// test program, no license, open source, no warranty given
// reads canbus from Holley HEFI 3rd Party CAN Communications Protocol (RacePAK)
// about 100 times per second using an MCP2515 canbus module.

// libraries used to simplify using the can bus interface, display and EEprom memory
#include <Arduino.h>
#include <mcp_can.h>
#include <SPI.h>

const float versionNumber = 1.1; // so you can tell which version is burnt into the chip

// *********************** CAN related variables *****************
unsigned char CANLen = 0;
unsigned char buf[8];
#define CAN0_INT 2 // define CANbus interrupt pin
const int spiChipSelectPin = 10;
MCP_CAN CAN0(spiChipSelectPin); // Set CS pin
unsigned long lastTimeCANgotMsg; // to check for CANBUS timeouts
long unsigned int rxId;

// pins for MCP2515 CAN bus board to arduino nano
// Int D2
// SCK D13
// SI D11
// SO D12
// CS D10
// GND
// VCC

union Data { // overlay CAN payload with Long intgeger
unsigned char payloadArray[4]; // 8 byte payload area to the CAN BUS
unsigned long int payload;
};

int currRpm; // RPM xx,xxx
float currInjPulsewidth; // in milliseconds xx.x
float currTiming; // in degrees xx.x
int currMap; // in kPa xxx.x
float currBattery; // in volts xx.x
int currCoolant; // in F xxx
int lbsPerHourFromHolley; // in lbs/hour x,xxx

/* ++++++++++++++++++++++++++++++++++++++++++++++++++++*/
void setup() { // runs once when device is powered up

Serial.begin(115200);
Serial.print(F("Holley CANbus Ver: ")); Serial.println(versionNumber);
Serial.println(F("Starting CANbus"));
// CANbus setup
while (CAN0.begin(MCP_ANY, CAN_1000KBPS, MCP_8MHZ) != CAN_OK) { // init CAN bus : baudrate = 1000k
Serial.println(F("CAN BUS Shield init fail"));
delay(500);
}
Serial.println(F("CAN BUS Shield init ok!"));

pinMode(CAN0_INT, INPUT);
CAN0.setMode(MCP_NORMAL); // Set operation mode to normal so the MCP2515 sends acks to received data.
} // end of setup

/* ++++++++++++++++++++++++++++++++++++++++++++++++++++*/
void loop(){ // runs and loops forever
check_for_CAN_message(); // checks for next CAN message from Holley
check_for_CAN_timeout(); // checks for timeout in CAN messages
// do something with the data you read from the Holley CANBUS
} // end of loop

/* ++++++++++++++++++++++++++++++++++++++++++++++++++++*/
void check_for_CAN_message() {

if(!digitalRead(CAN0_INT)) { // If CAN0_INT pin is low, read receive buffer

CAN0.readMsgBuf(&rxId, &CANLen, buf); // Read data: len = data length, buf = data byte(s)
union Data data; // overlay 4 char buffer for conversion to unsigned long int
rxId = rxId & 0x7FFFF000; // filter out serial number .
switch ( rxId ) {
case 0x1E005000: // 0x1E005000 fuel packet
data.payloadArray[0] = buf[7]; // shift the data from CAN buffer to unsigned long
data.payloadArray[1] = buf[6];
data.payloadArray[2] = buf[5];
data.payloadArray[3] = buf[4];
lbsPerHourFromHolley = (int)(data.payload / 256); // remove Holley 256 multiplier

data.payloadArray[0] = buf[3]; // shift the data from CAN buffer to unsigned long
data.payloadArray[1] = buf[2];
data.payloadArray[2] = buf[1];
data.payloadArray[3] = buf[0];
currInjPulsewidth = (float)data.payload / 256.0;
break;

case 0x1E001000: //rpm packet
data.payloadArray[0] = buf[7]; // shift the data from CAN buffer to unsigned long
data.payloadArray[1] = buf[6];
data.payloadArray[2] = buf[5];
data.payloadArray[3] = buf[4];
currRpm = (int)(data.payload / 256);
break;

case 0x1E015000: //Timing packet
data.payloadArray[0] = buf[3]; // shift the data from CAN buffer to unsigned long
data.payloadArray[1] = buf[2];
data.payloadArray[2] = buf[1];
data.payloadArray[3] = buf[0];
currTiming = (float)data.payload / 256.0;
break;

case 0x1E019000: //MAP packet
data.payloadArray[0] = buf[3]; // shift the data from CAN buffer to unsigned long
data.payloadArray[1] = buf[2];
data.payloadArray[2] = buf[1];
data.payloadArray[3] = buf[0];
currMap = (int)(data.payload / 256);
break;

case 0x1E021000: //coolant packet
data.payloadArray[0] = buf[7]; // shift the data from CAN buffer to unsigned long
data.payloadArray[1] = buf[6];
data.payloadArray[2] = buf[5];
data.payloadArray[3] = buf[4];
currCoolant = (int)(data.payload / 256);
break;

case 0x1E025000: //Battery
data.payloadArray[0] = buf[7]; // shift the data from CAN buffer to unsigned long
data.payloadArray[1] = buf[6];
data.payloadArray[2] = buf[5];
data.payloadArray[3] = buf[4];
currBattery = (float)data.payload / 256.0;
break;

default: // debug printing to serial
return;
break;

lastTimeCANgotMsg = millis();
}// end switch
}// end CAN msg avail
} // end check_for_CAN_message

