Digital Integrated Circuit Tester ( Using AT 89 s 51 Microcontroller )

The Digital Integrated Circuit Tester implemented as in this paper is capable of testing 14 pin Integrated Circuits (ICs) of 7400 series. First, the system welcomes the user and asks the user to enter IC number. It takes the last two digits of the IC no. of the IC to be tested as input from a 4x3 matrix keyboard which is implemented by 12 push buttons. It then checks the IC(in the 14 pin socket) as per the IC no. and gives output at an 16x2 Liquid Crystal Display (LCD) by displaying “GOOD” or “BAD” next to the corresponding gate no. In case of wrong IC no. input or more than two digits is tried to be entered, an error signal is generated and the LCD displays “ERROR”. „Reset‟ key is used to reset the system and to go back to the welcome screen. „Enter‟ key is used to give signal to the system to the start the checking process. Power ON LED is provided to indicate when the system is powered. The heart of the system is an ATMEL 89s51 microcontroller which is programmed for detecting keystroke, deciding which IC to check for, give inputs to test IC, check the outputs of the test IC and display in the LCD as mentioned before. Programming is done in assembly language for optimum utilization of memory space available. As the more effectively available memory is utilized the more number of ICs can be tested by a single controller system. In the assembly language program (ALP), each gate in the IC is checked for all the input combinations possible e.g. 00, 01, 10 and 11 input for two input gate ICs. The logics for checking different ICs are in sequence of their IC no. one after another. A 0.25 second key debounce delay is provided in ALP. The device was designed at Centre for Electronics Test Engineering (CETE), Kolkata. Keywords— AT89S51, Effective Memory Usage, Embedded Systems, HD44780, Integrated Circuit Tester.