Vbat pin drawn high currebt when power is off

SJati.1 · ‎2021-12-15

I am using Nucleo 144 H745ZQi , connected vbat pin directly using coin cell, when power is off/unconnected, LD7 led ovcr indicator turned on and current consumption drawn from baterry was 50mA, also the LD5 led turned on. However when i reconnect the power, either using option jumper on stlink or ext 5V then the LD7 turn off and it seems normal again. I wonder why? Please help me, because it's will waste the battery when used power off.

waclawek.jan · ‎2021-12-16

Again, check if LSE pins are connected to the crystal, and if they are disconnected from anything else on the board.

JW

SJati.1 · ‎2021-12-16

From the schematic on Nucleo , X3 crystal need Capactor on C78 an C77, and no caps on board, does it mean I need to add capacitor on board? or is this necessary

waclawek.jan · ‎2021-12-16

> X3 crystal need Capactor on C78 an C77, and no caps on board

X3 does not necessarily need a capacitor. Read AN2867.

Try to experiment with RCC_BDCR.LSEDRV (note that LSEON has to be 0 for this to be possible).

Nonetheless, if you are sure the SB connecting PC14 and PC15 to the "Morpho" connector are disconnected, and LSE still does not start, even if you've checked in debugger that LSEON is set, then you can experiment by adding some few-pF capacitors there.

@Peter BENSCH , don't you incidentally have this board at hand, to try?

JW

SJati.1 · ‎2021-12-16

I try for high drive and another option it still doesnt work. I've check the solder bridges they are disconnected from morpho connector. LSEON bit is set but LSE never be in ready. Are there any software solution first to try before I start adding hardware?

Peter BENSCH · ‎2021-12-16

@Community member Unfortunately, I don't have the NUCLEO-H745ZI-Q at hand at the moment, but I'm happy to test it as soon as it's on my table.

@SJati.1 There are sample projects for all NUCLEO and DISCOVERY boards in the repository, either in your local repository or in Github, e.g. the example RTC_Alarm. Please note that the examples in the repository refer to the libraries there. If you only clone/use the example directory, you have to adapt the paths.

Regards

/Peter

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