/**+
−
  ******************************************************************************+
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  * @file    pressure.c +
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  * @author  heinrichs weikamp gmbh+
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  * @date    2014+
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  * @version V0.0.2+
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  * @since   20-Oct-2016+
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  * @brief   +
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  *           +
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  @verbatim                 +
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  ============================================================================== +
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                        ##### How to use #####+
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  ============================================================================== +
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	V0.0.2		18-Oct-2016		pressure_calculation_AN520_004_mod_MS5803_30BA__09_2015+
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	+
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	@endverbatim+
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  ******************************************************************************+
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  * @attention+
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  *+
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  * <h2><center>&copy; COPYRIGHT(c) 2016 heinrichs weikamp</center></h2>+
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  *+
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  ******************************************************************************+
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  */ +
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+
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+
−
+
−
/* 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+
−
*/+
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#include "math.h"+
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#include "scheduler.h"+
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#include "pressure.h"+
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#include "i2c.h"+
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#include "rtc.h"+
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+
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#define CMD_RESET 0x1E // ADC reset command+
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#define CMD_ADC_READ 0x00 // ADC read command+
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#define CMD_ADC_CONV 0x40 // ADC conversion command+
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#define CMD_ADC_D1 0x00 // ADC D1 conversion+
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#define CMD_ADC_D2 0x10 // ADC D2 conversion+
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#define CMD_ADC_256 0x00 // ADC OSR=256+
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#define CMD_ADC_512 0x02 // ADC OSR=512+
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#define CMD_ADC_1024 0x04 // ADC OSR=1024+
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#define CMD_ADC_2048 0x06 // ADC OSR=2056+
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#define CMD_ADC_4096 0x08 // ADC OSR=4096+
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#define CMD_PROM_RD 0xA0 // Prom read command+
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+
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/* remove comment to use a predefined profile for pressure changes instead of real world data */+
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/* #define SIMULATE_PRESSURE */+
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+
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#define PRESSURE_SURFACE_MAX_MBAR			(1030.0f)		/* It is unlikely that pressure at surface is greater than this value => clip to it */+
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#define PRESSURE_HISTORY_SIZE				(8u)+
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#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 */+
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#define PRESSURE_SURFACE_EVA_WINDOW				(15u)			/* Number of entries evaluated during instability test. Used to avoid detection while dive enters water */+
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#define PRESSURE_SURFACE_STABLE_LIMIT			(10u)			/* Define pressure as stable if delta (mBar) is below this value */+
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#define PRESSURE_SURFACE_DETECT_STABLE_CNT		(5u)			/* Event count to detect stable condition */+
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#define PRESSURE_SURFACE_UNSTABLE_LIMIT			(50u)			/* Define pressure as not stable if delta (mBar) is larger than this value */+
−
#define PRESSURE_SURFACE_DETECT_UNSTABLE_CNT	(3u)			/* Event count to detect unstable condition */+
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+
−
+
−
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);+
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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;+
−
+
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static uint16_t C[8] = { 1 };+
−
static uint32_t D1 = 1;+
−
static uint32_t D2 = 1;+
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static uint8_t n_crc;+
−
+
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static int64_t C5_x_2p8 = 1;+
−
static int64_t C2_x_2p16 = 1;+
−
static int64_t C1_x_2p15 = 1;+
