/**
  ******************************************************************************
  * @file    pressure.c 
  * @author  heinrichs weikamp gmbh
  * @date    2014
  * @version V0.0.2
  * @since   20-Oct-2016
  * @brief   
  *           
  @verbatim                 
  ============================================================================== 
                        ##### How to use #####
  ============================================================================== 
	V0.0.2		18-Oct-2016		pressure_calculation_AN520_004_mod_MS5803_30BA__09_2015
	
	@endverbatim
  ******************************************************************************
  * @attention
  *
  * <h2><center>&copy; COPYRIGHT(c) 2016 heinrichs weikamp</center></h2>
  *
  ******************************************************************************
  */ 



/* surface time
 the last 30 minutes will be saved once per minute in a endless loop
 at the beginning of a dive the oldest value will be used
*/
#include "math.h"
#include "scheduler.h"
#include "pressure.h"
#include "i2c.h"
#include "rtc.h"

#define CMD_RESET 0x1E // ADC reset command
#define CMD_ADC_READ 0x00 // ADC read command
#define CMD_ADC_CONV 0x40 // ADC conversion command
#define CMD_ADC_D1 0x00 // ADC D1 conversion
#define CMD_ADC_D2 0x10 // ADC D2 conversion
#define CMD_ADC_256 0x00 // ADC OSR=256
#define CMD_ADC_512 0x02 // ADC OSR=512
#define CMD_ADC_1024 0x04 // ADC OSR=1024
#define CMD_ADC_2048 0x06 // ADC OSR=2056
#define CMD_ADC_4096 0x08 // ADC OSR=4096
#define CMD_PROM_RD 0xA0 // Prom read command

#define PRESSURE_SURFACE_MAX_MBAR		(1030.0f)		/* It is unlikely that pressure at surface is greater than this value => clip to it */
#define PRESSURE_HISTORY_SIZE			(8u)
#define PRESSURE_JUMP_VALID_MBAR	    (500.0f)		/* values are measure several times a second => jumps > 5m very unlikely */

#define PRESSURE_SURFACE_QUE			(30u)			/* history buffer [minutes] for past pressure measurements */

static uint16_t get_ci_by_coef_num(uint8_t coef_num);
//void pressure_calculation_new(void);
//void pressure_calculation_old(void);
static void pressure_calculation_AN520_004_mod_MS5803_30BA__09_2015(void);
static uint8_t crc4(uint16_t n_prom[]);

static HAL_StatusTypeDef pressure_sensor_get_data(void);
static uint32_t get_adc(void);
uint8_t pressureSensorInitSuccess = 0;

static uint16_t C[8] = { 1 };
static uint32_t D1 = 1;
static uint32_t D2 = 1;
static uint8_t n_crc;

static int64_t C5_x_2p8 = 1;
static int64_t C2_x_2p16 = 1;
static int64_t C1_x_2p15 = 1;

/*
short C2plus10000 = -1;
short C3plus200 = -1;
short C4minus250 = -1;
short UT1 = -1;
short C6plus100 = -1;
*/
static float pressure_offset = 0.0;		/* Offset value which may be specified by the user via PC Software */
static float temperature_offset = 0.0;	/* Offset value which may be specified by the user via PC Software */

static float ambient_temperature = 0;
static float ambient_pressure_mbar = 1000.0;
static float surface_pressure_mbar = 1000.0;
static float surface_ring_mbar[PRESSURE_SURFACE_QUE] = { 0 };

static float pressure_history_mbar[PRESSURE_HISTORY_SIZE];

static uint8_t secondCounterSurfaceRing = 0;
static uint8_t avgCount = 0;
static float runningAvg = 0;

float get_temperature(void)
{
	return ambient_temperature;
}

float get_pressure_mbar(void)
{
	return ambient_pressure_mbar;
}

float get_surface_mbar(void)
{
	return surface_pressure_mbar;
}


void init_surface_ring(uint8_t force)
{
	if((surface_ring_mbar[0] == 0) || (force))		/* only initialize once. Keep value in place in case of an i2c recovery */
	{
		secondCounterSurfaceRing = 0;				/* restart calculation */
		avgCount = 0;
		runningAvg = 0;

		for(int i=0; i<PRESSURE_SURFACE_QUE; i++)
			surface_ring_mbar[i] = ambient_pressure_mbar;
		surface_pressure_mbar = ambient_pressure_mbar;
	}
}

