Power Bare Onion Board?
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I'd like to feed power directly into the Onion board, rather than via the Dock or Mini-Dock. However, when I do (3.3V & GND on the appropriate pins) nothing happens. (The board is still OK: when I put it back on a Mini-Dock, it boots up and runs.)
I would look at the board schematics and figure it out myself, but those are not accessible (the wiki link to the schematic PDF at https://wiki.onion.io/create/Documentation/Hardware/Schematics/Omega.pdf says "Forbidden. This wiki is set to no-edit mode.")
Can anybody explain how to feed in power directly, or else get the schematics un-protected somehow?
Thanks!
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@Dave-M Glad you mentioned that went there the other day and the link didn't lead to what I thought it should. Forgot to post.
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After poking around through tags, I found the schematics at Github:
https://github.com/OnionIoT/Onion-Hardware
I suspect I need to pull the reset line up or down but not 100% sure yet. The schematic symbol for the reset switch suggests a NC switch pulled up to 3.3v, with a 1k/3k divider, and on the Omega, a 10k pulldown with a bypass cap. So without the Mini-Dock, it's a 10k pulldown, and with, it's a 1k pullup vs. a ~2.7k pulldown. None of that smells right, since reset is usually active low. I'm guessing there's some fancy chip-specific stuff going on with boot modes based on the state of RESET_L and GPIO11. Anybody know the real scoop?
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@Dave-M Whoops, sorry about the broken links in the wiki, they're fixed now and point to the PDFs in our Hardware GitHub repo.
The Reset pin needs to be held low, as mentioned in the wiki, the Reset is active-high.
The pinout diagram should be handy for your situation.
Are you providing power to the 3.3V VIN and holding both GND pins to ground? Are you also holding the other RST pin to ground?
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@Lazar-Demin: I was powering 3V3 and grounding both GND, but RST was floated. I'll try grounding it and see what happens. Thanks!
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I use the two upper right pins shown in the diagram: https://wiki.onion.io/Documentation/Hardware/Pinout-Diagram#omega-pinout-diagram. Works
% if the time!
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@Janus-Sanders: but also pull-down on RST, right?
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@Dave-M No. No pull down on RST is necessary. Just 3.3v on the correct terminals. This should only be done as a test and not soldered without the proper design.
I should mention, the Omega needs at least 100mah to run so make sure your power source has plenty of juice!
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@Janus-Sanders Huh, weird. I clipped on 3.3V with an ammeter (I was trying to see what the draw was). The board drew ~200mA and my 3.3V was solid (didn't dip) but the light never started blinking and the board didn't connect to WiFi. I guess I'll try again this weekend...
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@Dave-M yeah, strange. You're right about the 200mah's also. Does the Omega have surge protection? I've always switched power into the onion. Perhaps the direct battery to contact surge is getting in the way?
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I tried this yesterday with no success.
I supplied 3.3V to the Omega through an MCP-3302E which should have provided the correct 3.3v and up to 250 mA, which should be sufficient? Any issues with this?
There's some conflicting information in this thread, is there a definitive list of the minimum connections?
There are two RST pins, RSt and FW RST, do they both have to be connected to GND?
Do I have to connect both GND pins?
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I feel an explanation is in order. My Onion projects are designed to be portable and modular. I connect the Onion using the Adafruit LiPo Charger . This is the circuitry used to power the Onion with 3.3-volts, including connecting both grounds (from the charger) in the overall application. I wouldn't connect power directly without protection of some kind. I apologize if my comments were misleading. Also, the RST-GND (in a powered circuit) will reset or re-flash the Onion OS so a push button should be used for this feature and is not necessary for normal operation.
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@Janus-Sanders good idea, i must grab a bunch of those lipo chargers myself.
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@youlian-troyanov the link above was based on older designs. Consider Adafruit's PowerBoost products. (I'm not a salesman btw
)
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@Janus-Sanders cool, thanx
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@Janus-Sanders Looking at this again. The Powerboost boards seem to output 5V, but the Omega runs at 3.3V. What am I missing?
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@youlian-troyanov you're not missing anything. The confusion is in the specifics of my design. I using the Omega mini dock and powering the unit through it's mini USB port (5 vdc) eliminating a lot of custom wiring, cabling or converters :slight_smile:
