LPC55S69 : read SecureGPIO state

EugeneHiihtaja — Mon, 06 Apr 2020 06:31:30 GMT

Hi !

Do I understand right :

1. If gpio pin configured as secure GPIO (via IOCON and SecMask ) it can't be used by GINTx peripheral ?

As result pin can't be used for wakeup MCU from PowerDown low power mode ?

Secure GPIOs can generate interrupts if they included to PINT peripheral only.

2. For protect reading state of pin it is enough to use SecMask only. IOCON setting is not mandatory ?

3. For protect writing to secure GPIO, IOCON and SecMask should be configured. Is this so ?

4. If pin configured for FLEXCOMM peripheral ( for example SPI SSEL), for protect reading of this kind of pin,

it is enough for configure SecMask only.

Please clarify those combinations.

Regards,

Eugene

Re: LPC55S69 : read SecureGPIO state

Omar_Anguiano — Wed, 08 Apr 2020 21:46:10 GMT

I will gladly answer your questions:

If GPIO is configured as secure, the GINT is not an option, I suggest to use Secure PINT, please refer to Chapter 20 in the User Manual.
The SecureMask allows us to control the on/off state of the normal GPIO read path, this is enough for only reading.
Yes, they must be configured. It is also important to add that two conditions must be met in order for a pin’s output bit to be driven onto the pin:

->The pin must be selected for secure GPIO operation via IOCON (FUNC value must be 10).

->The pin must be selected for output by a 1 in the DIR register.

If either or both of these conditions is (are) not met, writing to the pin has no effect.

4. Although the peripheral is configured as secure, it still can be acceded through the GPIO, so configuring the GPIO as secure is needed.

For more detailed information I suggest you check this application note: https://www.nxp.com/docs/en/application-note/AN12326.pdf

Let me know if this is helpful, if you have more questions do not hesitate to ask me.

Best regards,

Omar