MPM7888 Digital Pressure Sensor

http://www.microsensor.cn Add: No.18, Yingda Road Baoji, P.R. China, Tel: +86 917 3600739/3600909

MPM7888 is a miniaturized Digital Barometric Air Pressure Sensor with a high accuracy and a low current consumption. It is both a pressure and a temperature sensor. The pressure sensor element is based on a capacitive sensing principle which guarantees a high precision during temperature changes. The small package makes MPM7888 ideal for mobile applications and wearable devices.MPM7888‘s internal signal processor converts the output from the pressure and temperature sensor elements to 24-bit results. Each pressure sensor has been calibrated individually and contains calibration coefficients....

MPM7888 Digital Pressure Sensor(V1.0) Table 1: Test condition http://www.microsensor.cn Add: No.18, Yingda Road Baoji, P.R. China, 721006

MICRO SENSOR CO.,LTD 5.1 Operating Modes http://www.microsensor.cn Add: No.18, Yingda Road Baoji, P.R. China, 721006

MPM7888 supports 3 different modes of operation: Standby, Command, and Background mode Standby Mode ——Default mode after power on or reset. No measurements are performed. ——All registers and compensation coefficients are accessible. Command Mode ——One temperature or pressure measurement is performed according to the selected precision. — — The sensor will return to Standby Mode when the measurement is finished, and the measurement result will be available in the data registers. Background Mode — — Pressure and/or temperature measurements are performed continuously according to the selected measurement...

MPM7888 can be accessed as a slave device through either SPI 3-wire, SPI 4-wire, or I2C serial interface. 5.3.1 I2C Interface -The sensor's default interface. -The sensor's address is 0x77 (default) or 0x76 (if the SDO pin is pulled-down to GND) I2C write Writing is done by sending the slave address in write mode (RW=’0’), resulting in slave address 111011X0 (‘X’ is determined by state of SDO pin. Then the master sends pairs of register addresses and register data. The transaction is ended by a stop condition. I2C read To be able to read registers, first the register address must be sent in write...

MPM7888 Digital Pressure Sensor(V1.0) default SPI interface. -To enable SPI 3-wire configuration, a bit must be set in the Interrupt and FIFO configuration (CFG_REG) register after start up. CSB is active low and has an integrated pull-up resistor. Data on SDA is latched by the device at SCK rising edge and SDO is changed at SCK falling edge. Communication starts when CSB goes to low and stops when CSB goes to high; during these transitions on CSB, SCK must be stable. csb+j t ir In SPI mode, only 7 bits of the register addresses are used; the MSB of register address is not used and replaced...

5.4 Interrupt MPM7888 can generate an interrupt when a new measurement result is available and/or when the FIFO is full. The sensor uses the SDO pin for the interrupt signal, and interrupt is therefore not supported if the interface is 4-wire SPI. The interrupt is enabled and configured in the Interrupt and FIFO configuration (CFG_REG) register. The SDO pin serves as both interrupt and as the least significant bit in the device address. If the SDO pin is pulled low the interrupt polarity must be set to active high and vice versa. The interrupt status can be read from the Interrupt Status (INT_STS)...

MPM7888 Digital Pressure Sensor(V1.0) register. 5.6 Calibration and Measurement Compensation MPM7888 is a calibrated sensor and contains calibration coefficients. These are used in the application (for instance by the host processor) to compensate the measurement results for sensor non-linearity’s. The sections that follow, describe how to calculate the compensated results and convert them into Pa and °C values. 5.6.1 a) How to Calculate Compensated Pressure Values Read the calibration coefficients (c00, c10, c20, c30, c01, c11, and c21) from the Calibration Coefficient register. Note: The coefficients...

MPM7888 Digital Pressure Sensor(V1.0) Table 4: Compensation Scale Factors 6.2 Application Circuit Example The example application circuit example uses the I2C serial interface. The SDO pin can be used for interrupt or to set least significant bit of the device address. http://www.microsensor.cn Add: No.18, Yingda Road Baoji, P Tel: +86 917 3600739/3600909 Top View iPad not Visible)

Figure 1: Typical application circuit Table 6: Component Values Component Pull-up/down Resistor Supply Blocking Capacitor Note / Test Condition R3 is optional and will set the address to 0x76 instead of 0x77. The blocking capacitors should be placed as close to thepackage pins as possible. Calculating Absolute Altitude and Calculating Pressure at Sea Level With the measured pressure P and the pressure at sea level P0=1013.25hPa, the altitude in meters can be calculated with the international barometric formula: Thus, a pressure change of ΔP = 1hPa corresponds to 8.43m at sea level. http://www.microsensor.cn...

1000 At tude n standard atmosphere Barometric pressure [hPal With the measured pressure P and the absolute altitude the pressure at sea level can be calculated: Thus, a difference in altitude of Aaltitude = 10m corresponds to 1.2hPa pressure change at sea level. MICRO SENSOR CO.,LTD http://www.microsensor.cn Add: No.18, Yingda Road Baoji, P.R. China, 721006

http://www.microsensor.cn Add: No.18, Yingda Road Baoji, P.R. China, 721006 MICRO SENSOR CO.,LTD

8.1.3 PRS_B0 The lowest byte of the three bytes measured pressure value. PRS_B0 Address 02H Pressure (XLSB data)Reset value:00H 8.2.3 TMP_B0 The lowest part of the three bytes measured temperature value. MICRO SENSOR CO.,LTD http://www.microsensor.cn Add: No.18, Yingda Road Baoji, P.R. China, 721006

TMP_B0 Temperature (XLSB data) Address Reset value: *) Note: See Interrupt and FIFO configuration (CFG_REG) register*) MICRO SENSOR CO.,LTD http://www.microsensor.cn Add: No.18, Yingda Road Baoji, P.R. China, 721006 Tel: +86 917 3600739/3600909 Fax: 3609977