MMA7360Q
3 Axis XYZ
12 bit
Accelerometer
20x4 Character
LCD Display
12 bit MPXV5004
Integrated
Menu Buttons
Pressure
Sensor
JM60
8-bit S08 MCU
12-bit ADC
60k Flash
USB
MPL115A2
(I2C)
24-bit
ADC
Converter
Instrumentation
Amplifier
Gain=98.8
MPXM2102
Compensated
Pressure
12 bit
Temp
Sensor
Sensor
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.
AN3956
Sensors
Freescale Semiconductor
2
FREESCALE [ Freescale ]