void init_pressure_history(void)
{
	for(int i=0; i<PRESSURE_HISTORY_SIZE; i++)
	{
		pressure_history_mbar[i] = 1000.0;
	}
}


void update_surface_pressure(uint8_t call_rhythm_seconds)
{
	static uint8_t writeIndex = 0;		/* Reinitialization will reset all entries to the same value => no need to reinit write index */


	if(is_init_pressure_done())
	{
		runningAvg = (runningAvg * avgCount + ambient_pressure_mbar) / (avgCount +1);
		avgCount++;
		secondCounterSurfaceRing += call_rhythm_seconds;

		if(secondCounterSurfaceRing >= 60)
		{
			if(runningAvg < PRESSURE_SURFACE_MAX_MBAR)
			{
				surface_ring_mbar[writeIndex] = runningAvg;
			}
			else
			{
				surface_ring_mbar[writeIndex] =	PRESSURE_SURFACE_MAX_MBAR;
			}
			writeIndex++; /* the write index is now pointing to the oldest value in the buffer which will be overwritten next time */

			if(writeIndex == PRESSURE_SURFACE_QUE)
			{
				writeIndex = 0;
			}

			surface_pressure_mbar = surface_ring_mbar[writeIndex]; /* 30 minutes old measurement */

			secondCounterSurfaceRing = 0;
			avgCount = 1;	/* use the current value as starting point but restart the weight decrement of the measurements */
		}
	}
}

#ifdef DEMOMODE
float demo_modify_temperature_helper(float bottom_mbar_diff_to_surface)
{
	const float temperature_surface = 31.0;
	const float temperature_bottom = 14.0;

	const float temperature_difference = temperature_bottom - temperature_surface;
	
	// range 0.0 - 1.0
	float position_now = (ambient_pressure_mbar - surface_pressure_mbar) / bottom_mbar_diff_to_surface; 

	if(position_now <= 0)
		return temperature_surface;
	
	if(position_now >= 1)
		return temperature_bottom;

	return temperature_surface + (temperature_difference * position_now);
}


uint32_t demo_modify_temperature_and_pressure(int32_t divetime_in_seconds, uint8_t subseconds, float ceiling_mbar)
{
	
	const float descent_rate = 4000/60;
	const float ascent_rate = 1000/60;
	const uint32_t seconds_descend = (1 * 60) + 30;
	const uint32_t turbo_seconds_at_bottom_start = (0 * 60) + 0;
	const uint32_t seconds_descend_and_bottomtime = seconds_descend + turbo_seconds_at_bottom_start + (2 * 60) + 0;
	uint32_t time_elapsed_in_seconds;
	static float ambient_pressure_mbar_memory = 0;
	static uint32_t time_last_call = 0;
	
	if(divetime_in_seconds <= seconds_descend)
	{
		ambient_pressure_mbar = (divetime_in_seconds * descent_rate) + ((float)(subseconds) * descent_rate) + surface_pressure_mbar;
		ambient_temperature = demo_modify_temperature_helper(descent_rate * seconds_descend);

		time_last_call = divetime_in_seconds;
		return 0;
	}
	else
	if(divetime_in_seconds <= seconds_descend + turbo_seconds_at_bottom_start)
	{
		ambient_pressure_mbar = (seconds_descend * descent_rate) + surface_pressure_mbar;
		ambient_temperature = demo_modify_temperature_helper(descent_rate * seconds_descend);
		ambient_pressure_mbar_memory = ambient_pressure_mbar;
		time_last_call = divetime_in_seconds;
		return turbo_seconds_at_bottom_start;
	}
	else
	if(divetime_in_seconds <= seconds_descend_and_bottomtime)
	{
		ambient_pressure_mbar = (seconds_descend * descent_rate) + surface_pressure_mbar;
		ambient_temperature = demo_modify_temperature_helper(descent_rate * seconds_descend);
		ambient_pressure_mbar_memory = ambient_pressure_mbar;
		time_last_call = divetime_in_seconds;
		return 0;
	}
	else
	{
		time_elapsed_in_seconds = divetime_in_seconds - time_last_call;
		ambient_pressure_mbar = ambient_pressure_mbar_memory - time_elapsed_in_seconds * ascent_rate;

		if(ambient_pressure_mbar < surface_pressure_mbar)
			ambient_pressure_mbar = surface_pressure_mbar;
		else if(ambient_pressure_mbar < ceiling_mbar)
			ambient_pressure_mbar = ceiling_mbar;
		
