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Liquid-Level Monitoring Using a Pressure Sensor #5 - Using Vivado and Testing the System

guillengap

Table of Contents

  1. Project Introduction
  2. Getting Started
  3. Calibrating the MPX2050DP Pressure Sensor
  4. Calculations and Noise Reduction
  5. Using Vivado and Testing the System
  6. Project Report Updated

**********************************************************************************************************************

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Using Vivado

Here I have used the same project from the third blog, that is: "Cmod S7-25 XADC Demo"

image

I have used and modified the "Cmod S7-25 XADC Demo" example. So the main.c looks as shown below:

 

/*
 * This is the demo main file for the Cmod S7-25 XADC demo.
 *
 * Changelog:
 * 06/07/2018 (ArtVVB): Created
 *
 * */

#include "xparameters.h"
#include "xsysmon.h"
#include "xil_printf.h"
#include "xil_cache.h"
#include "sleep.h"

#define XADC_DEVICE_ID (XPAR_XADC_WIZ_0_DEVICE_ID)

// TODO: create an "xadc/" subdirectory of project src. make as portable to other boards/xadc configs as possible
typedef struct XadcInfo {
	int NumChannels;
	int Channels[2];
	int ChannelIsDiff[2];
	char *ChannelNames[2];
} XadcInfo;

typedef struct Xadc_ChannelInfo {
	int SequencerIndex;
	int IsDiff;
	char *Name;
} Xadc_ChannelInfo;


void Xadc_Init(XSysMon *InstancePtr, const Xadc_ChannelInfo DeviceInfo[], const int NumChannels, const u32 DeviceId);
void Xadc_ReadData(XSysMon *InstancePtr, const Xadc_ChannelInfo DeviceInfo[], const int NumChannels, u16 RawData[]);
void EnableCaches();
void DisableCaches();

// Initialize the XADC Wizard IP
void Xadc_Init(XSysMon *InstancePtr, const Xadc_ChannelInfo DeviceInfo[], const int NumChannels, const u32 DeviceId) {
	u32 ChannelsMask;
	u32 InputModeMask;
	int i;
	XSysMon_Config *xadc_cfg_ptr;
	xadc_cfg_ptr = XSysMon_LookupConfig(DeviceId);
	XSysMon_CfgInitialize(InstancePtr, xadc_cfg_ptr, xadc_cfg_ptr->BaseAddress);

	ChannelsMask = 0;
	InputModeMask = 0;
	for (i = 0; i < NumChannels; i++) {
		ChannelsMask |= 1 << DeviceInfo[i].SequencerIndex;
		if (DeviceInfo[i].IsDiff)
			InputModeMask |= 1 << DeviceInfo[i].SequencerIndex;
	}
	// Disable the Channel Sequencer before configuring the Sequence registers.
	XSysMon_SetSequencerMode(InstancePtr, XSM_SEQ_MODE_SAFE);

	// Leave alarm enables default
	// Leave channel averaging default

	// Set single-ended input mode for all channels
	XSysMon_SetSeqInputMode(InstancePtr, InputModeMask);

	// Leave acquisition time default
	XSysMon_SetSeqAcqTime(InstancePtr, ChannelsMask);
	// Enable all channels
	XSysMon_SetSeqChEnables(InstancePtr, ChannelsMask);

	// Leave the ADCCLK frequency default
	// Leave calibration default

	// Enable the Channel Sequencer in continuous sequencer cycling mode
	XSysMon_SetSequencerMode(InstancePtr, XSM_SEQ_MODE_CONTINPASS);
}

// Captures Data from each XADC Channel
void Xadc_ReadData(XSysMon *InstancePtr, const Xadc_ChannelInfo DeviceInfo[], const int NumChannels, u16 RawData[]) {
	//TODO: implement timeout on status check
	int i;

	// Clear the Status
	XSysMon_GetStatus(InstancePtr);

	// Wait until the End of Sequence occurs
	while ((XSysMon_GetStatus(InstancePtr) & XSM_SR_EOS_MASK) != XSM_SR_EOS_MASK);

	//Capture data from each channel, return via RawData
	for (i = 0; i < NumChannels; i++) {
		RawData[i] = XSysMon_GetAdcData(InstancePtr, DeviceInfo[i].SequencerIndex);
	}

	return;
}

int main() {
	const int NumChannels = 2;
	const Xadc_ChannelInfo CmodS7_XadcInfo[2] = {
		{21, 0, "AIN_32"}, // VAUX_5
		{28, 0, "AIN_33"}  // VAUX_12
	};
	const int Xadc_VoltageScaler_SingleEnded = (0xFFFF) / (1000 * 3.3);   // FROM 0 TO 3300 mv

	XSysMon Xadc_Ctrl;
	u16 Xadc_RawData[2];
	int Xadc_Voltage; // x100 from actual value. Two decimal point precision.
	int Xadc_VoltageRemainder;
	//float X_test;
	int i;

