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Added pressure compensation to CO2 detection: A pressure compensation is needed if the ExplorIR shall be used under extended pressure conditions. The procedure recommended by the application note has been integrated. To keep things simple the focus of the CO2 measurement is not the precision, as it is needed for the decompression calculation, but the indication of a critical increase of CO2 in the breathing loop. That's why only a lookup table with 1000ppm steps has been implemented instead of calculating the polynom for every measurement.
author Ideenmodellierer
date Sun, 05 Mar 2023 22:06:47 +0100
parents 7e84ae1513b6
children 4a28402e4aca
line wrap: on
line source

/**
  ******************************************************************************
  * @file    externalInterface.c
  * @author  heinrichs weikamp gmbh
  * @version V0.0.1
  * @date    07-Nov-2020
  * @brief   Interface functionality to proceed external analog signal via i2c connection
  *
  @verbatim
  ==============================================================================
                ##### stm32f4xx_hal_i2c.c modification #####
  ==============================================================================
	The LTC2942 requires an repeated start condition without stop condition
	for data reception.

  @endverbatim
  ******************************************************************************
  * @attention
  *
  * <h2><center>&copy; COPYRIGHT(c) 2014 heinrichs weikamp</center></h2>
  *
  ******************************************************************************
  */
/* Includes ------------------------------------------------------------------*/

#include <math.h>
#include <string.h>
#include "i2c.h"
#include "externalInterface.h"
#include "scheduler.h"
#include "uart.h"
#include "data_exchange.h"
#include "pressure.h"

extern SGlobal global;
extern UART_HandleTypeDef huart1;

#define ADC_ANSWER_LENGTH	(5u)		/* 3424 will provide addr + 4 data bytes */
#define ADC_TIMEOUT			(10u)		/* conversion stuck for unknown reason => restart */
#define ADC_REF_VOLTAGE_MV	(2048.0f)	/* reference voltage of MPC3424*/

#define ADC_START_CONVERSION		(0x80)
#define ADC_GAIN_4					(0x02)
#define ADC_GAIN_4_VALUE			(4.0f)
#define ADC_GAIN_8					(0x03)
#define ADC_GAIN_8_VALUE			(8.0f)
#define ADC_RESOLUTION_16BIT		(0x08)
#define ADC_RESOLUTION_16BIT_VALUE	(16u)
#define ADC_RESOLUTION_18BIT		(0x0C)
#define ADC_RESOLUTION_18BIT_VALUE	(18u)

#define ANSWER_CONFBYTE_INDEX		(4u)

#define LOOKUP_CO2_CORR_TABLE_SCALE	(1000u)
#define LOOKUP_CO2_CORR_TABLE_MAX	(30000u)

static uint8_t activeChannel = 0;			/* channel which is in request */
static uint8_t recBuf[ADC_ANSWER_LENGTH];
static uint8_t timeoutCnt = 0;
static uint8_t externalInterfacePresent = 0;

float externalChannel_mV[MAX_ADC_CHANNEL];
static uint8_t  externalV33_On = 0;
static uint8_t  externalADC_On = 0;
static uint8_t  externalUART_Protocol = 0;
static uint16_t externalCO2Value;
static uint16_t externalCO2SignalStrength;
static uint16_t  externalCO2Status = 0;

static uint8_t sensorDataId = 0;
static SSensorDataDiveO2 sensorDataDiveO2;
static externalInterfaceAutoDetect_t externalAutoDetect = DETECTION_OFF;
static externalInterfaceSensorType SensorMap[EXT_INTERFACE_SENSOR_CNT] ={ SENSOR_OPTIC, SENSOR_OPTIC, SENSOR_OPTIC, SENSOR_NONE, SENSOR_NONE};
static externalInterfaceSensorType tmpSensorMap[EXT_INTERFACE_SENSOR_CNT];
static externalInterfaceSensorType MasterSensorMap[EXT_INTERFACE_SENSOR_CNT];

static float LookupCO2PressureCorrection[LOOKUP_CO2_CORR_TABLE_MAX / LOOKUP_CO2_CORR_TABLE_SCALE];		/* lookup table for pressure compensation values */


void externalInterface_Init(void)
{
	uint16_t index;
	uint16_t coeff;
	activeChannel = 0;
	timeoutCnt = 0;
	externalInterfacePresent = 0;
	if(externalInterface_StartConversion(activeChannel) == HAL_OK)
	{
		externalInterfacePresent = 1;
		global.deviceDataSendToMaster.hw_Info.extADC = 1;
	}
	global.deviceDataSendToMaster.hw_Info.checkADC = 1;

