The PCB must be mounted floated, otherwise key presses don't work reliable. Connect pins 3 and 4 on connector P1 for 16-pin button mode. Smaller keypads with less pins may work, but are not tested.

Saves in EEPROM the numbers of hours since transition, so that if Arduino is restart it looses at most 1 hour. The 1 hour resolution is a tradeoff betweem accuracy ...

CNET staff -- not advertisers, partners or business interests -- determine how we review products and services. If you buy through our links, we may earn a commission.

If you want to be kinder to your eyes while gawping at a digital screen all day, you could opt for E Ink. But that's not as color-rich as LCD, which is why TCL developed NXTPAPER. The 11 Plus tablet ...