Prostar A/C code for Arduino

Truck_AC_v02a.ino

/*
 * Prostar Air Conditioner Arduino Sketch
 * 08-09-2017 by Rawze.
 * Use at own risk.
 */

#include "Arduino.h"

//##########################################################

//hardware connections ...
#define LED_PIN 6
#define COMPRESSOR_PIN 8
#define FAN_PIN 9
#define PRESS_SENSOR_PIN (unsigned char)A0
#define EVAP_TEMP_PIN (unsigned char)A1

/* Define the hardware pin logic condition for relays. Some relay boards use reversed logic to
 * turn on their relays.
 */
#define RELAY_ON false
#define RELAY_OFF true




//##########################################################
/*
 * Some Hex Value feedback on input pin 'PRESS_SENSOR_PIN' that were measured while using an
 * A/C pressure gauge test set. This list is used for converting/interpolating raw values to
 * actual pressures.
*/
#define TABLE_MAX_ENTRIES	20
const int press_table[TABLE_MAX_ENTRIES][2] {
	//table structure: {raw value, psi}.
	{0x001C,0},		//full vacuum.
	{0x0033,14},	//1 atmosphere (14 psi) empty system.
	{0x0086,43},	//about 43psi
	{0x00BC,70},	//about 70psi
	{0x00E6,100},	//about 100psi
	{0x0183,175},	//about 175psi
	{0x019C,200},	//about 200psi
	{0x01AC,215},	//about 200psi
	{0x01BC,225},	//about 225psi
	{0x0215,250},	//about 250psi 533  91, 75,
	{0x0270,325},	//about 325psi 624
	{0x02A5,350},	//about 350psi 677
	{0x02B5,360},	//about 350psi 693

	{0x7FFF,0x7FFF},	//end of table marker.

};

//##########################################################
/*
 * Some Hex Value feedback on input pin 'EVAP_TEMP_PIN' that were measured while using a
 * temp gun. This list is used for converting/interpolating raw values to
 * actual temperature in F.
*/
const int temp_table[TABLE_MAX_ENTRIES][2] {
	//table structure: {raw value, degrees F}.
	{0x0000,0},			//??.
	{0x0072,36},		//about 36-F.
	{0x00AD,83},		//about 83-F.
	{0x00BC,98},		//about 98-F.
	{0x00BF,103},		//about 103-F.
	{0x00D3,113},		//about 113-F.

	{0x7FFF,0x7FFF},	//end of table.

};

//##########################################################
/* System Settings...
 *
 * MIN_SYSTEM_PRESSURE: - Below this pressure, the system is assumed to be out of refrigerant.
 * The compressor should not run when the system is empty to prevent damage.
 *
 * MAX_SYSTEM_PRESSURE: - Above this pressure, the system is assumed to be overheated or in
 * an over-pressure state. The compressor should not run to prevent damage to the system
 * or the compressor.
 *
 * FAN_ON_PRESSURE: - Above this pressure, the condenser is assumed to be reaching excess
 * temperatures and the engine fan should be engaged to lower it.
 *
 * SAFE_PRESSURE: - At or below this pressure, the system is considered in its "safe zone
 * pressure", indicating engine fan assistance is no longer required.
 *
 * COMPRESSOR_RESTART_DELAY(Milliseconds): - This delay is used to prevent sudden re-start
 * of the compressor when an over-pressure condition occurs.
 *
 * COMPRESSOR_DEBOUNCE_DELAY(Milliseconds): - Prevents the compressor from turning on/off
 * too quickly and burning out the clutch.
 *
 * FAN_OFF_DELAY(Milliseconds): - This delay is used as an additional on-time for the engine fan
 * once the system pressure has dropped below the "safe zone pressure". It is used as a de-bounce
 * for to prevent excess or frequent on/off cycles.
 *
 * DE_ICE_DURATION(Milliseconds): - Span of time to prevent re-start of the compressor once the
 * evaporater core is below a min temp. NOTE: Compressor debounce delay will be added to this time
 * during a re-start.
 *
 * EVAP_MIN_TEMP(F): - Min temp the core is allowed to get before compressor is shut down.
 *
 * EVAP_ALLOWED_TEMP(F): - Temp that must be reached before the compressor is allowed to re-start
 * after it has been turned off.
 *
 */
#define MIN_SYSTEM_PRESSURE 45
#define MAX_SYSTEM_PRESSURE 360
#define FAN_ON_PRESSURE 320
#define SAFE_PRESSURE 215

#define COMPRESSOR_RESTART_DELAY 20000
#define COMPRESSOR_DEBOUNCE_DELAY 5000
#define FAN_OFF_DELAY 25000
#define DE_ICE_DURATION 17000 // 17000 = 22 sec. (de-ice duration(17 seconds) + compressor de-bounce delay(5 more seconds)).

#define EVAP_MIN_TEMP 31
#define EVAP_ALLOWED_TEMP 43

/*
 * Enable/Disable the serial port feedback of the compressor hex values. This is only used
 * for testing/debugging purposes. It can be Commented out when not needed.
 */
#define TERMINAL_AVAIL
#define STATUS_MSG_INTERVAL		600


//##########################################################
class Switch_T { //Standard Switch Template class by Rawze (08-09-2017).
public:
	void	animate(uint32_t _now) {
		if( m_duration && ((_now - m_start_time) > m_duration) ) {
			m_duration = 0;
			m_state = !m_state;
		}
	}
	void	DelayedOn(uint32_t _now, uint32_t duration){ m_start_time = _now; m_duration = duration; m_state = false; }
	void	DelayedOff(uint32_t _now, uint32_t duration){ m_start_time = _now; m_duration = duration; m_state = true; }
	bool	GetState(){ return m_state; }
	bool	IsBusy(){ return (m_duration > 0); }
	bool	IsInNonBusyState(bool state){ return ( (m_state == state) && (m_duration == 0) ); }
	void	Reset(bool state = false) {m_duration = 0; m_start_time = 0; m_state = state;}
	void	SetState(bool state){m_duration = 0; m_state = state; }
	void	ToggleState(){ m_state = !m_state; }

private:
	bool		m_state = false;
	uint32_t	m_duration = 0;
	uint32_t	m_start_time = 0;
};

//##########################################################
/*Quick Interpolate a value from range A into range B. by Rawze 05-12-2016.
 * Great for conversion of values by way of a lookup table or for scaling
 * values up/down, or simply into a different range.
 */
template <typename _T> _T interpolate(_T val, _T i_min, _T i_max, _T o_min, _T o_max ){
	float _v=(float)val, _il=(float)i_min, _ih=(float)i_max, _ol=(float)o_min, _oh=(float)o_max;
	float i_span = _ih - _il; if(!i_span) return 0; //prevent div by 0.
	float o_span = _oh - _ol; if(!o_span) return 0; //prevent div from 0.
	i_span = (o_span / i_span);
	i_span = _ol + ((_v - _il) * i_span);
	return (_T)(i_span);
}
//##########################################################
/* Use a lookup table to find an analog value.
 * CAUTION: The routine assumes the table is sort ordered min to max from 0 to
 * highest entry down the left hand column.
 * Assumed table structure: {raw value, result}.
 */
int GetAnalogVal(const int lookup_value, const int table[][2]){

	//create a reference to the table structure.
	enum {table_col_left = 0,table_col_right = 1};

	//start at the bottom/lowest entry.
	int _ptr = 0;
	int _upper_left = table[_ptr][table_col_left];
	int _upper_right = table[_ptr][table_col_right];

	if(lookup_value <= _upper_left) { return _upper_right; } //at or below min range?.

	//find the entry that is slightly too high. Skip the lowest, we already checked it.
	for (_ptr = 1; _ptr < TABLE_MAX_ENTRIES; ++_ptr ){
		//grab the next pair.
		_upper_left = table[_ptr][table_col_left];
		_upper_right = table[_ptr][table_col_right];

		if(_upper_left > lookup_value){ break; } //slightly higher?

		if(_upper_left == 0x7FFF || _upper_left == lookup_value ){
			return _upper_right;  //out of range, or a quick reply in case we got an exact hit.
		}
	}

	//Out of range check just in case we hit the end of the table.
	if( _ptr == TABLE_MAX_ENTRIES  ){ return 0x7FFF; }

	--_ptr; //back up one so we can obtain the lower bounds to interpolate from.
	int _lower_left = table[_ptr][table_col_left];
	int _lower_right = table[_ptr][table_col_right];

	int _entry_min = table[_ptr][1];
	int _psi_min = table[_ptr][0];
	return interpolate<int>(
			lookup_value,		//lookup value to scale/convert.
			_lower_left,		//input range min. one row back from our upper.
			_upper_left,		//input range max.
			_lower_right,		// opt range min. one row back from our last result.
			_upper_right		//opt range max.
	);
}


//globals...
//##########################################################
Switch_T CompressorSwitch;		//On.Off switch for the A/C compressor clutch. logic true = run the compressor
Switch_T EngineFanSwitch;		//On.Off switch for the engine fan. logic true = run the fan.
Switch_T EvaporatorTempSwitch;	//On.Off safety switch for the evaporater core to prevent freezing. logic true = in range.

