
returns 0x84, 0xf1, 0x11, 0x41, 0x0c, 0x0c, 0x4c, 0x2b, 0xf3
*/
bool OBD9141::getPID(uint8_t pid, uint8_t mode, uint8_t return_length){
uint8_t message[5] = {0x68, 0x6A, 0xF1, mode, pid};
// header of request is 5 long, first three are always constant.
bool res = this->request(&message, 5, return_length+5);
// checksum is already checked, verify the PID.
if (this->buffer[4] != pid){
return false;
}
return res;
}
bool OBD9141::getCurrentPID(uint8_t pid, uint8_t return_length){
return this->getPID(pid, 0x01, return_length);
}
bool OBD9141::clearTroubleCodes(){
uint8_t message[4] = {0x68, 0x6A, 0xF1, 0x04};
// 0x04 without PID value should clear the trouble codes or
// malfunction indicator lamp.
// No data is returned to this request, we expect the request itself
// to be returned.
bool res = this->request(&message, 4, 4);
return res;
}
uint8_t OBD9141::readTroubleCodes()
{
uint8_t message[4] = {0x68, 0x6A, 0xF1, 0x03};
uint8_t response = this->request(&message, 4);
if (response >= 4)
{
// OBD9141print("T: ");OBD9141println((response - 4) / 2);
return (response - 4) / 2; // every DTC is 2 bytes, header was 4 bytes.
}
return 0;
}
uint8_t OBD9141::readPendingTroubleCodes()
{
uint8_t message[4] = {0x68, 0x6A, 0xF1, 0x07};
uint8_t response = this->request(&message, 4);
if (response >= 4)
{
// OBD9141print("T: ");OBD9141println((response - 4) / 2);
return (response - 4) / 2; // every DTC is 2 bytes, header was 4 bytes.
}
return 0;
}
uint8_t OBD9141::readUint8(){
return this->buffer[5];
}
uint16_t OBD9141::readUint16(){
return this->buffer[5]*256 + this->buffer[6]; // need to reverse endianness
}
uint8_t OBD9141::readUint8(uint8_t index){
return this->buffer[5 + index];
}
uint32_t OBD9141::readUint32(){
return (uint32_t(this->buffer[5]) << 24) | (uint32_t(this->buffer[6]) << 16) | (uint32_t(this->buffer[7]) << 8) | this->buffer[8]; // need to reverse endianness
}
uint8_t OBD9141::readBuffer(uint8_t index){
return this->buffer[index];
}
uint16_t OBD9141::getTroubleCode(uint8_t index)
{
return *reinterpret_cast<uint16_t*>(&(this->buffer[index*2 + 4]));
}
bool OBD9141::initImpl(bool check_v1_v2){
use_kwp_ = false;
// this function performs the ISO9141 5-baud 'slow' init.
this->set_port(false); // disable the port.
this->kline(true);
delay(OBD9141_INIT_IDLE_BUS_BEFORE); // no traffic on bus for 3 seconds.
OBD9141println("Before magic 5 baud.");
// next, send the startup 5 baud init..
this->kline(false); delay(200); // start
this->kline(true); delay(400); // first two bits
this->kline(false); delay(400); // second pair
this->kline(true); delay(400); // third pair
this->kline(false); delay(400); // last pair
this->kline(true); delay(200); // stop bit
// this last 200 ms delay could also be put in the setTimeout below.
// But the spec says we have a stop bit.
// done, from now on it the bus can be treated ad a 10400 baud serial port.
