AM3356: HOW to output a HIGH-Z signal on AM335x Sitara?

Martin Roth

Prodigy 100 points

Part Number: AM3356

I need to output HIGH-Z signals for gpio57.

Assuming that gpio57 controls the output signal, would the following code output HI-Z (on Sitara AM3356 processor) ?

I assume that there is no PU/PD .

gpio_direction_output(57, 0);
gpio_direction_input(57);

Martin Roth

Motorola Solutions

over 2 years ago

+1 Bin Liu over 2 years ago

TI__Guru**** 169681 points

Hi Martin,

I personally didn't use these gpiod_* API in any kernel driver, but reading the kernel GPIO drivers, you only need gpio_direction_input() to not drive the GPIO pin. Setting the pin to 0 first is unnecessary.

+1 Martin Roth over 2 years ago in reply to Bin Liu

Prodigy 100 points

Thanks for the answer.

One more question.

After reset the all pins of AM335x Sitara are set as GPIO input (mode 7). Does it mean that it is HIGH-Z by default after reset?

Thanks again for the answer.

+1 Bin Liu over 2 years ago in reply to Martin Roth

TI__Guru**** 169681 points

Hi Martin,

After reset, all GPIO pins are in input mode by default, output is disabled, so yes, the pins by default is HIGH-Z.

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AM3356: HOW to output a HIGH-Z signal on AM335x Sitara?