How to measure signals off a memory IC on an oscilloscope

Monday, May 12, 2014

Q. I am studying Lesson 6720, Semiconductor Memory Interfacing. The lesson describes the signals going to the different pins of the memory IC. I would like to know if there is a way I can view these signals on my oscilloscope.

A. One of the problems with viewing the waveforms is that they appear for only a microsecond or so, and are mixed in with signals for other parts of the memory. They may only appear once during the entire time that the program runs. One way to view the signals is to put the 6809 in a tight loop with a short endless loop program.

By modifying the loop program, you can repetitively read or write to the memory chip, and view the timing of the signals on the data and address buses. Connect the EXTERNAL SYNC input of your oscilloscope to trigger on the Chip Select signal on the memory chip. A good sweep speed to use is 1 us/ div. You can then view the signals on the address and data buses, and on the Output Enable and Write Enable pins.

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