Fix for UAEFI sometimes not starting without USB connecteed

Hardware inside and outside of the ECU
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gurov
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Fix for UAEFI sometimes not starting without USB connecteed

Post by gurov »

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from discussion on discord:


5vp does not light up with just 12v below a certain battery voltage, causing a no-start condition

this was traced down to a severe enough drop at the main 5v regulator that would cause the main MCU to power down, aborting enabling 5vp, entering a loop.

fix is rather crude, but it's to force 5vp to initialize forcefully, MCU or not.

10k resistor between pin 7 and 5v rail, like in the picture.
1994 6speed supra turbo [ single turbo/1000cc ID/twin fuel pumps/bc2 262 cams ]. J&S safeguard for knock , UAEFI / 407 disco with rusefi / AEM EMS v2 / MS3pro PNP / Speeduino (mega2560 / teensy41 / stm32f411)
2020 BMW X3m - bootmod3 stage1
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AndreyB
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Re: Fix for UAEFI sometimes not starting without USB connecteed

Post by AndreyB »

gurov wrote:
Thu Apr 11, 2024 10:30 pm
this was traced down to a severe enough drop at the main 5v regulator that would cause the main MCU to power down, aborting enabling 5vp, entering a loop.
We still do not know real root cause right?

Similar looking boards one would work another would not, right? https://github.com/rusefi/uaefi/issues/59
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gurov
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Re: Fix for UAEFI sometimes not starting without USB connecteed

Post by gurov »

correct, still don't know the actual root cause, just breadcrumbs of symptoms with comparison to good board
1994 6speed supra turbo [ single turbo/1000cc ID/twin fuel pumps/bc2 262 cams ]. J&S safeguard for knock , UAEFI / 407 disco with rusefi / AEM EMS v2 / MS3pro PNP / Speeduino (mega2560 / teensy41 / stm32f411)
2020 BMW X3m - bootmod3 stage1
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