		ambient_temperature = demo_modify_temperature_helper(descent_rate * seconds_descend);
		ambient_pressure_mbar_memory = ambient_pressure_mbar;
		time_last_call = divetime_in_seconds;
		return 0;
	}
}
#endif

uint8_t is_init_pressure_done(void)
{
	return pressureSensorInitSuccess;
}

uint8_t init_pressure(void)
{
	uint8_t buffer[1];
	buffer[0] = 0x1e;
	uint8_t retValue = 0xFF;
	
	pressureSensorInitSuccess = false;
	init_pressure_history();

/* Send reset request to pressure sensor */
	retValue = I2C_Master_Transmit(  DEVICE_PRESSURE, buffer, 1);
	if(retValue != HAL_OK)
	{
		return (HAL_StatusTypeDef)retValue;
	}
	HAL_Delay(3);
	
	for(uint8_t i=0;i<8;i++)
	{
		C[i] = get_ci_by_coef_num(i);
	}
	n_crc = crc4(C); // no evaluation at the moment hw 151026

	C5_x_2p8  = C[5] * 256;
	C2_x_2p16 = C[2] * 65536;
	C1_x_2p15 = C[1] * 32768;
	
	if(global.I2C_SystemStatus == HAL_OK)
	{
		pressureSensorInitSuccess = 1;
		retValue = pressure_update();

	}
	return retValue;
}


static uint32_t get_adc(void)
{
	uint8_t buffer[1];
	uint8_t resivebuf[4];
	uint32_t answer = 0;

	buffer[0] = 0x00; // Get ADC
	I2C_Master_Transmit( DEVICE_PRESSURE, buffer, 1);
	I2C_Master_Receive(  DEVICE_PRESSURE, resivebuf, 4);
	resivebuf[3] = 0;
	answer = 256*256 *(uint32_t)resivebuf[0]  + 256 * (uint32_t)resivebuf[1] + (uint32_t)resivebuf[2];

	return answer;
}


static uint16_t get_ci_by_coef_num(uint8_t coef_num)
{
	uint8_t resivebuf[2];

	uint8_t cmd = CMD_PROM_RD+coef_num*2; 
	I2C_Master_Transmit( DEVICE_PRESSURE, &cmd, 1);
	I2C_Master_Receive(  DEVICE_PRESSURE, resivebuf, 2);
	return (256*(uint16_t)resivebuf[0]) + (uint16_t)resivebuf[1];
}



uint8_t pressure_update(void)
{
	HAL_StatusTypeDef statusReturn = HAL_TIMEOUT;
	
	statusReturn = pressure_sensor_get_data();
	pressure_calculation();
	return (uint8_t)statusReturn;
}

/* Switch between pressure and temperature measurement with every successful read operation */
void pressure_update_alternating(void)
{
	static uint8_t getTemperature= 0;

	if(getTemperature)
	{
		if(pressure_sensor_get_temperature_raw() == HAL_OK)
		{
			getTemperature = 0;
		}
	}
	else
	{
		if(pressure_sensor_get_pressure_raw() == HAL_OK)
		{
			getTemperature = 1;
		}
	}
	pressure_calculation();
	return;
}

static uint32_t pressure_sensor_get_one_value(uint8_t cmd, HAL_StatusTypeDef *statusReturn)
{
	uint8_t command = CMD_ADC_CONV + cmd;
	HAL_StatusTypeDef statusReturnTemp = HAL_TIMEOUT;
	
	statusReturnTemp = I2C_Master_Transmit( DEVICE_PRESSURE, &command, 1);

	if(statusReturn)
	{
		*statusReturn = statusReturnTemp;
	}
	
	switch (cmd & 0x0f) // wait necessary conversion time
	{
	case CMD_ADC_256 : HAL_Delay(1); break;
	case CMD_ADC_512 : HAL_Delay(3); break;
	case CMD_ADC_1024: HAL_Delay(4); break;
	case CMD_ADC_2048: HAL_Delay(6); break;
	case CMD_ADC_4096: HAL_Delay(10); break;
	}	
	return get_adc();
}


static HAL_StatusTypeDef pressure_sensor_get_data(void)
{
	uint32_t requestedValue = 0;
	HAL_StatusTypeDef statusReturn1 = HAL_TIMEOUT;
	HAL_StatusTypeDef statusReturn2 = HAL_TIMEOUT;
	


