Oh my! Some pretty nasty self-imposed restrictions there Hank'.
There are smaller switches (see below, just left of the machined socket). And if you think about it, that tri-color LED actually has four states (off, red, green, and yellow).
Good luck on your project.
** added **
Someone just wrote to ask about the driver for that mux'd switch & LED drawing so I'll add it here if nobody minds. And sorry for the C code (I don't have PBP)...
The routine sets the four pins to inputs to read the switches. Standard 'parallel' switch state logic filters out all but a "new press" state while ignoring the other three states (for each switch). 1-of-N logic (only 1 mode on at any time) dictates that we save the "new press" pattern as the new "mode". Since a pressed switch could short out a pin that is set to output '1' we cannot turn off the inactive LEDs by outputting a '1' and so we leave those pins tri-stated (RC3..RC0 output latch bits are maintained at '0').
Code:
/* *
* isr debounce & switch state management (1-of-N switch logic) *
* using 8 to 32 msec interrupt intervals *
* *
* swnew ____---____-----___ new switch sample *
* swold _____---____-----__ switch state latch *
* delta ____-__-___-____-__ changes, press or release *
* newhi ____-______-_______ filter out new release bits *
* */
trisc |= 0x0F; // set RC3..RC0 to inputs
swnew = ~portc; // sample active lo switches
swnew &= 0x0F; // on RC3..RC0 pins
swnew ^= swold; // changes, press or release
swold ^= swnew; // update switch state latch
swnew &= swold; // filter out new release bits
if(swnew) // if "new press"
mode = swnew; // save 1000,0100,0010, or 0001
trisc ^= mode; // light the correct mode LED
)
Originally Posted by Mike, K8LH
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