I’ve looked for a simple answer to this question but can’t find one specific enough for what I want to figure out.
Basically, if I want to run the BBB using a socket interface over ethernet and do not want any HDMI or UART or I2C, etc, but do want the on-board flash, what is the largest number of GPIO pins that could be made available (I do want the analog pins as well)?
Is it really just the Mode7 list in the system manual, or are some always used for some other purpose or otherwise not available?
Any help appreciated!
Yes, I looked at both. But, I’ve learned from experience that what is written is sometimes not what is reality. I was wondering if anyone had already gone through the exercise of maximizing the GPIO pins.
Well, i wrote it. I designed the board. Feel free to take the schematic and a pin and mark them off yourself.
I stand corrected! There are a maximum 69 GPIO pins available. Or maybe less than that. Depends on what features on the board you plan to keep and how many you plan to disable, like HDMI and eMMC which eat up a about 30 of them. There are all listed in the System Reference Manual. All GPIO pins are accessible under Mode 7.
Ok, thanks for the help!
I’m a total newbie with BBB, don’t even have one yet actually, but if I disable eMMC and run from a microSD card, can I get the 69 GPIO pins? I want to know the max before I propose using one for a project.
You will need to disable the HDMI as well. There are tables in the SRM that show the pins that are used by the expansion headers and on the board.
Thanks for the link! I’ll take a look.
Remember you can always add GPIO expanders.
This wiki page (http://circuitco.com/support/index.php?title=Cape_Expansion_Headers) has all the information that you would need regarding the GPIO pins.