diff Small_CPU/Src/externalInterface.c @ 554:3328189786e7

Added external ADC interface functionality (MCP3424): Added communication protocoll to read data from external ADC. At the moment 16bit and 18bit resolutions are supported. External data will be read and forwarded depending on the conversion time of the ADC.
author Ideenmodellierer
date Thu, 12 Nov 2020 19:46:03 +0100
parents
children 84a4e1200726
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--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Small_CPU/Src/externalInterface.c	Thu Nov 12 19:46:03 2020 +0100
@@ -0,0 +1,161 @@
+/**
+  ******************************************************************************
+  * @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 "i2c.h"
+#include "externalInterface.h"
+#include "scheduler.h"
+
+extern SGlobal global;
+
+#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)
+
+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];
+
+
+void externalInterface_Init(void)
+{
+	activeChannel = 0;
+	timeoutCnt = 0;
+	externalInterfacePresent = 0;
+	if(externalInterface_StartConversion(activeChannel) == HAL_OK)
+	{
+		externalInterfacePresent = 1;
+		global.deviceDataSendToMaster.hw_Info.extADC = 1;
+	}
+}
+
+
+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;
+
+	if(externalInterfacePresent)
+	{
+		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 */
+				activeChannel++;
+				if(activeChannel == MAX_ADC_CHANNEL)
+				{
+					activeChannel = 0;
+				}
+				externalInterface_StartConversion(activeChannel);
+				timeoutCnt = 0;
+			}
+			else
+			{
+				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;
+}