Posted on 17 Jun 2008
In counter mode it provides 1Hz resolution up to 100Mhz. In timer mode maximum resolution is 0.0000001 Hz up to 1Hz. Resolution is reduced by one digit for each additional decade. Multiple frequency updates per second by employing a sliding window for calculation.[more]
Posted on 18 May 2008
An AVR controller can be used as a counter, although it is a bit more involved than with a PIC. The reason is that a PIC (at least the 16F84) has an asynchronous counter input. This input will handle frequencies up to app. 40 MHz. AVR’s have a synchronous counter input which is sampled with the clock frequency, so it cannot measure frequencies over half the clock frequency. So, when using a 4 MHz clock, input frequencies must be lower than 2 MHz. Use 40% of the clock frequency to be on the safe side.[more]
Posted on 11 May 2008
The whole counter design is based on the PIC micro-controller 16F876A. The latter includes several peripherals and just a few of them are used in this project. The most important in this project are two internal, hardware counters/timers called TMR0 and TMR1. The TMR0 timer generates very precise interrupts every 100 microseconds (10kHz) from the 20MHz clock/reference. All required timings for the counter timebase are simply integer multiples of this basic period. [more]
Posted on 11 May 2008
Frequency counter built by Wayne McFee. This is from IK3OIL’s web site, and the cost of the counter was about $2, minus the display, which was about $7.Design and Code by Francisco IK3OIL.McFee writes:
This frequency counter was mentioned on the QRP-L mailing list.
I offered to put up some more information on the counter on this web page.
I have not built one (yet) nor do I have any further information than what is here.
[more]
Posted on 11 May 2008
This document describes the construction of small frequency counter with a cheap PIC microcontroller and a few seven-segment LED digits. The main features of the frequency counter are: frequency range 1 Hz … 50 MHz (prototype worked up to 60 MHz but this exceeds the PIC’s timing specifications) ,four or five digits resolution (display for example x.xxx kHz, x.xxx MHz, or xx.xx MHz) ,automatic range switching with different gate times ,optional addition or subtraction of a frequency offset (programmable) ,optional preamplifier for the input signal ,can be built on a single-sided ‘breadboard-style’ circuit board ,firmware available for common-cathode as well as commom-anode displays ,
very low component count: a PIC 16F628[more]
