Hardware/Parallelport/heb microphone
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Revision as of 15:02, 18 May 2018 by Francois.corthay (Talk | contribs)
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The board was designed for the SEm VHDL FSM lab.
It has a beeper which can emit a Morse code signal and a microphone for receiving it.
Version | Photo | Schematics | Stock |
---|---|---|---|
V1.1 | ![]() |
HEB-microphone Schematic PDF | 10 fully mounted |
Beeper
The beeper is driven directly by a digital I/O line.
Microphone
The microphone's output is amplified and connected to an ADC. The amplified signal is also triggered in order to deliver a simple digital input to the FPGA.
Setup
The microphone's output is quite small. It is first fed to a fixed amplifier through a passive RC highpass.
The buzzer/microphone couple have 2 resonant frequencies: one at 3 kHz and the other at 4 kHz.
The trigger is a Schmitt trigger. When there is no signal, the trigger output can be as well low or high.