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LTDC pins slew rate in device tree [Zephyr]

xavierpacheco-eaton
Associate II

While looking at the stm32h745xihx-pinctrl.dtsi file I see the slew rate is defined for the QUADSPI pins, but the LTDC pins. Is it set to Very High speed implicitly? I would be concerned if they are set to Low Speed by default.

 

xavierpachecoeaton_0-1722444596119.png

Thanks in advance for any input.

1 ACCEPTED SOLUTION

Accepted Solutions
Sarra.S
ST Employee

Hello @xavierpacheco-eaton

According to the STM32H745 datasheet, in the LTDC paragraph, the output speed is OSPEEDRy[1:0] = 11which corresponds to very-high-speed configuration, and the high LTDC clock output frequency (up to 150 MHz), so, the slew rate needs to be set appropriately explicitly to handle these high-speed signals and to avoid concerns about the default configuration potentially being set to a lower speed. 

 

/omit-if-no-ref/ ltdc_de_pk7: ltdc_de_pk7 {
    pinmux = <STM32_PINMUX('K', 7, AF14)>;
    slew-rate = "very-high-speed";  // Explicitly setting the slew rate
};

 

 Hope that answers your question! 

To give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.

View solution in original post

1 REPLY 1
Sarra.S
ST Employee

Hello @xavierpacheco-eaton

According to the STM32H745 datasheet, in the LTDC paragraph, the output speed is OSPEEDRy[1:0] = 11which corresponds to very-high-speed configuration, and the high LTDC clock output frequency (up to 150 MHz), so, the slew rate needs to be set appropriately explicitly to handle these high-speed signals and to avoid concerns about the default configuration potentially being set to a lower speed. 

 

/omit-if-no-ref/ ltdc_de_pk7: ltdc_de_pk7 {
    pinmux = <STM32_PINMUX('K', 7, AF14)>;
    slew-rate = "very-high-speed";  // Explicitly setting the slew rate
};

 

 Hope that answers your question! 

To give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.