Low and High pass filter designer for implementation in VHDL

This post is about digital low and high pass FIR filter design in VHDL.
Implementing high/low pass filter in the digital domain has a lot of benefits compared to implementations in the analog domain.
The VHDL code for an implementation using convolution is provided. To design the filter, a MATLAB/OCTAVE script was written, in order to derive the filter kernel. The kernel can directly be copied into the VHDL code and can be tested with an VHDL test bench.

The whole description of the project can be found under:

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Breakout board for the DAC900E a 165 MSPS @ 10 Bit DAC

This breakout board helps me to interface my FPGA with the DAC900E from Texas Instruments.
The DAC has 165 MSPS and 10 bits which is quite some speed.
The combination FPGA and DAC opens up for experiments with digital signal processing, like making a direct digital synthesizer (DDS), digital modulation and many more. The DAC is fast enough to use it in the TX part for a shortwave radio without any analog mixer required.

A detailed description can be found:

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Arduino controlled Frequency Generator 1kHz – 68 MHz

This project is a description of how to build a signal generator with an output frequency from 1kHz to 68 MHz.
The frequency generation is handled by a small Programmable Oscillator from Linear Technology the LTC6903.

The control of the Programmable Oscillator is done by the ATMEGA328 microprocessor, the output frequency is shown on a 7 segment display.

The hole description can be found here:

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Design of a FPGA PCB including USB2.0 interface and two 80 MHz ADCs

This is my most advanced homemade PCB design until now.

The PCB contains a EP3C5E144C8N Cyclone III FPGA from ALTERA, two 8 bit ADCs AD9057 from Analog Devices @ 80 MHz, a FTDI USB2.0 controller and many other things.

The PCB was designed in order to evaluate if such a design is feasible with home fabrication. And it is.
The two ADCs open up many possibilities for signal processing, even though the FPGA is probably not the most powerful.

The full description can be found on:
Design of a FPGA PCB including USB2.0 interface and two 80 MHz ADCs

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PCB tinning including VIA soldering

This is some method I found on the net for solving the problem of protecting the cooper of self produced PCBs.
What is done is the PCB is tinned before parts are soldered on it.

I discovered that this was exactly what I was looking for in order to solder a lot of small vias on more advanced PCBs with vias under the ICs.

In short: etch the PCB, drill the holes, make the vias, tin the PCB and you have a nice double sided PCB for soldering parts on 🙂

A more detailed description:

PCB tinning including VIA soldering

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Raspberry Pi as a Macro Camera

This post describes how to use the Raspberry Pi camera as a Macro camera.

I use it to do control checks when soldering PCBs with very small components.

It is very convenient since I get the picture directly on the screen, I like it more than using a microscope as long as no huge magnification is needed.

Simple to do and it makes life much easier in terms of checking small things! 🙂


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FTDI FT232H USB 2.0 FPGA extension for the Altera DE0

This is a PCB design using the USB 2.0 IC from FTDI, FT232H – Hi-Speed Single Channel USB UART/FIFO IC, to connect it to the GPIO port of the Altera DE0 development board. The design should also work with other development boards which have a 40 pin connector like the DE2 and others.

This board is to test the implementation of the USB 2.0 controller directly on the PCB for future projects, instead of adding the UM232H evaluation/development board on top of a IC socket as done in earlier projects.

The full project can be found on:


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