Nucleo-G474RE: What is the intended use of JP7?

Forum|Forum|7 years ago
July 26, 2019
7 replies
1430 views

Nucleo-G474RE has JP7, which pulls down BOOT0 pin to ground when a jumper is installed, but this alone does not control boot options. What is the intended usage of JP7? Does it have something to do that Nucleo-G474RE comes with nSWBOOT0 option bit cleared?

STM32G4 series

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Uwe Bonnes

Chief

Well, the jumper allows to pull PB8-BOOT0 low. It give you options to play with.

Yoichi ShinodaAuthor

Senior

PB8-BOOT0 is active high when used as BOOT0; pulling it down doesn't have any effect in this case. For using PB8-BOOT0 as GPIO, why this particular pin is provisioned for pull down?

Mike_ST

ST Technical Moderator

Dear Yoichi,

Yes you are right, on this board, by default, the option bytes are set with nSWBOOT0=0 and nBOOT0=1.

Meaning that, in this case, pin BOOT0-PB8 is not used for BOOT configuration, and you can use PB8 as normal I/O.

You are free to set back nSWBOOT to 1 thanks to STM32CubeProgrammer and use PB8 for BOOT configuration.

In order to give better visibility on the answered topics, please click on 'Best answer' on the reply which solved your issue or answered your question.

Yoichi ShinodaAuthor

Senior

Yes. I understand the nSWBOOT option. My question is about "an intended usage of JP7".

Mike_ST

ST Technical Moderator

When nSWBOOT=1, and JP7 is fitted, it allows to pull-down BOOT0/PB8, and avoid having BOOT0 floating.

When nSWBOOT=0 and JP7 not fitted, you can use PB8 on CN5 or CN7.

In order to give better visibility on the answered topics, please click on 'Best answer' on the reply which solved your issue or answered your question.

Yoichi ShinodaAuthor

Senior

Yes. I understand the nSWBOOT option. My question is about "an intended usage of JP7".

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