When I uncomment
#define SHOW_CAL, it’s then too big for an Uno:
text section exceeds available space in boardSketch uses 33072 bytes (102%) of program storage space. Maximum is 32256 bytes. Global variables use 1316 bytes (64%) of dynamic memory, leaving 732 bytes for local variables. Maximum is 2048 bytes. Sketch too big; see http://www.arduino.cc/en/Guide/Troubleshooting#size for tips on reducing it. Error compiling for board Arduino Uno.