Polycom SoundStructure C16 Design Manual page 65

Logic Inputs
All digital logic inputs (logic inputs 1 - 22) operate as contact closures and can be connected to ground
(closed) or not connected to ground (open). The logic input circuitry is shown in the following figure. The
default value for logic inputs is 1 due to the pull up resistor. The value for the pin changes to 0 when the pin
is shorted to ground. The value of the logic pin is read or written with the digital_gpio_value
parameter. See Using Events, Logic, and IR
details.
Logic Input Circuitry for SoundStructure Devices
SoundStructure Logic Input
Logic
Status
Analog Gain Input
The analog gain inputs (analog gain 1 and 2) operate by measuring an analog voltage between the analog
input pin and the ground pin. The maximum input voltage level should not exceed +6 V. It is recommended
that the +5 V supply on Pin 1 be used as the upper voltage limit.
The next figure shows the analog gain input pin and the associated +5 V and ground pins that are used with
the analog gain input pin. The analog voltage on the analog gain input pin is converted to a digital value via
an analog-to-digital converter for use within the SoundStructure devices. The maximum voltage value, that
Polycom, Inc.
and Appendix A: Command Protocol Reference Guide
3.3V
Logic Input Pin
Logic Pin 25 (Ground)
for more
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