User Manual

USB stick Board Description
ZSTAR3 Reference Design Manual, Rev. 0.1
4-30 Freescale Semiconductor
Preliminary
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Figure 4-2. USB Stick software overview
Figure 4-2. USB Stick software overview shows, in more detail, how different software and hardware
modules co-operate with each other. There are two main tasks of the USB stick board:
• receive the data from the MC13191 transceiver and store it in RAM buffer
• handle the USB module communication, decode and provide the data from the RAM buffer
These two are somewhat independent and the only common point between them is the accelerometer and
button data buffer in RAM. The RF software communicates with the Sensor Board and retrieves the latest
accelerometer data. This is stored in RAM and can be independently read by the PC application via the
USB link. The protocol employed on the PC side is just a subset of the Original ZSTAR that is build on
simple STAR protocol used in the original RD3112MMA7260Q demo. The protocol is described in
section Section 5.4, “ZSTAR3 USB protocol - Extended STAR protocol.
For the USB stick board operation, several MCHC908JW32 hardware modules are used: USB 2.0
Full-speed (USB), Synchronous Peripheral Interface (SPI), Keyboard Interrupt (KBI) and a General
Purpose Input/Output (GPIO).
GPIO
SPI
USB
RF
Protocol
Handler
LEDs
MC13191
RF modem
2.4 GHz
S
M
A
C
PC
Protocol
Handler
Sensors Data
USB
driver
USB
port