Kinetis Microcontrollers中的主题 GPIO Direction vs Output_Enable

GPIO Direction vs Output_Enable

deniscollis — Fri, 17 Jan 2020 19:27:57 GMT

I just need some clarity here. I am porting some code to a K8x from an ARM MCU from another manufacturer. They have a GPIO Data Output Enable Register. There is no concept of 'direction', as the GPIO Data Input Register always reflects the state of the pins, whether output is enabled or not.

Does the Kinetis GPIO Data Direction Register work in the same way? That is, does the Kinetis GPIO Data Input Register reliably reflect the state of the pin, without regard to the GPIO Data Direction Register setting?

Background: The pin connects to an open drain bus control rail. Output register is normally high. Reading input register indicates that another device has grabbed the bus.

Thanx,

Denis

Re: GPIO Direction vs Output_Enable

Robin_Shen — Sun, 19 Jan 2020 03:20:40 GMT

Hi Denis,

The Kinetis GPIO Data Input Register reliably reflect the state of the pin, without regard to the GPIO Data Direction Register setting.

Here you can see the test result of example gpio_led_output:

This example toggle led(GPIOC pin 8 configured as as output), we are able to see the GPIOC_PDIR[8] toggle during debug.

Best Regards,

Robin

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