19.8.5. Using Deep Sleep on LPC1114
While we can get to just ∼1 mA operation, this is not good enough for some of the ULP applications. You might notice that so far the deep sleep mode feature has not been enabled in the previous examples. To use deep sleep mode, the program code quite a few changes because of several restrictions on the LPC1114 deep sleep mode support:
• In deep sleep mode, the only available clock source is the watchdog oscillator. It is very low power, but can have up to ±40% tolerance of the clock frequency value.
• In deep sleep mode, the timer interrupt will not operate and it can only be wake up by one of the Wake-Up interrupts.
There are a couple of other areas we need to take care of:
• Due to the inaccuracy of the clock ...