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.


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

For the DAC solution, one additionally needs:

  • a flat band cable
  • a HEB DAC board
  • a loudspeaker board
  • an RJ45 cable
  • a power supply adapter for the loudspeaker board

For the PWM solution, one additionally needs:

  • a loudspeaker box with the amplifier on the back side
  • a C-shaped FPGA board mezzanine
  • an additional oscilloscope cable


The following system is used to show digital electronic parts to students.

hardware demonstration system

The block diagram is:

block diagram

The FPGA design can be found in the HEI SVN.


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:

pwm modulator

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:

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