#ifdef TERMINAL_AVAIL
	Switch_T SerialTimer;		//Trigger for displaying data to the serial terminal.
#endif //~TERMINAL_AVAIL



//##########################################################
void setup()
{
	//Setup IO pins...
		pinMode(PRESS_SENSOR_PIN, INPUT);
		pinMode(EVAP_TEMP_PIN, INPUT);

		pinMode(LED_PIN, OUTPUT);
		pinMode(COMPRESSOR_PIN, OUTPUT);
		pinMode(FAN_PIN, OUTPUT);

		digitalWrite(COMPRESSOR_PIN, RELAY_OFF); //apply compressor state.
		digitalWrite(FAN_PIN, RELAY_OFF); //apply engine fan state.

	//set initial state.
		CompressorSwitch.SetState(false);
		EngineFanSwitch.SetState(false);
		EvaporatorTempSwitch.SetState(false);

	uint32_t _now = millis();

	//Terminal setup ...
	delay(300);
		#ifdef TERMINAL_AVAIL
			Serial.begin(19200);
			Serial.setTimeout(500);
			delay(1000);
			Serial.print("\n\nReboot!!\n\n");
			SerialTimer.DelayedOn(_now,STATUS_MSG_INTERVAL);
		#endif //~TERMINAL_AVAIL
}

//##########################################################
//Main program.
void loop(){

	uint32_t _now = millis();

	delay(300);
	//get system pressure.
	int raw_sig = analogRead(PRESS_SENSOR_PIN);
	int SystemPressure = GetAnalogVal(raw_sig, press_table);

	//get core temp.
	raw_sig = analogRead(EVAP_TEMP_PIN);
	int EvapTemp = GetAnalogVal(raw_sig, temp_table);


		// Evaporater Switch logic ...
			if(
				(EvaporatorTempSwitch.IsInNonBusyState(false)) ||					//Simply not on yet?
				(EvapTemp < EVAP_MIN_TEMP) ||										//Temp too low?
				(EvapTemp < EVAP_ALLOWED_TEMP && EvaporatorTempSwitch.IsBusy())		//Still in recovery?
			){
				EvaporatorTempSwitch.DelayedOn(_now,DE_ICE_DURATION); //off now, then auto-on after a delay.
			}
		// ~ Evaporater Switch logic ...


		// A/C compressor clutch logic ...
		if(SystemPressure > MAX_SYSTEM_PRESSURE){
			CompressorSwitch.DelayedOn(_now,COMPRESSOR_RESTART_DELAY); //off now, then auto-on after a delay.
		}
		else if(SystemPressure < MIN_SYSTEM_PRESSURE){
			CompressorSwitch.SetState(false); //off now and set not busy.
		}
		else if( CompressorSwitch.IsInNonBusyState(false) ){ //no errors or conditions, but still not on?...
			CompressorSwitch.DelayedOn(_now,COMPRESSOR_DEBOUNCE_DELAY);
		}
	// ~ A/C compressor clutch logic


	// Engine fan clutch logic ...
		if(SystemPressure > FAN_ON_PRESSURE){
			EngineFanSwitch.DelayedOff(_now,FAN_OFF_DELAY); //turn on now and set a delay before it can be off again.
		}
	// ~ Engine fan clutch logic


	//Update hardware logic states ...
		bool CompressorState = (CompressorSwitch.GetState() && EvaporatorTempSwitch.GetState()) ? RELAY_ON : RELAY_OFF;
		bool FanState = (EngineFanSwitch.GetState()) ? RELAY_ON : RELAY_OFF;
	// ~ Update hardware pin states


	//report pressure to terminal.
	#ifdef TERMINAL_AVAIL
		if( SerialTimer.GetState() ){
			SerialTimer.DelayedOn(_now,STATUS_MSG_INTERVAL);
			Serial.print("\n System Pressure: " );Serial.print(SystemPressure);
			Serial.print(" Evap Temp(f): " );Serial.print(EvapTemp);
			Serial.print("     Cmprsr sw: " );Serial.print( (CompressorState == RELAY_ON) , HEX );
			Serial.print(" Fan sw: " );Serial.print( (FanState == RELAY_ON), HEX );
			Serial.print(" Evap temp sw: " );Serial.print( EvaporatorTempSwitch.GetState(), HEX );
		}
	#endif //~TERMINAL_AVAIL


	//Send hardware states to pins ...
		digitalWrite(COMPRESSOR_PIN, CompressorState); //apply compressor state.
		digitalWrite(FAN_PIN, FanState); //apply engine fan state.
	// ~ Update hardware pin states


	//  Object animation routines.
		/* Animation routines allow objects to operate separate of main program
		 * code space, simulating a multi-threading environment.
		 */
		CompressorSwitch.animate(_now);
		EngineFanSwitch.animate(_now);
		EvaporatorTempSwitch.animate(_now);
		SerialTimer.animate(_now);
	// ~ Object animation routines

}
//##########################################################