GPIO pin max voltage

adhdengineer · August 19, 2013, 06:23:12 PM

I've recently got myself an A13 OLinuXino board (the non-wifi one) and i'v got it up and running with my own debian install, but now i'd like to start playing with the GPIO pins. Actually the CSI pins to be precise.
I'm writing my own driver for educational purposes and I want to hook up an arduino to the pins to provide a fake image source, but i don't want to break anything by putting 5v on the pins if they're only rated 3v3 etc. I made that mistake when i accidentally put 12v down my PCs 5v USB power rail and blew the soundcard chip on the motherboard.

For those interested i've got the driver in a state where i can read and write the CSI registers via ioctls and i've discovered that if the input format is set to RAW then if i set the output format to 1111 it hangs the system and needs rebooting.

anra · August 19, 2013, 10:12:51 PM

I am not sure about the maximum voltage. But I did some test taking the 5V and a push button. My goal was to detect my button when it was pushed and all worked correctly. Maybe using 5V continuously could be not good...I don't known Maybe someone here has a better answer

JohnS · August 20, 2013, 12:12:20 AM

Unless you have evidence otherwise, 3V is about the safe max. Anything higher and you're gambling.

Chips normally have detailed datasheets where limits are specified. The Allwinner datasheets are very poor in some respects but have you at least checked what they do say? They're all on the net.

John

adhdengineer · August 20, 2013, 01:07:52 AM

Quote from: JohnS on August 20, 2013, 12:12:20 AM
Unless you have evidence otherwise, 3V is about the safe max. Anything higher and you're gambling.

Chips normally have detailed datasheets where limits are specified. The Allwinner datasheets are very poor in some respects but have you at least checked what they do say? They're all on the net.

John

It's a fair point and well made. 3v typical and 3v3 max. I'll make a little breadboard arduino running at 3v to drive the test

Lurch · August 20, 2013, 11:12:45 AM

Depending on where you are, you might be able to get one of these boards:
http://www.watterott.com/de/8-channel-Bi-directional-Level-Converter-TXB0108

JohnS · August 20, 2013, 12:15:32 PM

Sparkfun and others also sell level convertors.

John

miga · January 17, 2014, 03:50:09 PM

I tried to find an answer to the very same question for all OLinuxinos after burning my RasPi serial console (UART) pins with 5V from USB. (Luckily other pins still seem to work.)

I thought the greatest advantage of AtMega/Arduino is tolerance to voltage levels between 1.8V-5V.

Did anyone find specs for OLinuxino?

JohnS · January 17, 2014, 04:55:52 PM

Try the datasheets? You can be fairly sure it's about 3V. Don't try 5V unless you don't care when your board dies.

If you want a 5V-tolerant CPU there are lots but I believe not Allwinner chips.

John

miga · January 17, 2014, 05:08:06 PM

I just burned my RasPi's UART ports (likely they were secured, so BCM chip still lives), but I am still curious whether there is Linux-hosting chip that is tolerant to 5V? E.g. really children-friendly?

JohnS · January 17, 2014, 10:23:06 PM

I don't see why you insist on 5V. Almost anything can be 3V and there are level converters etc for other voltages whether 5V, 12V or indeed mains electricity (here, 250V AC).

John