AN3956

Sensors

Freescale Semiconductor

2

Figure 2. Simplified Block Diagram

Figure 2 is a simplified block diagram of the DEMOAPEXSENSOR. The sensors with analog outputs (Table 1) are sampled

via the JM60 microcontroller’s 12-bit ADC. The exception is the MPXM2102A absolute pressure sensor. This is used for altitude

so it requires a high resolution sampling. It passes through an instrumentation amplifier and then is interfaced via an external

24-bit ADC chipset before communication via SPI to the JM60 MCU. The JM60 interfaces with the LCD screen and processes

inputs by the user for the displayed output.

Several Algorithms are used to calculate functions on the DEMOAPEXSENSOR.

Information on implementing the MPL115A can be found in

AN3785, How to Implement the Freescale MPL115A Digital Barometer.

Implementing the MPL115A as a barometer and altimeter can be found in

AN3914, Modern Altimeter and Barometer System using the MPL115A.

More pressure sensor application notes can be found at: www.freescale.com/pressure.

MPXV5004

Integrated

Pressure

Sensor

MMA7360Q

3 Axis XYZ

Accelerometer

MPXM2102

Compensated

Pressure

Sensor

24-bit

ADC

Converter

Temp

Sensor

JM60

8-bit S08 MCU

12-bit AD C

60k Flash

USB

20x4 Character

LCD Display

12 bit

12 bit

Menu Buttons

MPL115A2

(I2C)

Instrumentation

Amplifier

Gain=98.8

12 bit