	requestedValue = pressure_sensor_get_one_value(CMD_ADC_D2 + CMD_ADC_1024, &statusReturn2);
	if (statusReturn2 == HAL_OK)
	{
		D2 = requestedValue;
	}

	requestedValue = pressure_sensor_get_one_value(CMD_ADC_D1 + CMD_ADC_1024, &statusReturn1);
	if (statusReturn1 == HAL_OK)
	{
		D1 = requestedValue;
	}
	if(statusReturn2 > statusReturn1) // if anything is not HAL_OK (0x00) or worse
		return statusReturn2;
	else
		return statusReturn1;
}


HAL_StatusTypeDef  pressure_sensor_get_pressure_raw(void)
{
	uint32_t requestedValue = 0;
	HAL_StatusTypeDef statusReturn = HAL_TIMEOUT;

	requestedValue = pressure_sensor_get_one_value(CMD_ADC_D1 + CMD_ADC_1024, &statusReturn);
	if (statusReturn == HAL_OK)
	{
		D1 = requestedValue;
	}

	return statusReturn;
}


HAL_StatusTypeDef  pressure_sensor_get_temperature_raw(void)
{
	uint32_t requestedValue = 0;
	HAL_StatusTypeDef statusReturn = HAL_TIMEOUT;

	requestedValue = pressure_sensor_get_one_value(CMD_ADC_D2 + CMD_ADC_1024, &statusReturn);
	if (statusReturn == HAL_OK)
	{
		D2 = requestedValue;
	}
	return statusReturn;
}


void pressure_calculation(void)
{
	if(global.I2C_SystemStatus != HAL_OK)
		return;
	
	pressure_calculation_AN520_004_mod_MS5803_30BA__09_2015();
}

static uint8_t pressure_plausible(float pressurevalue)
{
	static uint8_t pressurewriteindex = 0;
	uint8_t retval = 0;
	uint8_t index;
	float pressure_average = 0;

	for(index = 0; index < PRESSURE_HISTORY_SIZE; index++)
	{
		pressure_average += pressure_history_mbar[index];
	}
	pressure_average /= PRESSURE_HISTORY_SIZE;
	if(pressure_average == 1000.0) /* first pressure calculation */
	{
		if(fabs(pressurevalue - pressure_average) < 11000.0)  /* just in case a reset occur during dive assume value equal < 100m as valid */
		{
			for(index = 0; index < PRESSURE_HISTORY_SIZE; index++)
			{
				pressure_history_mbar[index] = pressurevalue;	/* set history to current value */
				retval = 1;
			}
		}
	}
	else
	{
		if(fabs(pressurevalue - pressure_average) < PRESSURE_JUMP_VALID_MBAR)
		{
			pressure_history_mbar[pressurewriteindex++] = pressurevalue;
			pressurewriteindex &= 0x7;	/* wrap around if necessary */
			retval = 1;
		}
	}

	return retval;
}

static void pressure_calculation_AN520_004_mod_MS5803_30BA__09_2015(void)
{
	static float runningAvg = 0;
	static uint8_t avgCnt = 0;

	uint32_t local_D1; // ADC value of the pressure conversion
	uint32_t local_D2; // ADC value of the temperature conversion
	int32_t local_Px10; // compensated pressure value
	int32_t local_Tx100; // compensated temperature value
	int64_t local_dT; // int32_t, difference between actual and measured temperature
	int64_t local_OFF; // offset at actual temperature
	int64_t local_SENS; // sensitivity at actual temperature

	float calc_pressure;

	int64_t T2;
	int64_t OFF2;
	int64_t SENS2;

	local_D1 = D1;
	local_D2 = D2;

	local_dT 		= ((int64_t)local_D2) - ((int64_t)C[5]) * 256; //pow(2,8);
	local_OFF 	= ((int64_t)C[2]) * 65536 + local_dT * ((int64_t)C[4]) / 128; // pow(2,16), pow(2,7)
	local_SENS 	= ((int64_t)C[1]) * 32768 + local_dT * ((int64_t)C[3]) / 256; // pow(2,15), pow(2,8)

	local_Tx100 = (int32_t)(2000 + (local_dT * ((int64_t)C[6])) / 8388608);// pow(2,23)


	if(local_Tx100 < 2000) // low temperature
	{
		T2  = 3 * local_dT;
		T2 *= local_dT;
		T2 /= 8589934592;

