LPC55S69 freertos_tickless example not working

[chetferry]

I am trying to run the freertos_tickless demo on the LPC55S69 board.  The processor is drawing 7.15 mA of current while the demo is running.  So I think something is not right.  I was assuming this demo is supposed to put the processor to sleep?  I am measuring the current with a Fluke 189 meter with the leads connecting the pins on P12 and R91 removed.  I am quite certain I am correctly measuring the current to just the processor.  Am I doing something wrong?  Thanks.

[xiangjun_rong]

Hi, Chet,

If you want to measure the current of the LPC55S69 on board, I suggest you run the example code "power_manage_lpc" example, because the LPC55S69 remains low power mode for a long time so that you have enough time  to measure. In the example, it wakes up by either by pressing a hardware button or a long time RTC waking up interrupt.

The freertos_tickless example enters/exits low power mode frequently, it is difficult to get the correct aperture to measure the current in low power mode by a current meter.

Hope it can help you

BR

XiangJun Rong

[ErichStyger]

Hi Chet,

no, tickless idle does exactly what the name says: it uses no ticks during idle.

See Low Power with FreeRTOS: Tickless Idle Mode | MCU on Eclipse  for the technical implementation and details.

So it reduces the tick frequency so you get less interrupts and you can stay lower in low power mode (if you are entering low power). How much you will save depends on your tick frequency and application load, but you already should see some little savings if you go into WFI mode.

I hope this helps,

Erich