	EnableCaches();
	xil_printf("Initializing Cmod S7-25 XADC Demo...\n\r");
	Xadc_Init(&Xadc_Ctrl, CmodS7_XadcInfo, NumChannels, XADC_DEVICE_ID);
	xil_printf("Demo Initialized\n\r");

	while (1) {
		Xadc_ReadData(&Xadc_Ctrl, CmodS7_XadcInfo, NumChannels, Xadc_RawData);
		for (i = 0; i < NumChannels; i++) {
			// Convert raw data in this channel to an int in the range 0 to 330, representing
			// the voltage on that input channel multiplied by 100
			Xadc_Voltage = ((int)Xadc_RawData[i] / Xadc_VoltageScaler_SingleEnded);
			if ((Xadc_Voltage == 1890)) {
				xil_printf("%s h->00cm ");
			}
			if ((Xadc_Voltage >= 1891 && Xadc_Voltage <= 1894)) {
				xil_printf("%s h->01a05cm ");
			}
			if ((Xadc_Voltage >= 1895 && Xadc_Voltage <= 1898)) {
				xil_printf("%s h->06a10cm ");
			}
			if ((Xadc_Voltage >= 1899 && Xadc_Voltage <= 1902)) {
				xil_printf("%s h->11a15cm ");
			}
			if ((Xadc_Voltage >= 1903 && Xadc_Voltage <= 1906)) {
				xil_printf("%s h->16a20cm ");
			}
			if ((Xadc_Voltage >= 1907)) {
				xil_printf("%s h->21cm ");
			}

			Xadc_VoltageRemainder = Xadc_Voltage % 1000;
			Xadc_Voltage = (Xadc_Voltage/1000) % 100;

			// Print the name of the channel, followed by the voltage
			xil_printf("%s: %01d.%03dV    ",
					CmodS7_XadcInfo[i].Name,
					Xadc_Voltage,
					Xadc_VoltageRemainder
			);
		}
		xil_printf("\n\r");
		usleep(500000); // wait 500ms
	}
	DisableCaches();

	return 0;
}

void EnableCaches() {
#ifdef __MICROBLAZE__
#ifdef XPAR_MICROBLAZE_USE_DCACHE
   Xil_DCacheEnable();
#endif
#ifdef XPAR_MICROBLAZE_USE_ICACHE
   Xil_ICacheEnable();
#endif
#endif
}

void DisableCaches() {
#ifdef __MICROBLAZE__
#ifdef XPAR_MICROBLAZE_USE_DCACHE
   Xil_DCacheDisable();
#endif
#ifdef XPAR_MICROBLAZE_USE_ICACHE
   Xil_ICacheDisable();
#endif
#endif
}

Main modifications:

  • Voltage range from 0 to 3300 millivolts

const int Xadc_VoltageScaler_SingleEnded = (0xFFFF) / (1000 * 3.3);   // FROM 0 TO 3300 mv

  • Height readings range was 5 centimeters

if ((Xadc_Voltage == 1890)) {
xil_printf("%s h->00cm ");
}
if ((Xadc_Voltage >= 1891 && Xadc_Voltage <= 1894)) {
xil_printf("%s h->01a05cm ");
}
if ((Xadc_Voltage >= 1895 && Xadc_Voltage <= 1898)) {
xil_printf("%s h->06a10cm ");
}
if ((Xadc_Voltage >= 1899 && Xadc_Voltage <= 1902)) {
xil_printf("%s h->11a15cm ");
}
if ((Xadc_Voltage >= 1903 && Xadc_Voltage <= 1906)) {
xil_printf("%s h->16a20cm ");
}
if ((Xadc_Voltage >= 1907)) {
xil_printf("%s h->21cm ");
}

  • Print readings with thousandths of voltage

Xadc_VoltageRemainder = Xadc_Voltage % 1000;
Xadc_Voltage = (Xadc_Voltage/1000) % 100;

  • Take readings every 500 milliseconds

usleep(500000); // wait 500ms

Testing the System

First, it is necessary to glue the hose with silicone on the water container. Below you see a simple tour of this project before putting it to the test.

The tests performed are shown below.

Conclusion

  • At the end of this project I can say that it is possible to use a pressure sensor to measure the water level in a container.
  • In my case the MPX2050DP pressure sensor handles small voltages from 0 to 50 millivolts. Even with the op amp I only managed to increase it a gain of 200 millivolts.
  • In my experiment, I was able to measure distances of 5 centimeters, equivalent to 1 liter of water in the used container. This would be very useful to measure the water level of a tank in which you could measure from 0 to 200 liters.
  • If I want to improve the resolution, for example to measure centimeter distances, then it is necessary to use a smaller and more sensitive sensor, for example the MPX5010, which has an output of 0 to 5 volts and without using an operational amplifier.