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Loading Flash on STM32F767 MCU with St-Link v2

hashtala
Associate II

Hello

newbie question

As I know I have to implement pull-up and pull-down on SWDIO/SWDCLK pins and also enter the boot mode by pulling down/up the BOOT0 and BOOT1 pins.

However I cannot exactly find all this information on datasheet and I am afraid I'm going to miss something. I learned about these in random youtube videos and googling. Could you please correct me if I am missing something? As far as I know I have to pull Boot0 down and use SWDIO and SWCLK pins. And after uploading the program just reset the MCU.

5 REPLIES 5
TDK
Guru

You dont need any pullup/down on SWD pins. Yes you need to pull down BOOT0. After uploading, most IDEs will run the program automatically. The Stlink interface needs SWDIO+SWCLK+NRST plus power at a minimum.

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hashtala
Associate II

Thank you for guiding me all this, really appreciate your patience and responses. I use Keil, which I believe does not restart the board (I flash it using USB) However, I am a bit confused about minimum power thing. and also, as I understood, if I use RST+SWDIO+SWCLK chances are IDE will restart the MCU right ? I could not find the RST pin on MCU though, is that terrible idea to just turn off Vdd and then turn it on back again to restart it ?

TDK
Guru

> I could not find the RST pin on MCU though

It's labeled NRST. The N means active low, so the chip is in reset when NRST is low.

> is that terrible idea to just turn off Vdd and then turn it on back again to restart it ?

Power cycling to run your code is perfectly valid. Not having NRST hooked up can work, but it can cause issues since it's not the default configuration if you don't know how to configure it.

Not sure about Keil specific questions. I have only used it briefly.

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Some of the STM32 need to be power cycled if the part was originally blank, as it will keep starting from ROM rather than run new code in FLASH

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I will try to go without NRST. Will post feedback