RD3172MMA7455L Freescale Semiconductor, RD3172MMA7455L Datasheet - Page 24

• Manufacturer Part Number: RD3172MMA7455L
• Description: EVAL BOARD FOR MMA7455L
• Manufacturer: Freescale Semiconductor
• Series: ZSTAR3r

Specifications of RD3172MMA7455L

• Design Resources: ZSTAR3 Schematic
• Sensor Type: Accelerometer, 3 Axis
• Sensing Range: ±2g, 4g, 8g
• Interface: RF
• Sensitivity: 16, 32, 64 LSB/g
• Voltage - Supply: 3V
• Embedded: Yes, MCU, 16-Bit
• Utilized Ic / Part: MMA7455
• Acceleration: 5000 g
• Sensing Axis: Triple Axis
• Output Type: Digital
• Interface Type: I2C, SPI
• Operating Voltage: 3.6 L
• Operating Current: 490 uA
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: MMA7455L

ZSTAR3 Sensor Board Description
3.2.2
The software uses for both types of sensor an auto calibration process to get the offset calibration values.
It uses a simple 0g X, 0g Y, +1g Z auto calibration method. The sensor board runs the auto calibration
process for each g scale of the sensor, and thus uses an individual set of calibration values for each g scale.
For more details, see Freescale application note AN3447, “Implementing Auto-Zero Calibration
Techniques for Accelerometers” at www.freescale.com.
3.2.3
The 3-axis accelerometer sensor MMA7361L provides three separate analog levels for the X, Y and Z axis.
These outputs are ratiometric, which means that the output offset voltage and sensitivity will scale linearly
with the applied supply voltage. This is a key feature when interfacing to a microcontroller with A/D
converter reference levels tied to a power supply, because it provides a system level cancellation of supply
induced errors in the analog-to-digital conversion process.
During the analog-to-digital conversion in the microcontroller, 10-bit resolution is used. MC13213 A/D
channels 0, 1 and 2 are connected to X (channel 1), Y (channel 2) and Z (channel 0) outputs of the
MMA7361L. The microcontroller’s APCTL1 register enables these ADC channels for I/O pin control by
the ADC module.
The ADCCFG register controls the selected mode of operation, clock source, clock divide, and
configuration for low power or long sample times.
The MMA7361L sensor implements a digital output for the freefall detection module. This output is
connected directly to the KeyBoard Interrupt (KBI) module and it’s used as the default source for freefall
detection.
3.2.4
The ZSTAR3 sensor board provides support for sensors with digital interface. The interface contains pins
routed to KBI, I
standard that can be handled by GPIO pins controlled by software. Also the KBI interface can supports
interrupt signals of used sensors.
1. This is valid for 00288_04 PCB revision (red edition). See chapter 3.4 New PCB Revision 00288_04. The old one version of
PCB 00288_02 doesn’t provide external pull-up’s on I
24
Auto Calibration Process
Analog Sensor Software Support
Digital Sensor Software Support
2
C and general GPIO pins. So the interface can handle hardware I
2
C bus.
DRM103, Rev. 2
2
C bus
Freescale Semiconductor
1
, or any other