/* ++++++++++++++++++++++++++++++++++++++++++++++++++++*/
void check_for_CAN_timeout() { // if a CAN failure occurs
if ( millis() - lastTimeCANgotMsg > 500 ) {
Serial.println(F("Canbus Timeout"));
lastTimeCANgotMsg = millis();
// zero out values because the CAN timed out
}
} // end check_for_CAN_timeout

// This a test program, no warranties are implied or given. Pentastar brushless fan, GM temp sensor V1
// Use, copy any modify this test program any way you want, at your own risk. Then test, test, test
// It reads a stock GM LS temp sensor connected to and ECM. Assumed ECM has 2.5k ohm pullup to 5V
// Pentastar fan: Freq = 12Hz, 95% duty = full, 11% = min, no PWM = off PWM signal is 12 volt, Temp in F.
#include <PWM.h>
/*----------------------- User adjustable variables and preferences section ---------------------------------*/
// FYI a PWM duty ranges from 0 to 255 which is equivalent to 0% to 100%.
// OHM for temp sensor from 2005 silverado sensor table. yes it's a curve but the range is so small, a straight line interpolation will work fine.
const float tempSensorOhmsAtForLowSpeed = 350.0; // above this ohmage, fan should be off (less than roughly 170F)
const float tempSensorOhmsForHighSpeed = 230.0; // below this ohm reading, the fan should be on full (greater than roughly 195F)
const float seriesECMresistorOhms = 2500.0; // The ohms of the series reistor in the ECM (to 5V)
const int acOnMinPwmPct = 25; // If the A/C is on, this is the minumum PWM duty percentage

// adjust these for PWN to for fan start and fan full on
const int slowSpeedFanDuty = 26; // Duty Cycle for 11% ( Off Fan Speed ( 11% of 255 )
const int fanOnFullDuty = 230; // Duty Cycle for 90% ( Full Fan Speed ( 90% of 255 ) 90% instead of 95% to be on the safe side so fan wont shut off when hot

/*----------------------- end of User adjustable variables and preferences -----------------------------------*/
const int fanPwmOutPin = 9; // Arduino PWMS this pin between 0 or 5 volts.
const int tempSensorPin = A0; // Pin to read analog voltage from the temp sensor.
const int acClutchPin = A1; // Pin to A/C Clutch via 1K/10K Voltage Devider
int analogReadingForFanSlowSpeed = (int) (1023.0 * (tempSensorOhmsAtForLowSpeed / (seriesECMresistorOhms + tempSensorOhmsAtForLowSpeed)));
int analogReadingForFanFullSpeed = (int) (1023.0 * (tempSensorOhmsForHighSpeed / (seriesECMresistorOhms + tempSensorOhmsForHighSpeed)));
int acOnMinPWMDuty;

void setup() { /* ++++++++++++++++++ Setup is run once when the arduino boots ++++++++++++++++++++++++++*/
Serial.begin(115200); // set up serial port for 115200 baud (optional)
InitTimersSafe(); // set pwm frequency to 12 Hz for Pentastar pwm signal
SetPinFrequency(fanPwmOutPin, 12); // set pwm frequency to 12 Hz for Pentastar brushless fan
} // end setup


void loop() { /* ++++++++++++++++++ Main Loop, continuously loops forever ++++++++++++++++++++++++++++*/

if (analogRead(acClutchPin) > 20 ) { // A/C is on
acOnMinPWMDuty = (255 * acOnMinPwmPct) / 100; // If the A/C is on, this is the minumum actual PWM duty
} else {
acOnMinPWMDuty = 0;
}

int analogTempReading = analogRead(tempSensorPin); // read temperature sensor (range 0 to 1023)
int duty = map(analogTempReading, analogReadingForFanSlowSpeed, analogReadingForFanFullSpeed, slowSpeedFanDuty, fanOnFullDuty ); // calc PWM Duty

if (duty < acOnMinPWMDuty) { // assign minimum duty if A/C is on.
duty = acOnMinPWMDuty;
}

int constrainedDuty = constrain(duty, 0, fanOnFullDuty ); // PWM duty is never allowed outside of min or max duties

pwmWrite(fanPwmOutPin, 255 - constrainedDuty); // send PWM to output pin, invert for 12V transistor

Serial.print("analogTempReading = "); Serial.println(analogTempReading);
Serial.print("constrainedDuty = "); Serial.println(constrainedDuty);

delay(1000);
} // end main loop