This is a read-only archive of an earlier blog posting. Reasons for the
change are at http://blog.sensicomm.com.
The permanent version of this post - with comments (if any) - is at
FPGA frequency counter code.
An FPGA project that does something
useful: implements a frequency counter using the Xilinx Spartan 3AN
development board. Basically consists of two counters and the AX8
uC core. The first counter generates a 1 Hz timing signal from the
on-board 50 MHz crystal oscillator, and the second counter counts
the signal under test. The AX8 core runs a simple program that
reads the count value and formats it for display on the LCD.
The attached image is counting the frequency of a VEX RC
transmitter using a 75.97 MHz crystal. The measured count is
75.971459 MHz, which is within 0.002% of the expected value. The
development board uses an xtal oscillator marked AGXO-751L 50.000
A. I found a datasheet at www.inysa.es indicating that A versions
are 100ppm, or 0.01%, so the measured value is well inside the
I'll be posting the code when I get it
Comments on blogspot.com
To make or view comments, see the original post at