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USB or Serial port input device HELP Wanted

Posted: Mon Aug 13, 2007 2:37 am
by Modassar
i have a project to made which is the Employee Attendence system based on a RF circuit
each employee will have a separate RF transmitter & each has a unique id in binary (eg 10101100) the transmitter has 8 parallel lines. now i have configered each transmitter with a unique sequence of 1 & 0 which helps me to make a unique ids for each transmitter (eg if 1st line is high 2nd is low 3rd line is high 4th is low 5th line is high 6th line is high 7th is low 8th is low. i will get this value 10101100)
at the RF reciver end which ever byte is high the output will be 1 (that is 5 Volts) & if the byte is low the output will be 0 (that is 0 Volts). by this way i can control 8 relays at the reciver end. which ever parrel line is high the relay will trigger & where ever the line is low the relay will not trigger
so at reciver end i will get the same value 10101100
now i want to make a key pad & replace the buttons with the relay. so when ever the relay triggers it simulates as if a button is pressed thus transmittring the relay number to the computer & when a relay does not trigger on a certain button thee 0 zero value will be recorded
now this 10101100 which we recive have to be searched in a database to identify the employee & to mark his or her attendence.