Pine A64 Plus Fails to Boot

[MarkHaysHarris777]

Hey Mark, thanks for your help the other night!  You got me unstuck when I was pulling my hair out - much appreciated.

I'm not sure blaming the power supplies is the right answer here.  I'm measuring roughly 0.3A drawn - it's not taxing any of these power supplies, nor the connector.  A quick google says brand-name Micro USB connectors are rated for 1.8A for VCC and GND, and even the crap chinese ones must be good for half that.

I don't think ripple is a problem either - or it'd be causing crashes much more often than just at boot.  My board has run 24 hours without a crash (until I shut it down), once it made it through booting.

So, my working theory is that at some point in the boot, a bunch of hardware is switched on at once, causing a short/sharp sag in the voltage.  (Why it doesn't cause a problem with an HDMI monitor, I don't know, timing issue?)  That's the sort of thing I've seen fixed with a decoupling capacitor, storing a wee bit of energy locally, rather than in the power supply filter caps at the far end of that - probably thin - wire.

Your PI filter undoubtedly works, but I'm not sure it's necessary.  A single capacitor on a connector on the Euler bus is smaller and easier to add than circumventing the entire power input connector and filters.  I think I'll try the biggest ceramic I can find first and see what happens.  Might also see if I can get the o'scope to capture a voltage drop.  But... tomorrow.

hi again,  you're welcome !  ... my pleasure.

... on the connector,  its not a theory;  the engineers at the plant have confirmed that the microUSB connector does not work properly, and they have decided to replace the microUSB with a barrel connector;  the new sopine base boards are now shipping with the new barrel connectors; at some point the pine boards will get this same revision.

marcus