/* Create a lookup table based on GSS application note AN001: PRESSURE COMPENSATION OF A CO2 SENSOR */
/* The main purpose of the sensor in the dive application is to be a warning indicator */
/* => no exact values necessary => a lookup table with 50 entries should be sufficient */
	LookupCO2PressureCorrection [0] = -0.0014;
	for(index = 1; index < (LOOKUP_CO2_CORR_TABLE_MAX / LOOKUP_CO2_CORR_TABLE_SCALE); index++)
	{
		coeff = index * LOOKUP_CO2_CORR_TABLE_SCALE;
		LookupCO2PressureCorrection[index] = 2.811*pow(10,-38)*pow(coeff,6)- 9.817*pow(10,-32)*pow(coeff,5)+1.304*pow(10,-25)*pow(coeff,4)-8.216*pow(10,-20)*pow(coeff,3)+2.311*pow(10,-14)*pow(coeff,2) - 2.195*pow(10,-9)*coeff - 1.471*pow(10,-3);
	}
	externalInterface_InitDatastruct();
}

void externalInterface_InitDatastruct(void)
{
	uint8_t index = 0;
	/* init data values */
	externalV33_On = 0;
	externalCO2Value = 0;
	externalCO2SignalStrength = 0;
	externalCO2Status = 0;
	externalAutoDetect = DETECTION_OFF;

	for(index = 0; index < MAX_ADC_CHANNEL; index++)
	{
		externalChannel_mV[index] = 0.0;
	}
}


uint8_t externalInterface_StartConversion(uint8_t channel)
{
	uint8_t retval = 0;
	uint8_t confByte = 0;

	if(channel < MAX_ADC_CHANNEL)
	{
		confByte = ADC_START_CONVERSION | ADC_RESOLUTION_16BIT | ADC_GAIN_8;
		confByte |= channel << 5;
		retval = I2C_Master_Transmit(DEVICE_EXTERNAL_ADC, &confByte, 1);
	}
	return retval;
}

/* Check if conversion is done and trigger measurement of next channel */
uint8_t externalInterface_ReadAndSwitch()
{
	uint8_t retval = EXTERNAL_ADC_NO_DATA;
	uint8_t nextChannel;
	uint8_t* psensorMap = externalInterface_GetSensorMapPointer(0);

	if(externalADC_On)
	{
		if(I2C_Master_Receive(DEVICE_EXTERNAL_ADC, recBuf, ADC_ANSWER_LENGTH) == HAL_OK)
		{
			if((recBuf[ANSWER_CONFBYTE_INDEX] & ADC_START_CONVERSION) == 0)		/* !ready set => received data contains new value */
			{
				retval = activeChannel;										/* return channel number providing new data */
				nextChannel = activeChannel + 1;
				if(nextChannel == MAX_ADC_CHANNEL)
				{
					nextChannel = 0;
				}

				while((psensorMap[nextChannel] != SENSOR_ANALOG) && (nextChannel != activeChannel))
				{
					if(nextChannel == MAX_ADC_CHANNEL)
					{
						nextChannel = 0;
					}
					else
					{
						nextChannel++;
					}
				}

				activeChannel = nextChannel;
				externalInterface_StartConversion(activeChannel);
				timeoutCnt = 0;
			}
			else
			{
				if(timeoutCnt++ >= ADC_TIMEOUT)
				{
					externalInterface_StartConversion(activeChannel);
					timeoutCnt = 0;
				}
			}
		}
		else		/* take also i2c bus disturb into account */
		{
			if(timeoutCnt++ >= ADC_TIMEOUT)
			{
				externalInterface_StartConversion(activeChannel);
				timeoutCnt = 0;
			}
		}
	}
	return retval;
}
float externalInterface_CalculateADCValue(uint8_t channel)
{
	int32_t rawvalue = 0;
	float retValue = 0.0;
	if(channel < MAX_ADC_CHANNEL)
	{

		rawvalue = ((recBuf[0] << 16) | (recBuf[1] << 8) | (recBuf[2]));

