I am looking for a circuit that will activate a trigger every 24 hrs and count the pulses and
display the count using 3 or 4 7 segment led displays (the display will need to be resetable).
I need something that is fairly power efficient as it would probably be battery operated. Any suggestions??
TIA
There are several microcontrollers that have very low current usage. Texas Instruments MSP430 series,
some Atmel AVRs, and Microchip PICs, etc.
7 segment led displays are great users of current, so an LCD would be my preference.
The AVR Butterfly is a cheap (~$30) development tool that has on-board an ATMega169 microcontroller,
4Mbit dataflash, 32KHz crystal, speaker, 100 segment lcd, light and temperature sensors and a battery,
all on one credit card sized board. I think Soanar handle it.
Dontronics has a MSP430F2131 (8K program flash, 256 bytes data and 256 bytes data flash) header
board for about $20. Just add a cheap off-the-shelf 16x2 LCD and some buttons. Those should be
banging around in any engineer's or technician's box-o-bits. Code examples for the MSP430 series
are freely available on the 'net, and it's supported by the Yahoo MSP430 group.
For such a simple application, tools such as the Butterfly or the 'F2131 might be considered an overkill,
but when you have all (or nearly all) the hardware on one small cheap board, it makes it difficult to
ignore them, especially if there won't be many units in the field.
One thing you didn't mention, is how many pulses per 24 hour period you are expecting.