MSP432 LPM3 (deep sleep) mode

I got MSP432 LPM3 mode (deep sleep) working. Actually everything else was OK, but it seems that RAM retention was not enabled by default. After adding

MAP_SysCtl_enableSRAMBankRetention(SYSCTL_SRAM_BANK7);

to startup things look much better (obviously, as RAM contents was lost before). I was able to run Pico]OS test application with EnergyTrace+ monitoring enabled:

 

This shows that CPU is spending about 5 seconds in active mode and 5 seconds in sleep, which looks what one would expect from this application.

 

When looking at power graph it is possible to see that HZ is 1 second, there are short spikes when WDT interrupt that drives Pico]OS clock is processed.

Overall statistics show that about half of time is spent in active mode. However, almost 70% energy is used in active mode, mainly because it turns the led on.