		switch(recBuf[3] & 0x0C)			/* confbyte => Resolution bits*/
		{
			case ADC_RESOLUTION_16BIT:		rawvalue = rawvalue >> 8;										/* only 2 databytes received shift out confbyte*/
											if(rawvalue & (0x1 << (ADC_RESOLUTION_16BIT_VALUE-1)))			/* MSB set => negative number */
											{
												rawvalue |= 0xFFFF0000; 	/* set MSB for int32 */
											}
											else
											{
												rawvalue &= 0x0000FFFF;
											}
											externalChannel_mV[channel] = ADC_REF_VOLTAGE_MV * 2.0 / (float) pow(2,ADC_RESOLUTION_16BIT_VALUE);	/* calculate bit resolution */
				break;
			case ADC_RESOLUTION_18BIT:		if(rawvalue & (0x1 << (ADC_RESOLUTION_18BIT_VALUE-1)))			/* MSB set => negative number */
											{
												rawvalue |= 0xFFFE0000; 	/* set MSB for int32 */
											}
											externalChannel_mV[channel] = ADC_REF_VOLTAGE_MV * 2.0 / (float) pow(2,ADC_RESOLUTION_18BIT_VALUE);	/* calculate bit resolution */
							break;
			default: rawvalue = 0;
				break;
		}
		externalChannel_mV[channel] = externalChannel_mV[channel] * rawvalue / ADC_GAIN_8_VALUE;
		retValue = externalChannel_mV[channel];
	}
	return retValue;
}
float getExternalInterfaceChannel(uint8_t channel)
{
	float retval = 0;

	if(channel < MAX_ADC_CHANNEL)
	{
		retval = externalChannel_mV[channel];
	}
	return retval;
}

uint8_t setExternalInterfaceChannel(uint8_t channel, float value)
{
	uint8_t retval = 0;

	if(channel < MAX_ADC_CHANNEL)
	{
		externalChannel_mV[channel] = value;
		retval = 1;
	}
	return retval;
}

void externalInterface_InitPower33(void)
{
	GPIO_InitTypeDef   GPIO_InitStructure;

	GPIO_InitStructure.Pin = GPIO_PIN_7;
	GPIO_InitStructure.Mode = GPIO_MODE_OUTPUT_PP;
	GPIO_InitStructure.Pull = GPIO_PULLUP;
	GPIO_InitStructure.Speed = GPIO_SPEED_LOW;
	HAL_GPIO_Init(GPIOC, &GPIO_InitStructure);
	HAL_GPIO_WritePin(GPIOC,GPIO_PIN_7,GPIO_PIN_SET);
}


uint8_t externalInterface_isEnabledPower33()
{
	return externalV33_On;
}

uint8_t externalInterface_isEnabledADC()
{
	return externalADC_On;
}

uint8_t externalInterface_GetUARTProtocol()
{
	return externalUART_Protocol;
}

void externalInterface_SwitchPower33(uint8_t state)
{
	if(state != externalV33_On)
	{
		if(state)
		{
			HAL_GPIO_WritePin(GPIOC,GPIO_PIN_7,GPIO_PIN_RESET);
			externalV33_On = 1;
		}
		else
		{
			if(externalAutoDetect == DETECTION_OFF)
			{
				HAL_GPIO_WritePin(GPIOC,GPIO_PIN_7,GPIO_PIN_SET);
				externalV33_On = 0;
				externalInterface_SetCO2Value(0);
				externalInterface_SetCO2SignalStrength(0);
			}
		}
	}
}
void externalInterface_SwitchADC(uint8_t state)
{
	uint8_t loop = 0;
	if((state) && (externalInterfacePresent))
	{
		if(externalADC_On == 0)
		{
			activeChannel = 0;
			externalInterface_StartConversion(activeChannel);
			externalADC_On = 1;
		}
	}
	else
	{
		if(externalAutoDetect == DETECTION_OFF)			/* block deactivation requests if auto detection is active */
		{
			externalADC_On = 0;
			for(loop = 0; loop < MAX_ADC_CHANNEL; loop++)
			{
				externalChannel_mV[loop] = 0;
			}
		}
	}
}

void externalInterface_SwitchUART(uint8_t protocol)
{
	switch(protocol)
	{
		case 0:
		case (EXT_INTERFACE_UART_CO2 >> 8):
		case (EXT_INTERFACE_UART_O2 >> 8):
		case (EXT_INTERFACE_UART_SENTINEL >> 8):
				if((externalAutoDetect <= DETECTION_START) || ((protocol == EXT_INTERFACE_UART_O2 >> 8) && (externalAutoDetect == DETECTION_DIGO2))
#ifdef ENABLE_CO2_SUPPORT
															|| ((protocol == EXT_INTERFACE_UART_CO2 >> 8) && (externalAutoDetect == DETECTION_CO2))
#endif
#ifdef ENABLE_SENTINEL_MODE
														   || ((protocol == EXT_INTERFACE_UART_SENTINEL >> 8) && (externalAutoDetect == DETECTION_SENTINEL))
#endif
					)
				{
					sensorDataId = 0;
					externalUART_Protocol = protocol;
					MX_USART1_UART_DeInit();
					if( protocol != 0)
					{
						MX_USART1_UART_Init();
					}
				}
			break;
		default:
			break;
	}
}

void externalInterface_SetCO2Value(uint16_t CO2_ppm)
{
	float local_ppm = CO2_ppm * 10.0;		/* scalfactor */

