Analog Logic Inputs; Logic Outputs - Polycom SoundStructure C16 Design Manual

Analog Logic Inputs

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.
An example of connecting a volume knob potentiometer for volume control is shown in the following figure.
In this figure, the volume knob has three connections – one to the +5V connection, one to ground, and the
third, the wiper of the potentiometer, will be connected to the analog gain input. As the knob is turned, the
voltage measured varies between 0 and approximately 5V. The values measured from the analog logic gain
input varies from approximately 0 to 255.
Connected Volume Knob Potentiometer for Volume Control

Logic Outputs

SoundStructure devices implement logic outputs as open collector circuits. The open collector design,
shown in the following figure, makes it possible to drive LED's and relays with minimal additional circuitry.
Please note that only positive external voltages, such as the +5V supply on pin 1, should be used with the
logic output pin. Each logic output pin is capable of sinking 60mA of current.
Polycom, Inc. 250