Running a Little Behind

With the project meeting agenda in the back of mind for tomorrow, I asked Battat to level with me about my progress, and, unfortunately, we are slightly behind on the project. To get this train back on track, I pulled into hyperspace, focusing on the hardware for the glue logic and compatibility between electronic components.

8-Pin Decoder mounted on PCB board
 under a magnifying glass
We were fortunate enough to receive our packages from Adafruit and the other pieces this week early on. I immediately dived into some largish-scale soldering with the mux eval boards. I made the ribbon cable for the divider circuit that I started wrapping up last week and then soldered the cable's ends to the eval board. Battat started placing some of the capacitors and resistors on the board today; I'm glad I did because that might have gotten messy without some guidance. small-scale soldering with these miniscule pieces, and Battat showed me some techniques in creating better joints with the iron tips. I definitely have become more comfortable with the magnifying glass and microscope now. After cleaning up the eval board, I started on the glue logic pieces, mounting them on the PCB board and soldering the pins too. The binary counter (74LVC161) and 16-pin decoder (SN74LVC139A-Q1) weren't too bad: they were more challenging than the last task, with ensuring the pins were perpendicular to the PCB board, but I could still see where I was going. On the other hand, the 8-pin decoder (SN74LVC1G139) was a doozy. I couldn't see where the solder was going. Once Battat showed me a few tips and after several attempts at making clean, strong joints on this tiny component, I finally got it and then soldered on the pins to the board.

It was now time to test out the glue logic -- or the counter circuit discussed in my presentation. Ensuring I knew what each pin represented, I started making connections to the 8-pin decoder from the binary counter and added LEDs to each of the decoder outputs as a visual aid for HIGHs and LOWs. Using a function generator, I added a 1 MHz clock and let my baby run wild. I had to slow down the frequency as I needed to count for consistencies in the HIGH and LOW times, but, once I did, I immediately noticed one output had a much shorter cycle than the others. That is a problem for what we need. I then set up the 16-pin decoder to the binary counter and wanted to see how it ran in comparison. The decoders were synchronously in error: it seemed 3 parts were equal in time while 1 piece of the clock cycle was cut short. Making a detailed timing diagram might help us see the source of problem and it is possible that our logic is off. Once we debug the counter, then it would be beneficial to see the limits to how fast we can run a clock on a breadboard without fail and then test the multiplexer (once we surface mount all the pieces to the eval board). I'm meeting with Dr. Phillips tomorrow and we can pick his brain for electronics insight on the problem and where to look next. In just a few days, I've picked up pace and gotten things partially back on track. Battat will be out next week and I'll be doing most of the work then by myself. Here goes everything...

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