#ifndef ENABLE_EXTERNAL_PRESSURE
	float local_corr = 0.0;

	if (local_ppm >= LOOKUP_CO2_CORR_TABLE_MAX)
	{
		local_corr = -0.0014;
	}
	else
	{
		local_corr = LookupCO2PressureCorrection[((uint16_t) (local_ppm / LOOKUP_CO2_CORR_TABLE_SCALE))];
	}
	local_ppm = local_ppm / (1.0 + (local_corr * (get_surface_mbar() - get_pressure_mbar())));
#else
/* The external pressure value is passed via ADC channel2 and calibration is done at firmware => just forward sensor data */
/* compensation is done at firmware side. This is for testing only. Take care the the same algorithm is taken as used for the lookup table */
#endif
	externalCO2Value = local_ppm / 10.0;
}

void externalInterface_SetCO2SignalStrength(uint16_t LED_qa)
{
	externalCO2SignalStrength = LED_qa;
}

uint16_t externalInterface_GetCO2Value(void)
{
	return externalCO2Value;
}

uint16_t externalInterface_GetCO2SignalStrength(void)
{
	return externalCO2SignalStrength;
}


void externalInterface_SetCO2State(uint16_t state)
{
	externalCO2Status = state;
}

uint16_t externalInterface_GetCO2State(void)
{
	return externalCO2Status;
}


uint8_t externalInterface_GetSensorData(uint8_t* pDataStruct)
{

	if((pDataStruct != NULL) && sensorDataId != 0)
	{
		memcpy(pDataStruct, &sensorDataDiveO2, sizeof(sensorDataDiveO2));
	}
	return sensorDataId;
}

void externalInterface_SetSensorData(uint8_t dataId, uint8_t* pDataStruct)
{
	if(pDataStruct != NULL)
	{
		if(dataId != 0)
		{
			memcpy(&sensorDataDiveO2, pDataStruct, sizeof(sensorDataDiveO2));
		}
		else
		{
			memset(&sensorDataDiveO2,0,sizeof(sensorDataDiveO2));
		}
		sensorDataId = dataId;
	}
}

void externalInface_SetSensorMap(uint8_t* pMap)
{
	if(pMap != NULL)
	{
		memcpy(MasterSensorMap, pMap, 5);		/* the map is not directly copied. Copy is done via cmd request */
	}

}
uint8_t* externalInterface_GetSensorMapPointer(uint8_t finalMap)
{
	uint8_t* pret;

	if((externalAutoDetect != DETECTION_OFF) && (!finalMap))
	{
		pret = tmpSensorMap;
	}
	else
	{
		pret = SensorMap;
	}
	return pret;
}

void externalInterface_AutodetectSensor()
{
	static uint8_t	sensorIndex = 0;
	uint8_t index = 0;

	if(externalAutoDetect != DETECTION_OFF)
	{
		switch(externalAutoDetect)
		{
			case DETECTION_INIT:	sensorIndex = 0;
									tmpSensorMap[0] = SENSOR_OPTIC;
									tmpSensorMap[1] = SENSOR_OPTIC;
									tmpSensorMap[2] = SENSOR_OPTIC;
									tmpSensorMap[3] = SENSOR_NONE;
									tmpSensorMap[4] = SENSOR_NONE;

									if(externalInterfacePresent)
									{
										externalInterface_SwitchPower33(0);
										externalInterface_SwitchUART(0);
										for(index = 0; index < MAX_ADC_CHANNEL; index++)
										{
											externalChannel_mV[index] = 0;
										}
										externalAutoDetect = DETECTION_START;
									}
									else
									{
										externalAutoDetect = DETECTION_DONE;	/* without external interface O2 values may only be received via optical port => return default sensor map */
									}
				break;
			case DETECTION_START:		tmpSensorMap[0] = SENSOR_ANALOG;
										tmpSensorMap[1] = SENSOR_ANALOG;
										tmpSensorMap[2] = SENSOR_ANALOG;
										externalInterface_SwitchPower33(1);
										externalInterface_SwitchADC(1);
										externalAutoDetect = DETECTION_ANALOG1;
				break;
			case DETECTION_ANALOG1:	externalAutoDetect = DETECTION_ANALOG2;		/* do a second loop to make sure all adc channels could be processed */
				break;
			case DETECTION_ANALOG2:	for(index = 0; index < MAX_ADC_CHANNEL; index++)
									{
										if(externalChannel_mV[index] > MIN_ADC_VOLTAGE_MV)
										{
											tmpSensorMap[sensorIndex++] = SENSOR_ANALOG;
										}
										else
										{
											tmpSensorMap[sensorIndex++] = SENSOR_NONE;
										}
									}
									externalAutoDetect = DETECTION_DIGO2;
									externalInterface_SwitchUART(EXT_INTERFACE_UART_O2 >> 8);
				break;
			case DETECTION_DIGO2:	if(UART_isDigO2Connected())
									{
										for(index = 0; index < 3; index++)	/* lookup a channel which may be used by digO2 */
										{
											if(tmpSensorMap[index] == SENSOR_NONE)
											{
												break;
											}
										}
										if(index == 3)
										{
											tmpSensorMap[2] = SENSOR_DIGO2;  /* digital sensor overwrites ADC */
										}
										else
										{
											tmpSensorMap[index] = SENSOR_DIGO2;
										}

