7-digit frequency meter/digital scale
The construction is based on Microchip Application notes
No 590 (LED display multiplexing) and
592 (frequency meter).
The prototype was developed with common cathode LED display.
Power consumptions with small calculator display: 2.5V/9mA, 3V/13mA, 5V/35mA.
Hardware is very simple:
It contains :
Note:
"Calculator display" means minimum 7 digit LED multiplexed display.
Both common cathode and common anode can be used. Software is written
for common cathode display. For common anode displays it requires very
slight software and hardware modification.
The counter uses internal prescaler of PIC as low byte of counter,
TMR0 as middle byte and some register as high byte of counter.
Some ideas were taken from "Simple low-cost digital frequency meter using a PIC16C54"
(frqmeter.asm) written by James Hutchby, MadLab Ltd. 1996 |