Tuesday, September 20, 2011

A Little Bit of Bread-Boarding

I finished the simulation a while back but have been busy so no new posts recently.  I am still trying to find the best way to upload the logisim schematic, any suggestions in that area would be appreciated. Here is the Logisim source file!

Screen Shot of Working Simulation

I noticed when I was working with logisim the D-flip-flops (DFF) I created using NAND gates always started out in an error state.  It took a full clock cycle for them to correct this then they functioned properly until the next reset.  I have a trigger using a DFF that must start low so I needed to build it to make sure it starts low.  Most of my NAND chips are on order but I did find one left over from a project I did a few years back.

Initial Power On DFF from NAND

As you can see from the picture the /Q line is active on power on.  The white wire is the D input and the brown wire is the Clock.  After clocking in a HIGH:

DFF from NAND HIGH state

It works!  I always get excited when I see LEDs light up when they are supposed to light up.  This proved that the DFF does start in the LOW state and does work.

I have started working on the LED matrix, specifically on how to defuse the LEDs and make them into nice looking squares... but more on that in the next post.

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