Hi,
While testing, I ran into multiple problems when measuring the current consumption with the PPK 2 on the nRF52833 dk.
For all measurements the Blinky + Bluetooth demo program was used.
1.
When the PPK is used as a source, connected the upper pin of P22 gnd to P21, the LEDs are dimmed.
SW9 is on VDD and the power output is set to 3.3V
If SW8 is on and SW9 is put on either LIPO or USB, the LEDs go to full brightness.
When SW8 is off, switching to LIPO or USB will cut power.
Current with dimmed LED, VDD: 3.3V, SW8 OFF, SW9 VDD
Current with full brightness LED, VDD: 3.3V, SW8 ON, SW9 LIPO
Current with SW8 from off to on, VDD 3.3V, SW9 VDD
Funnily enough, when switching SW8 to on, the measurement becomes much more noisy, since most likely other ICs are now powered.
2.
When the PPK is used as a meter, with power coming from the Debug USB (not nRF USB) the current measurement does not make sense
Current, LED on/off, SW8 on, SW9 VDD
The phase with less noise is when the LED is off, the phase with more noise is when the LED is on
Additionally, every LED transition (hi to lo and lo to hi) causes the LED from the debugger IC to flicker.
So now to the specific questions:
Why does the weird behavior in 1. happen?
Why does the ppk in meter mode not measure the led current BUT does suddenly have more noise when the LED is on?
The average current in the LED low state in image is around 560 to 600µA but the average current in image 4 is 800µA, ... why?
Is there a chance that this behavior is due to a broken ppk oder dk (the "problems" described were there since the dk and ppk were fresh out of the box)?
Why does the debugger led flicker on transitions (any proper decoupling, which I assume is present, should mitigate that)?
Thank you for any help