38 lines
1.3 KiB
Markdown
38 lines
1.3 KiB
Markdown
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TinyAdder
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========
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TinyAdder is a 4-bit adder built on the TinyFPGA BX. It connects four
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slide switches (I wanted actual toggle switches, but that's how it goes)
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to a pair of 7-segment LCD displays.
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Code organisation
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-----------------
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Currently there are two modules:
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+ SegmentLCD: a little awkwardly named due to the naming constraints,
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but this takes a 4-bit input number and outputs a 7-bit output. The
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hookup requirements are described in the module comments.
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+ TinyAdder: This is the top-level adder.
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Hardware revisions
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------------------
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+ rev1 (2018-12-22)
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+ rev2 (2018-12-22): realised that the LCDs were missing resistors;
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I had been looking at a tutorial that used a shift register; the shift
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register apparently had an internal current limiter so I assumed the
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LCDs didn't need them. This was wrong. Fortunately I was able to cancel
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the rev1 order before it went out.
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+ rev3 (2018-12-28): after breadboarding the push button, I realised
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I'd messed up the schematic (and accordingly, the board) by wiring
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both ends of the push buttons to Vcc, which... isn't very useful at
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all. I fixed it, but not before the rev2 was sent to the fab.
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TODO
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----
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+ I'd like to have the two displays show the two numbers before adding
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them. The 'hi' display could show the first addend, and the 'low' could
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show the second addend, with live updating.
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