STM32MP15x default pins

[gil_he]

hello,

I understand, on power-up, there are default pins for UART4/5/7/8, for SDMMC2, etc.

Each port can have one specific AF, correct?

Because it defines the roles of all the port pins.

Question 1:

UART4 has a default pin for TX on PG11 (AF6) and for RX on PB2 (AF8).

SDMMC2 has a default pin for D0 on PB14 (AF9), for CMD on PG6 (AF10) and for CK on PE3 (AF9).

So, port G has AF6 for UART4 (TX) and AF10 for SDMMC2 (CMD). For default.

Is that possible because we are talking on two different boot modes?

Otherwise, two different AFx cannot be defined for the same port, correct?

Or, if this is valid (two different AF for the same port), should I be using a different UART, since port G cannot take AF6 (for UART4) and AF10 (SDMMC2) in the same setup?

Question 2:

In, https://wiki.st.com/stm32mpu/wiki/STM32_MPU_ROM_code_overview#Boot_mode_selection, section 3.2.2 UART Boot, the GPIO pin and AF table:

UART5 requires AF12 for PB5 (RX) and AF14 for PB13 (TX). different AF for port B.

Is that valid?

 

thank you

Gil

 

[Neeraj Dantu]

Gil,

The alternate functions are for each pin and unrelated to each other in any port. You can set any alternate function on any pin as long as it makes sense in the peripheral defined. You do not need to set all pins of a port to a particular alternate function.

As far as booting interface goes, you can modify the default pins ROM code uses only for SD, eMMC and QSPI. You cannot change the default pins for UART interface, but you can select a different UART interface from which you can boot, unless disabled specifically in OTP.

Hope that clears things up.

Best,

Neeraj

[Author]

Posts