Support/hardware demonstration
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The demonstration system plays tones on loudspeakers.
A button allows to define the number of bits the sinewaves are coded on: This allows to talk of binary numbers.
The foreseen outputs are:
- a loudspeaker with a Digital to Analog Converter (DAC) and an analog amplifier
- a loudspeaker with PWM control and a simple class D amplifier.
Set-up
In order to build the demonstration, one needs:
- an FPGA board
- a power supply cable
- a flat band cable
- a HEB board with 4 switches
- an oscilloscope
- an oscilloscope cable
System
The following system is used to show digital electronic parts to students.
The block diagram is:
The FPGA design can be found in the HEI SVN.
Specification
To generate the PWM signal we have to compare the sinewave signal (tone) and a signal sawtooth signal whitch be generate with the counter.
The block diagram is:
With the block which has in entry (in put: PWM_out) and (output: C0, C1) we are going to get back the whole signal PWM_out.
The output C0=1 when PWM_out=0 and the output C1=1 when PWM_out=1.
The test block is defined below: