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A.R.C
A.R.C
Associate
March 4, 2019
Question

STM32L4 Pin State in shutdown mode

  • March 4, 2019
  • 2 replies
  • 1013 views

We are trying to set the STM32L431 controller to shutdown mode.

During the shutdown mode, Pin PA15 shall be at low level.

Unfortunately the pin does not stay at low level during shutdown.

We have configured the pin with „HAL_PWREx_EnableGPIOPullDown(PWR_GPIO_A, PWR_GPIO_BIT_15);“

Because PA15 is a JTAG pin and equipped with internal pull-ups during reset i am searching the problem there.

Do I use the wrong pin configuration or is it not possible to achive a low level on PA15 in shutdown?

Thank you

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2 replies

turboscrew
turboscrew
Senior III
March 5, 2019

RM0351 says:

"I/O states in Shutdown mode

In the Shutdown mode, the I/Os can be configured either with a pull-up (refer to

PWR_PUCRx registers (x=A,B,C,D,E,F,G,H), or with a pull-down (refer to PWR_PDCRx

registers (x=A,B,C,D,E,F,G,H)), or can be kept in analog state. However this configuration is

lost when exiting the Shutdown mode due to the power-on reset.

The RTC outputs on PC13 are functional in Shutdown mode. PC14 and PC15 used for LSE

are also functional. 5 wakeup pins (WKUPx, x=1,2...5) and the 3 RTC tampers are available."

I guess the ports are in high Z state, but the pull-ups/downs are there.

A.R.C
A.R.CAuthor
Associate
March 5, 2019

Yes I have seein this section in the manual.

I just found out why it was not working on my controller. During debugging all pins assigned to JTAG behave a bit different. If I startup the system without debug connection, everything is working fine.

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