I had been using Microchip micro-controller from its 8-bit series up to 32-bit series. Recently I have
the opportunity to use ST Micro 8-bit micro-controller STM8S series. It has similar feature as Microchip, not all, but almost similar. Good thing is that it has a CAN (Control Area Network) Bus hardware module for such as a small MCU and furthermore its pricing is as low as 12F or 16F Microchip.
For this article, I would like share on the low power management feature which I think quite cool. Some MCU has different sleep modes such as Idle, Sleep, Deep Sleep, Deep-deep Sleep (or dead, maybe not waking up at all....just joking). STM8S has the feature known as "Active-Halt-Mode". At a glance, I thought Halt Mode consumes lower power but actually Active-Halt-Mode is much much lower. During this mode, you could even turn off the internal voltage regulator, clock oscillator, peripheral, power to internal flash memory, etc....hmmm, maybe can consider "Dead" :) The only way to wake up the MCU is via external I/O interrupt or a timer known as "Auto-Wake-Up (AWU)". Before entering the Active-Halt-Mode, the AWU is enabled prior going into Halt Mode. User has the option to select the time interval for the MCU to wake up and do something. User has the option to wake up, service the AWU interrupt, then back to sleep or back to main then back to halt mode. During Active-Halt-Mode with all turning off, one could achieve around 66 micro-Amp.
In the next time, I will share some of the code on how the Active-Halt-Mode is written in the IAR C-compiler...free version, of course :)
