Design Overview
This design converts the
As well as providing the basic instructions to use the frequency counter, this document provides details of the Direct Digital Synthesis (DDS) techniques used in the design such that the can be transplanted into your own designs. PicoBlaze is used to provide the human interface and perform so high precision calculations which are passed to a simple but high performance (200MHz) frequency synthesizer formed from pure hardware and two Digital Clock Managers (DCMs). The lower line of the LCD display provides the information passed from PicoBlaze to the hardware which means that you can use this design with your board to determine the exact values required to implement a fixed frequency synthesizer without requiring PicoBlaze, the knob and LCD display. On this board the technique provides a convenient alternative to fitting a special oscillator in the IC16 socket and it may proves a cost effective solution for many real product applications too.
Load it now – it only takes 30 seconds!
It is recommended that you try this to become familiar with what the design does (operating instructions on the next page).
As well as the source design files, a compiled configuration bit file is provided which you can immediately download into the Spartan XC3S500E device on your board. To make this task really easy the first time, unzip all the files provided into a directory and then….
double click on ‘install_frequency_generator.bat’.
Assuming you have the Xilinx software installed, your board connected with the USB cable and the board powered (don’t forget the switch), then this should open a DOS window and run iMPACT in batch mode to configure the
Spartan XC3S500E | 50MHz Reference | |
Crystal Oscillator | ||
|
Press and rotate knob | DDS control values |
to set frequency | (bottom line) |
Phase
Accumulator
Test Point
Copy of Output
Frequency
LEDs indicate
frequency
editing mode
Frequency display
(top line)
Frequency Generator for the