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Author Topic: GPIO logic level?  (Read 1072 times)

thom_nic

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GPIO logic level?
« on: April 07, 2017, 09:23:45 PM »
Let's say I have a GPIO input that I want to drive high - is it 1.8v or 3.3?  Assume it is 3.3v correct, I haven't found it explicitly stated anywhere.
« Last Edit: April 10, 2017, 09:18:47 PM by thom_nic »

JohnS

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Re: GPIO logic level?
« Reply #1 on: April 08, 2017, 01:22:01 AM »
It'll be in the TI doc.

http://processors.wiki.ti.com/index.php/Sitara_AM335x_Portal

Or web search on something obvious like
am335x datasheet

John

Chester Gillon

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Re: GPIO logic level?
« Reply #2 on: April 08, 2017, 03:33:19 PM »
Looking at the the AM3352 SOM Rev C schematic all six of the AM3352 VDDSHV1 to VDDSHV6 "Supply voltage range for the dual-voltage IO domain" are connected to 3.3V.


This means all GPIOs use 3.3V signaling.

thom_nic

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Re: GPIO logic level?
« Reply #3 on: April 10, 2017, 05:17:01 PM »
Thanks Chester. 

Funny enough, I *did* have the mental capacity to google the datasheet!  I'll admit I did not read every word of it but from what I can tell, the TI datasheet actually *does not* specify an absolute voltage but a range relative to the supply cell voltage (suggesting it could be *either* 3v3 or 1.8v depending on configuration.) Unfortunately neither the Olimex user guide nor the GPIO pinout doc (https://www.olimex.com/Products/SOM/AM3352/AM3352-SOM/resources/AM3352_SOM_GPIOs.pdf) actually call out the exact value.  But by finding those signals on the SOM schematic I believe you are correct.  Thanks again!