1300 Henley Court Pullman, WA 99163 509.334.6306 www.digilentinc.com PmodDPG1 Reference Manual Revised August 10, 2016 This manual applies to the PmodDPG1 Rev. A Overview The Digilent PmodDPG1 (Revision A) is a differential gauge pressure module. With NXP s MP3V5010DP piezoresistive transducer and Texas Instrument s ADCS7476 12-bit Analog-to-Digital Converter, you can detect when a change in pressure between the two ports occurs and send digital information to your system board. Features include: Differential gauge pressure transducer 12-bit ADC 0 to 10 kPa differential pressure range Temperature compensated and calibrated 6-pin Pmod connector with SPI interface Follows Digilent Pmod Interface Specification Type 2 The PmodDPG1. 1 Functional Description The PmodDPG1 is designed to detect a gauge pressure ranging from 0 kPa to 10 kPa with a piezoresistive transducer and use an embedded 12-bit ADC to provide the user with a serial stream of data representative of the measured pressure. Copyright Digilent, Inc. All rights reserved. DOC : 510-333 Page 1 of 4 Other product and company names mentioned may be trademarks of their respective owners. PmodDPG1 Reference Manual 2 Specifications 1 Parameter Min Typical Max Units Recommended Operating Voltage 3.125 3.3 3.5 V Maximum Supply Voltage - - 5.5 V 2 Maximum Pressure - - 75 kPa 3 Minimum Pressure Offset 0.1 0.24 0.38 V Sensor Accuracy -0.54 0 0.54 kPa Parameter Value Units 4 Communication Protocol SPI Mode 0 5 Power Supply Current draw 10 mA Sensor Response Time 1 mS Sensor Bandwidth 500 Hz 1 Note - Data in the Typical Column uses VCC at 3.3V unless otherwise noted 2 Note - Where the pressure at P1 (top nozzle) is greater than the pressure at P2 (bottom nozzle) 3 Note - Output voltage corresponding to a pressure differential of 0 kPa 4 Note - CPOL = 0, CHPA = 0 5 Note - Normal operation with VCC at 3.3V 3 Interfacing with the Pmod The PmodDPG1 communicates with the host board via the SPI protocol with SPI Mode 0 (CPOL = 0, CHPA = 0). The 12 bits of digital data are sent to the system board in 16 clock cycles with the most significant bit first. For the embedded ADC7476, each bit is shifted out on each falling edge of the serial clock line after the chip select line is brought low with the first four bits as leading zeroes and the remaining bits representing the 12 bits of data. The datasheet for the ADC7476 recommends that for faster microcontrollers or DSPs that the serial clock line is first brought to a high state before being brought low after the fall of the chip select line to ensure that the first bit is valid. As a differential pressure module, it should be noted that the Pmod can only accept a certain range of pressure differences without damaging the internal piezoresistive silicon. When the Pmod is laid on a flat surface such that transducer is above the PCB, the top most nozzle is P1 (the receiving nozzle to detect fluctuating pressure) and the bottom most nozzle is P2 (the pressure reference nozzle for P1). The pressure at P1 is recommended to be between 0 and 10 kPa above the pressure present at P2. Pressures outside of this range may cause permanent damage to the device. To convert the serial data stream back into a corresponding pressure, users may use the following equation: Copyright Digilent, Inc. All rights reserved. Page 2 of 4 Other product and company names mentioned may be trademarks of their respective owners.