Electronics > Microcontrollers

What are you doing with Padauk chips you bought?

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Nominal Animal:
PMC251 might be suitable for HID buttons and rotary encoders, using SPI (chain) as a shift register for accessing their state, plus a separate latch signal for sampling all in parallel.

Essentially, PMC251 can be made to run two "cores", interleaved, on every other system clock cycle; each "core" has their own program counter, stack pointer, accumulator, and flags.  One "core" would monitor the encoder state(s) and latch signal, and the other "core" handles the SPI shift register.  (The latch transition simply preloads the SPI shift register with the encoder state.)  Running at 8 MHz, this should be fast enough so that no transitions are lost and debouncing can be done in software.

At €0.17 or less apiece (with each capable of handling two encoders or seven buttons), it'd make a nice way to make human interface buttons and encoders for a number of gadgets, if one designs the data stream sensibly.  Changes since last latch might be most useful (with buttons reporting both press and release events so that a button press is not lost even if it happened entirely between two consecutive reads), because it'd allow encoder acceleration profiles also, and the per-encoder state wouldn't need too many bits.


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