I am getting strange behavior with this code: on the first press on a key (any key), the led blinks as it was supposed to; on the subsequent clicks of the same key, the led does not blink... To get the led to blink, I'd have to press some other key, and then any-but-this-"other" key, to which led blinks OK. If I comment out the goToSleep() call, add else Serial.write(key), and remove blinking, every keypress returns the result fine, so hardware-wise everything seems fine.
I am using Pro Mini, the code above, 2x2 keyboard with rows on 6,7, cols at 8,9, and the latest Keypad library (3.0). As far as I can see the only difference is the Keypad2 instead of Keypad library I have.
Does anyone else have the result like mine? It is driving me nuts the whole afternoon and evening. Can it be the non-blocking nature of getKey()?