		OFF2 = ((int64_t)local_Tx100) - 2000;
		OFF2 *= OFF2;
		OFF2 *= 3;
		OFF2 /= 2;
		
		SENS2 = ((int64_t)local_Tx100) - 2000;
		SENS2 *= SENS2;
		SENS2 *= 5;
		SENS2 /= 8;

		local_Tx100 -= (int32_t)T2;
		local_OFF 	-= OFF2;
		local_SENS 	-= SENS2;
	}
	else
	{
		T2  = 7 * local_dT;
		T2 *= local_dT;
		T2 /= 137438953472;

		OFF2 = ((int64_t)local_Tx100) - 2000;
		OFF2 *= OFF2;
		OFF2 /= 16;
		
		local_Tx100 -= (int32_t)T2;
		local_OFF 	-= OFF2;
	}
	
	local_Px10 = (int32_t)(
							(((int64_t)((local_D1 * local_SENS) / 2097152)) - local_OFF)
								/  8192 );//     )) / 10; // pow(2,21), pow(2,13)

	ambient_temperature = ((float)local_Tx100) / 100;
	ambient_temperature	+= temperature_offset;

	calc_pressure = ((float)local_Px10) / 10;
	calc_pressure += pressure_offset;

	if(pressure_plausible(calc_pressure))
	{
		runningAvg = (avgCnt * runningAvg + calc_pressure) / (avgCnt + 1);
		if (avgCnt < 10)	/* build an average considering the last measurements to have a weight "1 of 10" */
		{					/* Main reason for this is the jitter of up to +-10 HPa in surface mode which is caused */
			avgCnt++;		/* by the measurement range of the sensor which is focused on under water pressure measurement */
		}
		ambient_pressure_mbar = runningAvg;
	}
}


/*
void pressure_calculation_new(void)
{
#define POW2_8	(256)
#define POW2_17	(131072)
#define POW2_6	(64)
#define POW2_16	(65536)
#define POW2_7	(128)
#define POW2_23	(8388608)
#define POW2_21	(2097152)
#define POW2_15	(32768)
#define POW2_13	(8192)
#define POW2_37	(137438953472)
#define POW2_4	(16)
#define POW2_33	(8589934592)
#define POW2_3	(8)
	
	int32_t	P; // compensated pressure value
	int32_t T; // compensated temperature value
	int32_t dT; // difference between actual and measured temperature
	int64_t OFF; // offset at actual temperature
	int64_t SENS;

	int32_t T2;
	int64_t OFF2;
	int64_t SENS2;
	
	dT 		= ((int32_t)D2) - ((int32_t)C[5]) * POW2_8;
	OFF 	= ((int64_t)C[2]) * POW2_16 + ((int64_t)dT) * ((int64_t)C[4]) / POW2_7;
	SENS 	= ((int64_t)C[1]) * POW2_15 + ((int64_t)dT) * ((int64_t)C[3]) / POW2_8;

	T	= 2000 + (dT * ((int32_t)C[6])) / POW2_23;


if(T < 2000) // low temperature
	{
		T2 = 3 * dT * dT;
		T2 /= POW2_33;
		OFF2 = ((int64_t)T) - 2000;
		OFF2 *= OFF2;
		OFF2 *= 3;
		OFF2 /= 2;
		SENS2 = ((int64_t)T) - 2000;
		SENS2 *= SENS2;
		SENS2 *= 5;
		SENS2 /= POW2_3;
	}
	else // high temperature
	{
		T2 = 7 * dT * dT;
		T2 /= POW2_37;
		OFF2 = ((int64_t)T) - 2000;
		OFF2 *= OFF2;
		OFF2 /= POW2_4;
		SENS2 = 0;
	}

	T = T - T2;
	OFF = OFF - OFF2;
	SENS = SENS - SENS2;
	
	P = (int32_t)(((((int64_t)D1) * SENS) / POW2_21 - OFF) / POW2_13);
	
	ambient_temperature 	= ((float)T) / 100;
	ambient_pressure_mbar	= ((float)P) / 10;
}
*/

/*
void pressure_calculation_old(void) {
	//
	double ambient_temperature_centigrad = 0;
	double ambient_pressure_decimbar = 0;
	
