Onboard microphones, Digital output port leds, Switch input port – National Instruments Signal Processing Engineering Educational Device NI SPEEDY-33 User Manual
Page 19
Chapter 2
NI SPEEDY-33 Functional Description and Interface
© National Instruments Corporation
2-7
Onboard Microphones
Two onboard microphones (U2 and U5) can be used in applications
requiring audio input or involving audio signal phase difference
measurements. When the microphones are used, the input gain level of
each microphone should be set to the microphone level setting described
in the
section.
Caution
Ensure that line level audio signals are not connected to the audio input when the
NI SPEEDY-33 is configured for microphone level. It is possible to damage the audio input
circuitry by overdriving the input.
The onboard microphones are directly connected to the audio input
conditioning circuitry, unless an external microphone is connected at
the stereo input port (U11), as described in the
section. If an external microphone is connected, the onboard microphones
are disconnected from the input circuitry by mechanical disconnect.
Digital Output Port LEDs
Eight memory-mapped LEDs are located on the NI SPEEDY-33 for
general-purpose output. The LEDs are enabled by writing a 1 to the
appropriate bit of the LED port. The LED output state is echoed on pins on
the simple expansion digital I/O connector (J11), as described in the
Expansion Digital I/O Connector
Switch Input Port
There are eight memory-mapped general-purpose switch inputs on the
NI SPEEDY-33. These switch inputs are accessed by the DSP through
reading the appropriate bit of the switch input port. The switch inputs are
connected in parallel to pins on the simple expansion digital I/O connector
(J11). All switches should be in the OFF (open) position when connecting
the expansion digital I/O connector, as described in the
section.