Hover Free Hardware Diagram

JohnBuschert

Here is a hover free pin diagram with other useful hardware info on it. LFSaw was working on one back in August but it was the wrong orientation. I wanted one to post on my wall, so I made my own and here it is for anyone to use. I changed the color scheme for many of the pins because the scheme used in the IDE hover diagram is truly bizarre (ground is red!!??). LFSaw had a good idea to put other useful hardware info on the diagram which I have also done. It's hard to find some of this and I'm still unsure of a couple items so here are my questions:
1. The BBB specs say that the 5V supply has 250mA available. Bela info repeats that. But the Bela board draws some current for itself so there can't still be 250mA left. Does anyone know how much is realy available from the regulated 5V line on Bela to power user circuitry?
2. The "weak" 5V line has a resistor in series that is named as 100 ohms in one place and 220 ohms in another. I can see no value listed on the schematic.

Is there any other useful hardware information that should be included? I'd be glad to make further revisions.

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Remork

thanks, should prove useful!

JohnBuschert

I just looked more closely and found the value of the series resistor on the weak 5V line. It is 100 ohms. I'm still eager to know how much current is really available on the 5V regulated line from BBB.

giuliomoro

JohnBuschert I'm still eager to know how much current is really available on the 5V regulated line from BBB.

It's complicated. I used to think it was limited to 500mA, but actually the datasheet for the PMIC would seem to indicate that there's up to 2A on Vsys (which is what is broken out to P9.07). I therefore think that the original note " 250mA Max Current" on the original document was actually referring to the approx amount left after the on-board current usage was subtracted from the 500 mA that a USB 2.0 port is supposed to provide. OTOH, in the ~10 years since, most USB host ports have evolved to provide 2A or more without asking questions, so probably you can draw much more current there than 250mA. However, the note in the document that from P9_05 ( which is connected directly to the barrel jack) you can get "1A Max Current (only if DC jack powered)" makes me think that the limiting factor may not the PMIC, but rather the trace size of each 5V line. I expect you'll probably be fine with 1A on either (assuming your USB power provides enough current if you are USB-powered), but don't blame me if it smokes!

JohnBuschert

Thanks Giulio. I changed the label on that 5V supply to "Ext/USB" to better reflect the source and the current as "250mA or more depending on the source" as per your information. I've attached the latest version of the diagram in png format. I also corrected the D10 label. I can't seem to upload pdf to this forum, is there a trick to that?

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giuliomoro

JohnBuschert I can't seem to upload pdf to this forum, is there a trick to that?

unfortunately not

giuliomoro

+3.3V from BBB regulator max 250mA

I checked the schematics and that is the VDD_3V3B line, which is derived from SYS_5V via a dedicated TL5209 regulator. The regulator is 500mA max, but some current is needed on the BBB itself (not idea how much). The original document claimed it was 250mA, but it could be even more than that, again assuming that enough current is available on SYS_5V.

JohnBuschert

OK, there probably is not a simple hard maximum for these so I've changed the wording from "max 250mA" to "250mA available". I've updated the diagram at the top of this post also to reflect all these changes so if someone sees it and copies it without scrolling down they get the correct info.