User Manual

ZSTAR3 Sensor Board Description
ZSTAR3 Reference Design Manual, Rev. 0.1
Freescale Semiconductor 3-21
Preliminary
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3.3.1 Sensors power supply
Sensor are powered by IO pins of microcontroler. This can be done, because sensors consumed less than
0.5mA Three output pins together are used for analog VDD supply pin of sensor. This option hold down
dynamically changes of voltage with different current consumption of sensor.
Main feature of this solution is unbeatable currunt when complete board is in deep sleep mode (all board
concum less than 1µA). Thus by this option the ZSTAR3 hasn’t to using sleep modes of sensors.ore details
in section 3.3.1/3-Sensors power supply-21
3.3.2 Analogue sensor connection
The MMA7360L Sensor outputs are connected to AD0, AD1, and AD2 inputs to analog-to-digital
converter via RC filters formed by internal resistors in sensor and C13, C14, C15. These are recommended
to minimize clock noise from the switched capacitor filter circuit inside the Sensor. Once the software
filtering (also described in ) is employed, these RC filters may be completely omitted.
The MMA7360L provides four next digital signals g-select, Self-test, 0g-detect and Sleep. All these pins
are also routed to microcontroler, but only g-select and 0g-detect are use by software.
3.3.3 Digital sensor connection
The MMA7450L sensor are control by digital interface and two interrupts pins. Digital interface take a 4
wires, that provides both interfaces - IIC and SPI. These pins are routed to general IO pins and IIC
microcontroler module, but board doesn’t provide external pull up resistors and thus can’t be used IIC
module. This option saving a energy of battery in deep sleep mode.
• pin 13 - SDA/SDO/SDI - IIC data, SPI data input/output
• pin 12 - SDO - SPI data output
• pin 14 - SCL/SPC - IIC clock, SPI clock
• pin 7 - CS - Chip select
Two interrupts pin called INT1/DRDY and INT2 are routed direct to KBI module of microcontroler. By
this option software can be build on interrupts events. Signals use internal pull up resistors in
microcontroler.
• pin 8 - INT1/DRDY - interrupt 1 output, Data Ready output
• pin 2 - INT2 - interrupt 2 output
When is digital sensor connected, then on footprints C13, C14 are placed 0R resistors. These two resistors
grounded pin2 and pin4 of digital sensor.
3.3.4 BDM (Background Debug Mode) Connections
A J2 connector is a non-standard footprint primarily intended for in-factory programming and testing via
“spring-needle” type of connections. The J2 connector carries all standard signals for Background Debug
Mode communication so if required, one may solder wires and a standard 2x3 pins 2.54mm (100mil) pitch