Wavecom GR64 Application Note - page 4
1
Introduction
The GR/GS64 family of Wireless CPUs is designed to provide a rich and flexible set of
physical interfaces. These interfaces allow the application designer to integrate
GR/GS64 Wireless CPUs into the widest possible variety of applications and still meet
cost, power and size constraints.
GR/GS64 general purpose input and output (GPIO) pins represent the simplest of
digital interfaces—single line digital signals. GPIO pins can be used to control or
monitor devices such as relays, contacts, actuators and lamps with appropriate signal
conditioning. GR/GS64 Wireless CPUs provide as many as thirty-three GPIO pins.
GR/GS64 Wireless CPUs also provide up to three analogue-to-digital converters.
These convert analogue voltage levels to digital measurements. With appropriate
transducers, applications can use the measurements to monitor a wide variety of
physical conditions like temperatures, pressures or fluid levels.
1.1 Logic Interface Voltage
All GPIO interfaces are referenced to the voltage level available on system connectors
VREF-pin, unless otherwise is stated in the units Integrators Manual.
GR/GS64 Wireless
CPU type
VREF Direction
VREF Voltage Level
GS64
Output from Wireless CPU
1.8V
GR64001
Output from Wireless CPU
2.8V
GR64002
Input to Wireless CPU
1.8V – 5.0V
Under no circumstances can a logic signal exceed VREF. Level translators must be
incorporated if the application logic voltage is different than that of the Wireless CPU.
Failure to heed to this requirement can lead to unexpected behaviour and may
permanently damage the Wireless CPU.
Examples of possible level translators to use consist of, but are not limited to:
Maxim
MAX3000 family
ST ST2378E
APPLICATION NOTE
GR/GS64 General Purpose and
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Alternate Function I/O
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