This is a port by Peter Cousens
to the PIC 16F84 of the
50Mhz
Frequency counter kit {originally available} from
Weeder Technologies . Since it uses
a base PIC that is easily programmable, and provides a usefull bit of bench
test equipment at very low cost, it makes an ideal PIC learning project.
If you don't want to spend the time on the PCB, collecting the parts or even
not programming the uP, you can order the kit (for a very resonable price)
from http://www.weedtech.com
News: Weeder Tech no longer makes this kit. They have moved on to a very
nice version that works with a local PC via the serial port for display and
control. It is also "stackable" for multiple counters at once or with other
modules for control and measurement of all kinds. See
http://www.weedtech.com for more
information. The original kit has been licenced to
Invent Electronics and Ken
has made some improvements and provides a very nice (closed source)
kit for $49
and a PCB for
$10 (prices as of 2004/03/05)
The result is a nice frequency counter that reads frequency from 1 Hz to 50 MHz and displays it on a 16 character LCD display. Auto-range feature provides floating decimal point and automatic placement of suffix (Hz, KHz, or MHz). Gate speed automatically decreases to one second below 100 KHz to display frequency with a resolution down to an amazing 1 Hz.
You will need:
Also:
See also:
Comments:
I have found a bug. When the display should show 255Hz, it shows 511Hz. 254 or 256 is fine, but not 255. The same goes for 511. It shows 767 instead.
767 -> 1023
1023 -> 1279
1279 -> 1535
1535 -> 1791
1791 -> 2047
2047 -> 2303
2303 -> 2559
2559 -> 2815
2815 -> 3071
I didn't bother to test more frequencies. I'm not very good at asm so I can't see why this happens. Maybe someone else has the solution. /Daniel
I've made a pcb for this circuit, I omitted the preamp as i'm using it for a homebrew function generator. If anyone wanna use this pcb I'd be happy to email it to you.
Thanks! I've posted the files here:
Frequency Counter
PCB
I have a fix for the pesky 8x2 displays that have been packaged as 16x1 displays. If you are only getting the first half of the display to work let me know. I'll send you the code that worked for me. (tested on model L1671 8x2 display)
Thanks! I've posted the code here: 8x2 LCD code +
Thanks much for the help!
Steve Brune says:
If you use the 16F84A for this project the software needs to be updated for bank switching to access the OPTION, TRISA and TRISB registers. The OPTION and TRIS commands compile with a warning in MPIDE but do not execute when burned in the 16F84A microcontroller.+
Questions:
file: /Techref/piclist/weedfreq.htm, 11KB, , updated: 2022/1/28 12:22, local time: 2024/11/9 15:17,
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