Published July 30, 2016

Analog Pressure Sensor

A 0-15 psi analog pressure sensor made using the PSoC Analog Coprocessor and TE's pressure sensor.

BeginnerFull instructions provided1,932

Things used in this project

Hardware components

Cypress PSoC Analog Coprocessor Pioneer Kit

TE 1210 Analog Pressure Sensor 0-15Psi

Software apps and online services

Cypress PSoC Creator

Story

This project shows how to use the TE/MEAS Analog Pressure Sensor (1210A-015A-3L) with the PSoC Analog Coprocessor to measure absolute pressure.

The TE analog pressure sensor is spec'd to work in the 0-15 Psi range and provides a differential voltage-output that changes based on the measured pressure through a tube on the sensor. The sensor requires current excitation which is provided from the PSoC, using its internal voltage reference and opamp. The differential signal from the sensor is amplified using PSoC's internal opamps, configured as a differential amplifier circuit. The amplified signal is then fed to PSoC's internal ADC which converts the analog signals into digital values representing the absolute pressure. The digital values of pressure sensor are then sent over I2C to a PC where they can be visualized in graphs.

The TE Analog Pressure Sensor's datasheet recommends the following application schematic to measure the voltage changes. The sensor is excited using 1.5mA of current. Based on the pressure value, a voltage signal gets generated at the sensor's output terminals. To compensate for temperature variations it provides a laser-trimmed Gain Set resistor.

Application Schematic Required by the TE Sensor

Since the PSoC Analog Coprocessor has internal opamps and an internal voltage reference, it can easily recreate the required application schematic using the PSoC Creator tool. In this project, 0.45mA of current was generated by the "Voltage-to-Current Converter" block in the schematic below. This current was then used to excite the sensor. The output voltage was amplified and measure using the "Analog Front End" block in the schematic below, which comprised of a differential amplifier circuit (using the 2 opamps) and an ADC.

Sensor Schematic Implemented in PSoC Creator

Modifications to the CY8CKIT-048 PSoC Analog Pioneer Kit:

- remove resistors R54, R81, R82, R124, R131, R134, R156, R161 (because these are connected to the sensors on the board)

- solder a 1 uF capacitor at C43 (required as the ADC bypass cap). If this cap isn't soldered, then disable the "VRef Bypass" option in ScanADC Component in PSoC Creator.

Pressure Sensor connected to the PSoC Analog Kit

To read the sensor values on a PC, you can use Cypress Bridge Control Panel software tool, which displays the I2C output from the board on the PC (via USB port).

Pressure Changes Visualized on a PC

Code

#include <project.h>

/* Constants */
#define     CHANNEL_ID      0
#define     MVOLTS_TO_PSI   60.867

/* System variables */
struct SystemVars{
    uint16 ADC_Value;
    float Pressure_Value;
}MyBuffer;

/* Initialize system resources */
void InitializeSystem(void)
{
    /* Enable programmable reference and Opamp to generate 
       0.45mA excitation current */
    PVref_Start();
    PVref_Enable();
    V_TO_I_Start();
    
    /* Enable the differential amplifier */
    DiffAmp_1_Start();
    DiffAmp_2_Start();
    
    /* Start ADC and enable conversion*/
    ADC_Start();
    ADC_StartConvert();
        
    /* Enable I2C for debugging */
    EZI2C_Start();
    EZI2C_EzI2CSetBuffer1(sizeof(MyBuffer), sizeof(MyBuffer), (uint8 *) &MyBuffer);
}

int main()
{ 
    /* Enable global interrupts. */
    CyGlobalIntEnable; 
    
    /* Initialize system resources */
    InitializeSystem();

    for(;;)
    {
        /* Wait for ADC sample to complete */
        ADC_IsEndConversion(ADC_WAIT_FOR_RESULT);
        
        /* Read ADC value in milliVolts */
        MyBuffer.ADC_Value = ADC_CountsTo_mVolts(CHANNEL_ID, ADC_GetResult16(CHANNEL_ID)); 
        
        /* Convert ADC value to pressure value */
        MyBuffer.Pressure_Value = (float) (MyBuffer.ADC_Value/MVOLTS_TO_PSI);
    }
}

/* [] END OF FILE */

Credits

Pushek Madaan

2 projects • 7 followers

I like to checkout new technology, work on new products, design solutions and define products...

Analog Pressure Sensor

Things used in this project

Hardware components

Software apps and online services

Story

Schematics

project datasheet

Code

PSoC Analog Pressure Sensor Project (PSoC Creator)

Firmware

Credits

Pushek Madaan

Comments

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Analog Pressure Sensor

Analog Pressure Sensor

Things used in this project

Hardware components

Software apps and online services

Story

Schematics

project datasheet

Code

PSoC Analog Pressure Sensor Project (PSoC Creator)

Firmware

Credits

Pushek Madaan

Comments

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