DIY Time Clock Project

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#1
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Hi there,

I have had a bit of a play with AVRs in the past, but am by no means an expert and my dad has asked about a time clock for his small business (6-8 employees) to keep track of employee hours. I found a few but they are very pricey and thought I would have a go at making one.

I have a basic idea that I would like to use an AVR or equivilent to do the processing. How I visioned it was that I would have a 12 key keypad and a 2x16 lcd.

The employees enter a code, 4 digits. The AVR then records the time and sends it to a text document on a PC, hooked up via serial probably. Either that or it stores the info onboard and is then downloaded weekly.

What I ask from you guys is to help me out a little and give me a few pointers as to which direction I should go, what AVR should I use, do I need any other components?

Here is a list of what I have so far:

An AVR (not sure which one yet)
A 2x16 LCD
A 12 key keypad

Thanks for helping me out,
Michael

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To keep it simple use DIP package components. For what you said, MEGA8/88 or similar is more then enough. However, it might be good to reconsider your project features and expand it "a little". Adding magnetic card reader could protect you from one employee entering numbers of others (alternative could be reader for used public phone smart cards). Whole design will fail if PC is down, so it would be good to record events in AVR, and then transfer all of them on PC demand. Use circular buffer to avoid always writing to same location in your permanent memory (or FRAM) and "tear it down" in time :-), or use FRAM. For these extra features it would be smart to have MEGA32 or bigger with extra storage. There are many other features that could be added but I guess it would be an overkill for an in-house project ;-)

Last Edited: Thu. May 28, 2009 - 08:01 AM
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avra wrote:
To keep it simple use DIP package components. For what you said, MEGA8/88 or similar is more then enough. However, it might be good to reconsider your project features and expand it "a little". Adding magnetic card reader could protect you from one employee entering numbers of others (alternative could be reader for used public phone smart cards). Whole design will fail if PC is down, so it would be good to record events in AVR, and then transfer all of them on PC demand. Use circular buffer to avoid always writing to same location in your permanent memory (eeprom or FRAM) and "tear it down" in time :-). For these extra features it would be smart to have MEGA32 or bigger with extra storage. There are many other features that could be added but I guess it would be an overkill for an in-house project ;-)

Thanks for your quick reply. I don't think that it is really neccessary to have a magnetic card reader as at the POS system they just use a pin and it would make it easy if I was able to just use the same thing.

I think that having the data stored onboard would be a better idea like you say. I have a ATMEGA16 so I will try a few things out on that first.

I was wondering if there are any tutorials on how to get a clock working that has date and time. I can't seem to get the search to work.

Thanks,
Michael

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Browse projects with keyword RTC and you will find plenty examples. DS1307 or similar will do the trick.

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Hi,

some parts are:
ATMEGA16L (flash+eeprom+rtc+uart)
8.000 XTAL
32.768KHZ XTAL
Backup Battery
MAX232 or HIN232
rs232 cable

also, please be informed that RFID / contactless cards are inexpensive now (about 1$ for each card and 25$ for its reader/writer module).

Regards
A.R.Khorasani
http://www.instrumentalanalysis.com

Regards
A.R.Khorasani
http://www.instrumentalanalysis.com