The sleep mode on PIC32MZ proved itself a nut quite hard to crack. A ton of registers to control power to this or that, and still no single solution that simply puts the chip into sleep mode. Microchip haven't learned their lesson yet, apparently.
Anyway, the work on this is on.
Rittle's main purpose is educational and as such it includes everything that a student would need to understand embedded processing. The environment is command line with a line editor that is not too easy and not too hard to learn. Compilation of a high level language lists low level pseudo-assembly that can be traced during execution.
Next stop - displays.