	// static for debug
	static int64_t dt = 0;
	static int64_t temp = 0;
	static int64_t ms_off = 0;
	static int64_t sens = 0;
	//
	static int64_t ms_off2 = 0;
	static int64_t sens2 = 0;
	static int64_t t2 = 0;

	if((D2 == 0) || (D1 == 0))
		return;
	//

	// dT = D2 - C[5] * POW2_8;
	// T	= 2000 + (dT * C[6]) / POW2_23;
	dt = (int64_t)D2 - C5_x_2p8;
	//temp ; // in 10 milliGrad Celcius
	ambient_temperature_centigrad = 2000 + dt * C[6] / 8388608;
	

	if(ambient_temperature_centigrad < 2000) // low temperature
		{
			t2 = 3 * dt;
			t2 *= dt;
			t2 /= 8589934592;
			ms_off2 = ambient_temperature_centigrad - 2000;
			ms_off2 *= ms_off2;
			sens2 = ms_off2;
			ms_off2 *= 3;
			ms_off2 /= 2;
			sens2 *= 5;
			sens2 /= 8;
		}
		else // high temperature
		{
			t2 = 7 * dt;
			t2 *= dt;
			t2 /= 137438953472;
			ms_off2 = ambient_temperature_centigrad - 2000;
			ms_off2 *= ms_off2;
			ms_off2 /= 16;
			sens2 = 0;
		}
	
	
	//

	// pressure
	// OFF 	= C[2] * POW2_16 + dT * C[4] / POW2_7;
	// SENS = C[1] * POW2_15 + dT * C[3] / POW2_8;
	ms_off =  C[4] * dt;
	ms_off /= 128;
	ms_off += C2_x_2p16;
	//
	sens =  C[3] * dt;
	sens /= 256;
	sens += C1_x_2p15;

	// 2nd order correction
	ambient_temperature_centigrad -= t2;
	ms_off -= ms_off2;
	sens -= sens2;

	ambient_temperature = ambient_temperature_centigrad / 100;
		// P = (D1 * SENS / POW2_21 - OFF) / POW2_13;
	temp = D1 * sens;
	temp /= 2097152;
	temp -= ms_off;
	temp /= 8192;
	ambient_pressure_decimbar = temp; // to float/double
	ambient_pressure_mbar = ambient_pressure_decimbar / 10;
}
*/


/* taken from AN520 by meas-spec.com dated 9. Aug. 2011
 * short and int are both 16bit according to AVR/GCC google results
 */
static uint8_t crc4(uint16_t n_prom[])
{
uint16_t cnt; // simple counter
uint16_t n_rem; // crc reminder
uint16_t crc_read; // original value of the crc
uint8_t n_bit;
n_rem = 0x00;
crc_read=n_prom[7]; //save read CRC
n_prom[7]=(0xFF00 & (n_prom[7])); //CRC byte is replaced by 0
for (cnt = 0; cnt < 16; cnt++) // operation is performed on bytes
{ // choose LSB or MSB
if (cnt%2==1) n_rem ^= (uint16_t) ((n_prom[cnt>>1]) & 0x00FF);
else n_rem ^= (uint16_t) (n_prom[cnt>>1]>>8);
for (n_bit = 8; n_bit > 0; n_bit--)
{
if (n_rem & (0x8000))
{
n_rem = (n_rem << 1) ^ 0x3000;
}
else
{
n_rem = (n_rem << 1);
}
}
}
n_rem= (0x000F & (n_rem >> 12)); // // final 4-bit reminder is CRC code
n_prom[7]=crc_read; // restore the crc_read to its original place
return (n_rem ^ 0x00);
}
/*
void test_calculation(void)
{
	C1 = 29112;
	C2 = 26814;
	C3 = 19125;
	C4 = 17865;
	C5 = 32057;
	C6 = 31305;
	
	C2_x_2p16 = C2 * 65536;
	C1_x_2p15 = C1 * 32768;
	
	D1 = 4944364;
	D2 = 8198974;	
		pressure_calculation() ;
};
*/
void pressure_set_offset (float pressureOffset, float temperatureOffset)
{
	if(pressure_offset != pressureOffset)				/* we received a new value => reinit surface que */
	{
		ambient_pressure_mbar -= pressure_offset;		/* revert old value */
		ambient_pressure_mbar += pressureOffset;		/* apply new offset */
		init_surface_ring(1);
	}

	pressure_offset = pressureOffset;
	temperature_offset = temperatureOffset;
}