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Author Topic: GPIO electrical specs  (Read 1665 times)

oskaratk

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GPIO electrical specs
« on: April 23, 2014, 06:59:18 AM »
Howdy,

I am scanning the manuals - but cannot find info whether the GPIO pins need external pullup/pulldown resistors. What is the max current per port ?

I need to drive the inputs of an VNQ5156 - typical 10 uA, I guess that should not be a issue.

Thanks
Oskar

MBR

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Re: GPIO electrical specs
« Reply #1 on: April 23, 2014, 09:07:15 PM »
The green GPIO LED draws at least 1mA and I have sucessfully tried custom LEDs which draws up to 3 mA. By the FEX Guide on SUNXI Wiki is minimal selectable port drive capacity 10mA (see http://linux-sunxi.org/Fex_Guide#Port_Definitions). So, IMHO, microampers are really not an isue.

dave-at-axon

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Re: GPIO electrical specs
« Reply #2 on: April 24, 2014, 06:21:39 AM »
Hi Oskar,

The basic datasheet shows the buffer strength as 20mA so you will be okay with your drive.

As for the pullups, each GPIO can be configured for this but that is only after booting. The datasheet shows these default to input and can cause driver inputs connected to them to float high, so if you need to make sure that your output is off, use an external pullup/down resistor to keep the driver in the known state that you want it to be until the software is ready to run.