problem regarding IC74HCT373

Hi , Actually I Wanted To Know That I Am Designing This Circuit Of Access Control System With Lcd Display But I Am Not Able To Know The Function Of The Ic74hct373 So Please Tell Me As Its Very Urgent View attachment 6.pdf Kindly Help Me

ATMMEL said:

Hi , Actually I Wanted To Know That I Am Designing This Circuit Of Access Control System With Lcd Display But I Am Not Able To Know The Function Of The Ic74hct373 So Please Tell Me As Its Very Urgent View attachment 25744 Kindly Help Me

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hi,
In this circuit they are just used as Buffers for the MCU data lines.

The keypad is poorly designed in this circuit. You only need 7 pins for a multiplexed keypad (this circuit uses 12 pins).
You can eliminate both of the 74HC373's and just use the micro controller pins as inputs or outputs.

Connect the keypad like this:**broken link removed**
although this is a 4x4 keypad, you will only use 7 pins instead of 8. You would make the rows inputs and check each of the columns one at a time to see which key is pressed. There is lots of free source code available.

Do you have the software for this circuit? If not you can find lots of sample code if you search google.