USER MANUAL FOR HARDWARE REV 1.0
06-JUN-2019
PAGE 9
3.4
ANALOG TO DIGITAL CONVERTER
A MCP3208 is built into the system to provide
analog input capabilities with support for 8
channels with 12-bit resolution per channel.
Each channel is provided with some input
protection through a current limiting resistor and
a Zener diode. It is the user’s responsibility to
ensure the inputs are not over driven beyond a 5V
maximum input voltage to prevent damage to the
ADC unit.
vChannel A0 has a unique configuration to allow
for the use of a LM335 temperature sensor device.
It is recommended to use this channel last to
minimize potential confusion due to the unique
configuration.
When viewing the top of the board, the orange
arrow denotes pin 1 (A0) and increments up as
you move from right to left.
3.5
GPIO EXPANSION
As the repeater board consumes some of the
signals from the 40-pin header, an additional 8
pins are made available through a 16-pin header.
This header connects to PORT A on a MCP23017
IC. These pins are not protected from ESD or
overvoltage.
Caution should be exercised to ensure only
3.3V
logic levels
are used to connect to these pins.
The GPIO expander provides the option to include
pull-up resistors should your circuit need these,
but are not turned on by default, you will be
responsible for configuration of these pins if used.
When viewing the top of the board as shown, the
orange arrow denotes pin 1 (GND) and counts up
as you move from right to left.