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+
−
/*+
−
short C2plus10000 = -1;+
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short C3plus200 = -1;+
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short C4minus250 = -1;+
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short UT1 = -1;+
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short C6plus100 = -1;+
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*/+
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static float pressure_offset = 0.0;		/* Offset value which may be specified by the user via PC Software */+
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static float temperature_offset = 0.0;	/* Offset value which may be specified by the user via PC Software */+
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+
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static float ambient_temperature = 0;+
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static float ambient_pressure_mbar = 1000.0;+
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static float surface_pressure_mbar = 1000.0;+
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static float surface_ring_mbar[PRESSURE_SURFACE_QUE] = { 0 };+
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+
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static uint8_t surface_pressure_writeIndex = 0;+
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static float surface_pressure_stable_value = 0;+
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static uint8_t surface_pressure_stable = 0;+
−
+
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static float pressure_history_mbar[PRESSURE_HISTORY_SIZE];+
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+
−
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;+
−
}+
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+
−
+
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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 */+
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		avgCount = 0;+
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		runningAvg = 0;+
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+
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		for(int i=0; i<PRESSURE_SURFACE_QUE; i++)+
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			surface_ring_mbar[i] = ambient_pressure_mbar;+
−
		surface_pressure_mbar = ambient_pressure_mbar;+
−
		surface_pressure_writeIndex = 0;			/* index of the oldest value in the ring buffer */+
−
	}+
−
}+
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+
−
void init_pressure_history(void)+
−
{+
−
	for(int i=0; i<PRESSURE_HISTORY_SIZE; i++)+
−
	{+
−
		pressure_history_mbar[i] = 1000.0;+
−
	}+
−
}+
−
+
−
uint8_t is_surface_pressure_stable(void)+
−
{+
−
	return surface_pressure_stable;+
−
}+
−
+
−
float set_last_surface_pressure_stable(void)+
−
{+
−
	surface_pressure_mbar = surface_pressure_stable_value;+
−
	return surface_pressure_stable_value;+
−
}+
−
+
−
/* iterate backward through the history memory and evaluate the changes pressure changes during the last 30 minutes */+
−
void evaluate_surface_pressure()+
−
{+
−
	uint8_t index;+
−
	float lastvalue;+
−
	uint8_t stablecnt = 0;+
−
	uint8_t unstablecnt = 0;+
−
	uint8_t EvaluationWindow = PRESSURE_SURFACE_QUE - PRESSURE_SURFACE_EVA_WINDOW;	/* do not use the latest 15 values to avoid unstable condition due to something like fin handling */+
−
	uint8_t EvaluatedValues = 0;+
−
+
−
	lastvalue = surface_ring_mbar[surface_pressure_writeIndex];+
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	surface_pressure_stable_value = surface_ring_mbar[surface_pressure_writeIndex]; /* default: if no stable value is found return the oldest value */+
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	index = surface_pressure_writeIndex;+
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	surface_pressure_stable = 1;+
−
+
−
	if(index == 0)+
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	{+
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		index = PRESSURE_SURFACE_QUE - 1;+
−
	}+
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	else+
−
	{+
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		index = index - 1;+
−
	}+
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	do+
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	{+
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		if((EvaluatedValues < EvaluationWindow) &&+
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			(fabs(surface_pressure_stable_value - surface_ring_mbar[index]) > PRESSURE_SURFACE_UNSTABLE_LIMIT)) /* unusual change during last 30 minutes */+
−
		{+
−
			unstablecnt++;+
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			if(unstablecnt > PRESSURE_SURFACE_DETECT_UNSTABLE_CNT)+
−
			{+
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				surface_pressure_stable = 0;+
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			}+
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		}+
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	/* search for a value which does not change for several iterations */+
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		if (fabs(lastvalue - surface_ring_mbar[index]) < PRESSURE_SURFACE_STABLE_LIMIT)+
−
		{+
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			stablecnt++;+
−
		}+
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		else+
−
		{+
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			stablecnt = 0;+
−
		}+
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		if ((stablecnt >= PRESSURE_SURFACE_DETECT_STABLE_CNT) && (surface_pressure_stable == 0)&&(surface_pressure_stable_value == surface_ring_mbar[surface_pressure_writeIndex])) /* pressure is unstable => search for new stable value */+
−
		{+
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			surface_pressure_stable_value = surface_ring_mbar[index];+
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			unstablecnt = 0;+
−
		}+
−
+
−
		lastvalue = surface_ring_mbar[index];+
−
+
−
		if(index == 0)+
−
		{+
−
			index = PRESSURE_SURFACE_QUE - 1;+
−
		}+
−
		else+
−
		{+
−
			index = index - 1;+
−
		}+
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		EvaluatedValues++;+
−
	} while (index != surface_pressure_writeIndex);+
−
}+
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void update_surface_pressure(uint8_t call_rhythm_seconds)+
−
{+
−
+
−
+
−
	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)+
−
			{+
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				surface_ring_mbar[surface_pressure_writeIndex] = runningAvg;+
−
			}+
−
			else+
−
			{+
−
				surface_ring_mbar[surface_pressure_writeIndex] =	PRESSURE_SURFACE_MAX_MBAR;+
−
			}+
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			surface_pressure_writeIndex++; /* the write index is now pointing to the oldest value in the buffer which will be overwritten next time */+
−
+
−
			if(surface_pressure_writeIndex == PRESSURE_SURFACE_QUE)+
−
			{+
−
				surface_pressure_writeIndex = 0;+
−
			}+
−
+
−
			surface_pressure_mbar = surface_ring_mbar[surface_pressure_writeIndex]; /* 30 minutes old measurement */+
−
+
−
			secondCounterSurfaceRing = 0;+
−
			avgCount = 1;	/* use the current value as starting point but restart the weight decrement of the measurements */+
−
		}+
−
		evaluate_surface_pressure();+
−
	}+
−
}+
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+
−
#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);+
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		ambient_pressure_mbar_memory = ambient_pressure_mbar;+
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		time_last_call = divetime_in_seconds;+
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		return 0;+
−
	}+
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}+
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#endif+
−
+
−
uint8_t is_init_pressure_done(void)+
−
{+
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	return pressureSensorInitSuccess;+
−
}+
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+
−
uint8_t init_pressure(void)+
−
{+
−
	uint8_t buffer[1];+
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	buffer[0] = 0x1e;+
−
	uint8_t retValue = 0xFF;+
−
	+
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	pressureSensorInitSuccess = false;+
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	init_pressure_history();+
−
+
−
/* Send reset request to pressure sensor */+
−
	retValue = I2C_Master_Transmit(  DEVICE_PRESSURE, buffer, 1);+
−
	if(retValue != HAL_OK)+
−
	{+
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		return (HAL_StatusTypeDef)retValue;+
−
	}+
−
	HAL_Delay(3);+
−
	+
−
	for(uint8_t i=0;i<8;i++)+
−
	{+
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		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;+
−
}+
−
+
−
+
−
#ifdef SIMULATE_PRESSURE+
−
void pressure_simulation()+
−
{+
−
	static uint32_t tickstart = 0;+
−
	static float pressure_sim_mbar = 0;+
−
	static uint32_t passedSecond = 0;+
−
	static uint32_t secondtick = 0;+
−
+
−
	uint32_t lasttick = 0;+
−
+
−
+
−
+
−
	if( tickstart == 0)+
−
	{+
−
		tickstart = HAL_GetTick(); /* init time stamp */+
−
		secondtick = tickstart;+
−
		pressure_sim_mbar = 1000;+
−
	}+
−
+
−
	lasttick = HAL_GetTick();+
−
	if(time_elapsed_ms(secondtick,lasttick) > 1000) /* one second passed since last tick */+
−
	{+
−
		secondtick = lasttick;+
−
		passedSecond++;+
−
+
−
#ifdef DIVE_AFTER_LANDING+
−
		if(passedSecond < 10) pressure_sim_mbar = 1000.0;	 /* stay stable for 10 seconds */+
−
		else if(passedSecond < 300) pressure_sim_mbar -= 1.0; /* decrease pressure in 5 minutes target 770mbar => delta 330 */+
−
		else if(passedSecond < 900) pressure_sim_mbar += 0.0;	/*stay stable 10 minutes*/+
−
		else if(passedSecond < 1500) pressure_sim_mbar += 0.5;	/* return to 1 bar in 10 Minutes*/+
−
		else if(passedSecond < 1800) pressure_sim_mbar += 0.0;	/* 5 minutes break */+
−
		else if(passedSecond < 2000) pressure_sim_mbar += 10.0; /* start dive */+
−
		else if(passedSecond < 2300) pressure_sim_mbar += 0.0;  /* stay on depth */+
−
		else if(passedSecond < 2500) pressure_sim_mbar -= 10.0; /* return to surface */+
−
		else pressure_sim_mbar = 1000.0;					/* final state */+
−
#else	/* short dive */+
−
		if(passedSecond < 10) pressure_sim_mbar = 1000.0;	   /* stay stable for 10 seconds */+
−
		else if(passedSecond < 180) pressure_sim_mbar += 10.0; /* Start dive */+
−
		else if(passedSecond < 300) pressure_sim_mbar += 0.0;	/*stay on depth*/+
−
		else if(passedSecond < 460) pressure_sim_mbar -= 10.0;	/* return to surface */+
−
		else if(passedSecond < 600) pressure_sim_mbar += 0.0;   /* stay */+
−
		else if(passedSecond < 610) pressure_sim_mbar = 1000.0; /* get ready for second dive */+
−
		else if(passedSecond < 780) pressure_sim_mbar += 10.0; /* Start dive */+
−
		else if(passedSecond < 900) pressure_sim_mbar += 0.0;	/*stay on depth*/+
−
		else if(passedSecond < 1060) pressure_sim_mbar -= 10.0;	/* return to surface */+
−
		else if(passedSecond < 1200) pressure_sim_mbar += 0.0;   /* stay */+
−
		else pressure_sim_mbar = 1000.0;					/* final state */+
−
#endif+
−
	}+
−
+
−
+
−
	ambient_pressure_mbar = pressure_sim_mbar;+
−
	ambient_temperature = 25.0;+
−
	return;+
−
}+
−
+
−
#endif+
−
+
−
void pressure_calculation(void)+
−
{+
−
	if(global.I2C_SystemStatus != HAL_OK)+
−
		return;+
−
+
−
#ifdef SIMULATE_PRESSURE+
−
	pressure_simulation();+
−
#else+
−
	pressure_calculation_AN520_004_mod_MS5803_30BA__09_2015();+
−
#endif+
−
}+
−
+
−
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;+
−
	}+
−
}+
−
+
−
+
−
/* 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;+
−
}+
−
+
−
+
−