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Pin values when RESET is pressed.

JAlca
Senior

Hi all,

I'm working with a STM32F303CCT6, and I'm testing the different pin values when Reset is pressed. The Reference Manual says the reset value for GPIO_MODER is 0, so all GPIO are inputs.

But I'm testing my MCU (first I erased all memory) and have a HIGH value on A15 with or without RESET pressed...

Its this ok?

3 REPLIES 3
Danish1
Lead II

When there's no code in FLASH or you select the appropriate BOOT setting, the stm32 will start up running the ST-supplied bootloader.

This bootloader will use certain pins to allow you to download your firmware e.g. over a UART or I2C. See the data sheet for details.

Also coming out of reset, any debug pins (JTAG or SWD) will be enabled and pulled appropriately.

Hope this helps,

Danish

> The Reference Manual says the reset value for GPIO_MODER is 0, so all GPIO are inputs.

No, it doesn't say so.

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JW

Youre right!

I misunderstood, thanks. 🙂