Having the same issue here. Seems to be something to do with either the bluetooth on this chip or the usb3 speeds drawing too much power. I tried to limit it to usb2 speeds but no dice. :’)
Would be lovely to have all the antennas working. :’)
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I was thinking this with mine but it’s the same here and doesn’t seem to go in any further. We could be wrong and it just requires a touch more force though?
What do you have RPITX going to? I count 8 cables exiting the top?
RPITX is just linked out for nothing now. The extra cable comes from a surface-mount antenna.
Just to confirm, I’m seeing the same set of symptoms: AC1200 dongle works on external USB-C on the AIOv2; doesn’t stay up on internal USB-C; nothing else connected to the internal header; nothing else on the AIO enabled except internal USB; tried removing the USB3 FPC to drop to USB2 speeds with no difference; dmesg shows the device cycling between connecting and disconnecting with the only errors being bluetooth opcodes etc. that don’t seem to be fatal (and none re. iwl/wifi); no issues with drivers, firmware etc.
@Greg_Dyke @Ch1enC Just double-checking the schematic; I found that the current-limiting resistor is 10K, which limits the current to 0.68A for the internal USB devices. A quick fix was to change the resistor below to 4.3 kΩ.
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Thanks, I don’t have a ready supply of SMD resistors in my boxes. I can see if I can wire up a TH resistor as a test tonight though. I assume just removing and bridging the current limiting resistor is a bad idea…
I assume just removing and bridging the current limiting resistor is a bad idea
Never do that! If you can’t find a proper resistor, you can swap it with the resistor below. That’s a 4.3k resistor, which limits the current of the side USB-C.
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You’re sure you mean 10k and 4.3k respectively? My napkin math would have expected at most ~100 ohms…
Thank you for your efforts! Is it a 0402 SMD resistor? I will get some to replace it.
Yes, it’s a 0402 SMD resistor.
Yes, the current limit threshold was caculate by this formule: I(current threshold)= 6.8k/Rset.
4.7kohm sufficient, or is it vital it’s closer to 4.3k?
Wait, so the WiFi card you sold us won’t work without doing that?
Might as well give it a go. If it’s a hardware fault we’re due replacements anyway.
What this is starting to look like is that the power budget was validated against a Wi-Fi-only device, and the dual-function MT7921AUN (Wi-Fi + Bluetooth) was either swapped in very late or not fully validated under simultaneous operation.
A few things line up too neatly to ignore:
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The MT7921AUN is a USB combo device; Bluetooth initialisation causes short but real current spikes.
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With the current Rset value (~6.8k), the USB rail is effectively capped at ~1A.
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Wi-Fi alone stays stable.
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The moment Bluetooth is enabled, the device browns out and the USB controller resets.
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Reducing Rset (or adding proper buffering) resolves the issue.
On top of that, the antenna mount PCB has extra connections beyond what was originally advertised, which strongly suggests the design pivoted late to support a combo card rather than a Wi-Fi-only module.
So to be clear:
This doesn’t look like a Linux driver problem, and it doesn’t look like a faulty MT7921AUN. It looks like the final hardware configuration cannot reliably power the card in its advertised dual-function mode.
If the expectation is that users must:
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rework a 0402 resistor, or
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accept Bluetooth being unusable,
then that needs to be stated plainly — because as shipped, the kit is sold as supporting Wi-Fi and Bluetooth, but only one of those works reliably without modification.
Happy to test further, but at this point the evidence points squarely at USB power delivery being under-spec’d for the chosen card, likely due to a late hardware change.
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Anyone able to recommend a Lipo to fit in the standard Uconsole cover with the correct plug?
I’m getting the described behavior too. Given this situation makes the power budget suspect, I’d like to focus on what size resistor can mitigate the situation without demanding rework by vileer. Whats the recommened bew resistor size, and where to obtain? Thanks.
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You can see in the table above the rough value to aim for (it doesn’t need to be precise) - I’d suggest anything between 6k (just over 1A) and 4k (around 1.7A), either of which is well above the USB3 spec for non-charger current draw with enough headroom for spikes and droops. And as also noted above, they’re 0402 size.