User's Manual Part 1

Sensor Board description
Wireless Sensing Triple Axis Reference design, Rev. 0.9
16 Freescale Semiconductor
Figure 3-2Sensor board block diagram
Figure 3-3 shows in more detail, how different software and hardware modules co-operate with each
other. The main task of the Sensor board is to:
• periodically wake-up from power saving mode
• measure all three XYZ acceleration values from the sensor
• compose a data frame using simple
ZSTAR RF protocol
• use SMAC (Simple Media Access Controller) to send this data frame over the RF link
• wait for an acknowledgment from the other end (here, the USB stick)
• go to sleep
This basic loop repeats roughly 20 times per second providing nearly a real-time response from the
sensor.
MMA7260Q
accelerometer
X Y Z sleep g-select
MC9S08QG8
MCU
MC13191
2.4GHz RF
receive antenna
transmit antenna
SPI
IRQ
CR2032 or CR2477
Lithium battery