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pico W run and 3v3-en pins

Pi Pico W: what is the practical difference between RUN and 3V3_EN pins?

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Asked yesterday

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Pi Pico W datasheet states:

3V3_EN connects to the on-board SMPS enable pin, and is pulled high (to VSYS) via a 100kΩ resistor. To disable the 3.3V (which also de-powers the RP2040), short this pin low.

and

RUN is the RP2040 enable pin, and has an internal (on-chip) pull-up resistor to 3.3V of about ~50kΩ. To reset RP2040, short this pin low.

Which means that RUN resets the microcontroller and 3V3_EN powers it off. Practically (in application) both sound to me as they will only reset the microcontroller. I tried also using both pins and haven’t noticed any difference in the behavior: microcontroller starts over, once the pin is released (i.e. pulled up again).

So, the question is, what is the practical difference between using RUN pin or 3V3_EN in applications?

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asked yesterday

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Vadim

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  • Rpi Pico W Datasheet – rpi datasheets.raspberrypi.com/picow/pico-w-datasheet.pdf 2.1. Pico W pinout 3V3_EN connects to the on-board SMPS enable pin, and is pulled high (to VSYS) via a 100kΩ resistor. To disable the 3.3V (which also de-powers the RP2040), short this pin low. RUN is the RP2040 enable pin, and has an internal (on-chip) pull-up resistor to 3.3V of about ~50kΩ. To reset RP2040, short this pin low. – tlfong01 yesterday  
  • (1) 3V3_EN is to enable the on-board SMPS. I always leave it High. (2) RUN is to reset the RP2040. I also always leave it High, except from time to time, when I want to reset Pico., – tlfong01 yesterday   
  • 1(3) So, if you like, 3V3_EN is hardware power off/on resetRUN is software reset. – tlfong01 yesterday  
  • 1What will be the practical difference between software and hardware reset for Pi Pico then? – Vadim 23 hours ago
  • References to POR (Power-on Reset): (1) Power-on reset – Wikipedia en.wikipedia.org/wiki/Power-on_reset (2) Power-on Rreset and related supervisory functions – MaximIntegrated maximintegrated.com/en/design/technical-documents/app-notes/3/… – tlfong01 5 hours ago  
  • MicroPython Reset Functions docs.micropython.org/en/latest/library/machine.html (1) machine.reset() Resets the device in a manner similar to pushing the external RESET button. (2) machine.soft_reset() Performs a soft reset of the interpreter, deleting all Python objects and resetting the Python heap. (3) machine.reset_cause() Get the reset cause. See constants for the possible return values. (4) machine.bootloader([value]) Reset the device and enter its bootloader, typically used to put the device into a state where it can be programmed with new firmware. – tlfong01 4 hours ago  
  • Rpi PicoW 3V3 En Schematicimgur.com/a/gBluUTJ – tlfong01 42 mins ago   

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