Design Guide

Hardware Interfaces
A DIVISION OF TRIMBLE
26 Hardware Overview
The following table gives the Voltage and Current limits for all communication and control
interfaces:
Control Signal Specification
The module communicates to a host processor via a TTL logic level UART serial port,
accessed on the edge “vias”. The TTL logic level UART supports complete functionality.
The USB port supports complete functionality except the lowest power operational mode.
Specification Limits
Input Low-level Voltage 1.0 V max to indicate
low state; no lower
than 0.3 V below
ground to prevent
damage
Input High-level Voltage 1.9 V min to indicate
high state; 3.7 V max
when module is
powered up, no more
than 0.3 V higher
than Vout when
module is turned off
to prevent damage.
Output Low-level Voltage 0.3 V typ, 0.7 V max
Output High-level Voltage 3.0 V typ, 2.7 V min
Output Low-level Current 10 mA max
Output High-level Current 7 mA max