Sorry for the delay in doing this testing. In order to measure current, the meter has to be inserted in series with the power source (battery). I was planning to do this by using pogo pins on the power switch with the Pokitto turned off. The meter would then conduct the current though it in place of the switch. Upon further examination, I decided that this would be a bit difficult and also wouldn’t include measurement of the RTC circuit, which is always powered up even with the switch off.
I decided to do it properly by disconnecting the battery and placing the meter directly inline with the positive lead. This took a bit more time.
I’ll give you the results first then, for those interested, I’ve included info on how I did this.
The programs provided don’t do much when supposedly sleeping. Current when the programs were running was close to 44mA and dropped to only about 43mA when sleep was selected.
One possibility is that the display may be drawing a majority of the power (especially the backlight) so the difference between the processor sleeping and running is small overall.
Another possibility is that the processor isn’t actually sleeping for very long overall. It may be waking up for some reason even when SleepTest.bin is in sleep mode.
Something to note is that when the SD card loader is running after power up, before the loaded program starts, the unit draws about 80mA. I’m not sure why this would be. Possibly, the processor does sleep a lot during program execution but there’s no sleeping in the loader. But that’s just speculation. It could be something entirely different.
Also, as a point of interest, about 2.7μA is drawn from the battery (by the RTC and maybe other stuff) when the power switch is off.
Here’s my Pokitto modification and setup used:
I unsoldered the positive battery lead and installed a bent header pin. I put a Dupont connector on the battery lead to allow me to reconnect it for normal use:
I cut a small notch in the bottom case half to feed wires though, below the PEX connector, that can be connected to an ammeter:
I made two extension wires to connect the board and battery lead to the ammeter:
Here’s the measurement setup. The μCurrent device presents a very low burden voltage and converts the current to a corresponding voltage that is measured by the multimeter: