RFLink and boot from USB

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manjh
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RFLink and boot from USB

#1 Post by manjh » 08 Jun 2021, 11:36

I have been using RFLink for a number of years now, without a glitch. It is USB attached to my Raspberry Pi 4.
But I am making changes: in stead of booting from the SD card, my Pi now runs off a USB attached SSD. Because the controller chip in the SATA/USB cable does not properly support UASP, I am running it off USB2 for now (awaiting a new cable with the correct chip, so I can connect to USB3).

This brings me to my question. Sometimes (not always) the Pi refuses to boot. I noticed that this does not happen when I disconnect the RFLink.
After booting with no RFLink attached, I can connect the RFLink cable again and everything is working.
Does this make any sense?

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Ath
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Re: RFLink and boot from USB

#2 Post by Ath » 08 Jun 2021, 13:02

Sounds like a power issue, can possibly be resolved by using a larger-spec powersupply, or by powering, f.e., the ssd or rflink using an extra power supply.
/Ton

manjh
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Re: RFLink and boot from USB

#3 Post by manjh » 08 Jun 2021, 14:30

I use a "real" Raspberry 3A power supply. Rflink is on a separate supply, so there should be enough juice to go around...

manjh
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Joined: 08 Feb 2016, 11:22

Re: RFLink and boot from USB

#4 Post by manjh » 08 Jun 2021, 15:46

OK, I think I may have found a workaround.
Just to get to the bottom of this, I pulled the Pi and the RFLink from it's place, and attached it to a HDMI monitor in my office, so I can now at least see what is happening during boot.
When booting with RFLink attached, I get a number of errors about resetting the USB power state, or something like that.
Just for the heck of it, I pulled the dedicated 5V power supply from the RFLink, and let it get power from the Pi through USB.
This removed all errors.... it now boots perfectly!

So the solution is not to add more power, but rather to remove it... less-is-more...

So, although this removes my problem, I still don't really understand. But hey, such is life... :D

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