STM32L0 Discovery + Ammeter

jon239955_stm1_st · ‎2015-10-17

Posted on October 17, 2015 at 12:19

I have an STM32L0 DISCOVERY board and I remove the jumper from JP4 and attach my own ammeter between pins 1 and 2.

The demonstration software shows between 210uA - 300uA repeatedly but does not execute code. The LEDs do not flash and the ePaper display does not update.

If I short pins 1 and 2 on JP4 with the provided jumper, all works OK. As this is simply connecting 3V3 to VDD, I do not understand why my ammeter is preventing the code from executing. I am using a Keysight U1232A set to uA scale (upto 600uA).

Has anybody seen a similar problem or know what might be causing this?

stm322399 · ‎2015-10-17

Posted on October 17, 2015 at 15:09

Try a higher caliber. When the application starts it might draw up to 10mA, and cause a fatal voltage drop at the ammeter, which resets the MCU, etc ...

Once the application has started and entered low power mode, change the caliber quickly. At this moment most ammeter will open the circuit, but it is likely that the MCU can live on decoupling capacitance if the circuit is closed again fast enough.

jon239955_stm1_st · ‎2015-11-11

Posted on November 11, 2015 at 22:19

Sorry for the delay in my response, I did not receive any notifications for this!

Yes, I switched the ammeter to a higher range and that allowed the board to start. Then I was able to switch over back to the smaller range and observe the (very) low current range instead.

So your answer was correct 🙂