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dwc2 ffb40000.usb Overcurrent change detected

Honored Contributor I

I get the message when writing to OTG/USB (de0-nano-soc)  


dwc2 ffb40000.usb Not connected 

dwc2 ffb40000.usb Overcurrent change detected  

-- then my attached storage is gone till the next reboot  


- while investigating i have removed the supply to the USB device & am powering externally  

therefore there should be NO over current (current to external device is <100ma so should still not have an issue ) 


there are no devices being powered off the board - only load is the fpga & support circuitry on the board  

(running both processors {linux kernel 4.4.0) , one instance of NIOSII & one of msgdma)  

works fine when writing to local SDcard... 


next guess is a heating issue - as it seems to function while cold but within 5-10min it fails as above .. .. 


any hints ? should i be looking at heatsinks & fans (uuggh) ?
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Honored Contributor I

sigh ... switch mode power supply issue .. 

added some large capacitors / & everything is fine .,.