OBD9141println("Before setting port.");
this->set_port(true);
OBD9141println("After setting port.");
uint8_t buffer[1];
this->serial->setTimeout(300+200);
// wait should be between 20 and 300 ms long
// read first value into buffer, should be 0x55
if (this->serial->readBytes(buffer, 1)){
OBD9141print("First read is: "); OBD9141println(buffer[0]);
if (buffer[0] != 0x55){
return false;
}
} else {
OBD9141println("Timeout on read 0x55.");
return false;
}
// we get here after we have passed receiving the first 0x55 from ecu.
this->serial->setTimeout(20); // w2 and w3 are pauses between 5 and 20 ms
uint8_t v1=0, v2=0; // sent by car: (either 0x08 or 0x94)
// read v1
if (!this->serial->readBytes(buffer, 1)){
OBD9141println("Timeout on read v1.");
return false;
} else {
v1 = buffer[0];
OBD9141print("read v1: "); OBD9141println(v1);
}
// read v2
if (!this->serial->readBytes(buffer, 1)){
OBD9141println("Timeout on read v2.");
return false;
} else {
v2 = buffer[0];
OBD9141print("read v2: "); OBD9141println(v2);
}
OBD9141print("v1: "); OBD9141println(v1);
OBD9141print("v2: "); OBD9141println(v2);
// these two should be identical according to the spec.
if (check_v1_v2) {
if (v1 != v2){
return false;
}
}
// we obtained w1 and w2, now invert and send it back.
// tester waits w4 between 25 and 50 ms:
delay(30);
this->write(~v2);
this->serial->setTimeout(50); // w5 is same as w4... max 50 ms
// finally, attempt to read 0xCC from the ECU, indicating succesful init.
if (!this->serial->readBytes(buffer, 1)){
OBD9141println("Timeout on 0xCC read.");
return false;
} else {
// OBD9141print("read 0xCC?: "); OBD9141println(buffer[0], HEX);
if ((buffer[0] == 0xCC)){ // done if this is inverse of 0x33
delay(OBD9141_INIT_POST_INIT_DELAY);
// this delay is not in the spec, but prevents requests immediately
// after the finishing of the init sequency.
return true; // yay! we are initialised.
} else {
return false;
}
}
}
bool OBD9141::init(){
// Normal 9141-2 slow init, check v1 == v2.
return initImpl(true);
}
bool OBD9141::initKWPSlow(){
// KWP slow init, v1 == 233, v2 = 143, don't check v1 == v2.
bool res = initImpl(false);
// After the init, switch to kwp.
use_kwp_ = true;
return res;
}
bool OBD9141::initKWP(){
use_kwp_ = true;
// this function performs the KWP2000 fast init.
this->set_port(false); // disable the port.
this->kline(true); // set to up
delay(OBD9141_INIT_IDLE_BUS_BEFORE); // no traffic on bus for 3 seconds.
OBD9141println("Before 25 ms / 25 ms startup.");
this->kline(false); delay(25); // start with 25 ms low
this->kline(true); delay(25); // 25 ms high.
// immediately follow this by a startCommunicationRequest
OBD9141println("Enable port.");
this->set_port(true);
// startCommunicationRequest message:
uint8_t message[4] = {0xC1, 0x33, 0xF1, 0x81};
// checksum (0x66) is calculated by request method.
// Send this request and read the response
if (this->requestKWP(&message, 4) == 6) {
// check positive response service ID, should be 0xC1.
if (this->buffer[3] == 0xC1) {
// Not necessary to do anything with this data?
return true;
} else {
return false;
}
}
return false;
}
void OBD9141::decodeDTC(uint16_t input_bytes, uint8_t* output_string){
const uint8_t A = reinterpret_cast<uint8_t*>(&input_bytes)[0];
const uint8_t B = reinterpret_cast<uint8_t*>(&input_bytes)[1];
const static char type_lookup[4] = {'P', 'C', 'B', 'U'};
const static char digit_lookup[16] = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'};
// A7-A6 is first dtc character, error type:
output_string[0] = type_lookup[A >> 6];
// A5-A4 is second dtc character
output_string[1] = digit_lookup[(A >> 4) & 0b11];
// A3-A0 is third dtc character.
output_string[2] = digit_lookup[A & 0b1111];
// B7-B4 is fourth dtc character
output_string[3] = digit_lookup[B >> 4];
// B3-B0 is fifth dtc character
output_string[4] = digit_lookup[B & 0b1111];
}