Power profile gone crazy after firmware update

[AletheaIT]

I've been using the power profiler 2 kit for a couple of years and everything has been working fine - a few days ago I was promoted to do a firmware and version update (which I did) and suddenly everything is broken

the power profiler is now putting out 4.79v in ampere meter mode with no external power attached and in source mode, it is outputting 2.335v with the enable power output disabled. Setting 800mv output and enabling this raises the output to 2.897v out and the current measurements are now completely random with no correlation to load

is there a way to roll back to older firmware on this and undo the updates that have broken the device?

[SwRa]

Hi Alethea,

Could you try the following steps and see if the ppk2 works fine.?

Disconnect all other nordic devices from the computer, turn off the kit and remove it from the plastic by removing the four screws. Insert USB to J2 (USB DATA/POWER). Short a connection between GND (e.g on the four pin power output header) to TP34 on the PPK2. While holding the jumper cable, turn the kit on and remove the jumper. Now the PPK2 should be in bootloader again.

Open the PPK app, and select the device which is now just a serial number.

When selecting it, the user will be prompted to program the application and it should now be working again.

Best Regards,

Swathy

[AletheaIT]

thanks for that - I did the reset as you suggested and it reloaded 

but it still seems to have the same strange behaviour

when I first connect it to the mac or PC (I have tried two different computers and fresh installs) in source meter mode, with the supply voltage at the minimum (800mv) and the enable power output toggle set to OFF, there is 2.3v coming out of the vout pin, I can even light an LED with this 

if i leave the enable power in the off position and raise the voltage in the software to max (5000mv) , we see 4.68V at the Vout pin even though the power output is switched off 

If i switch the Enable Power supply to on, this rises above the 5V to 5.48V!

If I set a source meter mode output of 3300mV we get out 3.207V when the out put is set to off or 3.932 when it is turned on

testing this with a single 100Ohm resistor it shows a current draw of 17.43mA when Enable power is off and 18.89ma when on 

so it seems the on / off has gone wrong and after the update, it is no longer able to turn off when in source meter mode

and also, it seems perhaps the internal switching has malfunctioned as this is showing a significant difference in current regardless of which number we use

3.207v / 100Ω should show 32.07ma or 3.932v should show 39.32ma vs 17.43mA and 18.89ma respectively - there was always a compensating voltage drop but never this sever - this indicates the ppk has an internal resistance of 100.8 Ω. when measuring 30ma which seems a lot higher than before the update


Any ideas - can I roll back to the previous versions to test ? 

[AletheaIT]

Thanks for the troubleshooting steps - unfortunately the reset didn't resolve anything. I've done some systematic testing with a calibrated 390.11Ω resistor to better understand what's broken.

Test 1 - Ampere Meter Mode (External Power):

• External 4.1V supply connected (as I've been doing successfully for the past year)
• PPK2 shows 4.1V output initially ✓
• Added 390Ω calibrated resistor load
• PPK2 current reading: 6.7mA
• Voltage measured directly across resistor: 2.628V
• Issue: 1.51V drop in the PPK2 circuit (equivalent to ~225Ω internal resistance)

Test 2 - Source Mode at 3.3V:

• No load: 3.93V output
• With 390Ω resistor: voltage drops to 2.37V, current reads 6.11mA
• Issue: 1.56V drop for only 6mA of current = ~255Ω internal resistance

Test 3 - Source Mode Power ON/OFF comparison:

• Current readings are reasonably accurate when "Enable Power" is ON
• With "Enable Power" OFF: current readings are almost double the actual values

Test 4 - Lower Current Test (500µA range):

• Used 6.84kΩ resistor in source mode at 3.3V
• Voltage drops from 3.93V to 3.651V, current reads 500µA
• Issue: 0.282V drop for 500µA = ~564Ω internal resistance (it seems to get worse at lower currents)

The PPK2 is now behaving like it has a massive series resistance (200-255Ω) when it should be dropping maybe a few millivolts at most. Before the firmware update, this was all working fine but now I can power a LED with the output turned OFF and the readings don't make any sense

would it be possible to get a clean or earlier version of the firmware to try - perhaps something went wrong during the update but it seems stuck using a massive load and sadly is not really usable as is.