										UART_setTargetChannel(index);
										/* tmpSensorMap[sensorIndex++] = SENSOR_DIGO2; */
									}
									externalAutoDetect++;
#ifdef ENABLE_CO2_SUPPORT
									externalInterface_SwitchUART(EXT_INTERFACE_UART_CO2 >> 8);
				break;
			case DETECTION_CO2:		if(UART_isCO2Connected())
									{
										for(index = 0; index < 3; index++)	/* lookup a channel which may be used by CO2*/
										{
											if(tmpSensorMap[index] == SENSOR_NONE)
											{
												break;
											}
										}
										if(index == 3)
										{
											tmpSensorMap[sensorIndex++] = SENSOR_CO2;  /* place Co2 sensor behind O2 sensors (not visible) */
										}
										else
										{
											tmpSensorMap[index] = SENSOR_CO2;
										}

									}
									externalAutoDetect++;
#endif
#ifdef ENABLE_SENTINEL_MODE
									externalInterface_SwitchUART(EXT_INTERFACE_UART_SENTINEL >> 8);
									UART_StartDMA_Receiption();
				break;

			case DETECTION_SENTINEL:
			case DETECTION_SENTINEL2:
									if(UART_isSentinelConnected())
									{
										for(index = 0; index < 3; index++)	/* Sentinel is occupiing all sensor slots */
										{
											tmpSensorMap[index] = SENSOR_SENTINEL;
										}
										sensorIndex = 3;
									}
									externalAutoDetect++;
#endif
				break;
			case DETECTION_DONE:	for(index = 0; index < EXT_INTERFACE_SENSOR_CNT; index++)
									{
										if(tmpSensorMap[index] != SENSOR_NONE)
										{
											break;
										}
									}

									if(index != EXT_INTERFACE_SENSOR_CNT)		/* return default sensor map if no sensor at all has been detected */
									{
										while(sensorIndex < EXT_INTERFACE_SENSOR_CNT)
										{
											tmpSensorMap[sensorIndex++] = SENSOR_NONE;
										}
									}
									else
									{
										tmpSensorMap[0] = SENSOR_OPTIC;
										tmpSensorMap[1] = SENSOR_OPTIC;
										tmpSensorMap[2] = SENSOR_OPTIC;
									}
									memcpy(SensorMap, tmpSensorMap, sizeof(tmpSensorMap));
									externalAutoDetect = DETECTION_OFF;
				break;
			default:
				break;
		}
	}
}


void externalInterface_ExecuteCmd(uint16_t Cmd)
{
	char cmdString[10];
	uint8_t cmdLength = 0;
	uint8_t index;

	switch(Cmd & 0x00FF)		/* lower byte is reserved for commands */
	{
		case EXT_INTERFACE_AUTODETECT:	externalAutoDetect = DETECTION_INIT;
										for(index = 0; index < 3; index++)
										{
											SensorMap[index] = SENSOR_SEARCH;
										}
			break;
		case EXT_INTERFACE_CO2_CALIB:	cmdLength = snprintf(cmdString, 10, "G\r\n");
			break;
		case EXT_INTERFACE_COPY_SENSORMAP:	if(externalAutoDetect == DETECTION_OFF)
											{
												memcpy(SensorMap, MasterSensorMap, 5);
												for(index = 0; index < 3; index++)
												{
													if(SensorMap[index] == SENSOR_DIGO2)
													{
														break;
													}
												}
												UART_setTargetChannel(index); /* if no slot for digO2 is found then the function will be called with an invalid parameter causing the overwrite function to fail */
											}
			break;
		default:
			break;
	}
	if(cmdLength != 0)
	{
		HAL_UART_Transmit(&huart1,(uint8_t*)cmdString,cmdLength,10);
	}
	return;
}