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by daytona
Wed Sep 12, 2018 7:17 am
Forum: HATs and other add-ons
Topic: PoE HAT - USB Ports not working - over-current (FIXED - New Hardware Release)
Replies: 315
Views: 40306

Re: PoE HAT - USB Ports not working - over-current

Because the regulator operates at a fairly low frequency, each time it switches it moves quite a large chunk of energy into the three USB reservoir caps via the current limiting switch: this large instantaneous current is fooling the switch into thinking that a genuine over-current event is occurri...
by daytona
Thu Sep 06, 2018 10:14 am
Forum: HATs and other add-ons
Topic: PoE HAT - USB Ports not working - over-current (FIXED - New Hardware Release)
Replies: 315
Views: 40306

Re: PoE HAT - USB Ports not working - over-current

... It's not obvious what "feature" of the PoE 5V is causing the issue. Really? No, it is. The_Raven already narrowed the problem. The issue is poor design and testing. I assume, the final layout, the real PCB manufactured was never tested since too many are reporting a near no-function. Maybe a la...
by daytona
Wed Sep 05, 2018 10:26 pm
Forum: HATs and other add-ons
Topic: PoE HAT - USB Ports not working - over-current (FIXED - New Hardware Release)
Replies: 315
Views: 40306

Re: PoE HAT - USB Ports not working - over-current

I've setup the PoE Hat on a small test rig tonight feeding a dummy load. The two load resistors across the 5 volt supply sink about 1.5amps. testrig.jpg With the output capacitors fitted to the PoE HAT PCB the 5 volt output on my 'scope looks like this. (2V/div, GND at centre) scopenoise.jpg When I ...
by daytona
Wed Sep 05, 2018 7:09 am
Forum: HATs and other add-ons
Topic: PoE HAT - USB Ports not working - over-current (FIXED - New Hardware Release)
Replies: 315
Views: 40306

Re: PoE HAT - USB Ports not working - over-current

... Can everyone who's experiencing stability issues with the USB port power on PoE-equipped Pi3B+ Pis please test the devicetree overlay that sets the fan permanently running and report back. With the new devicetree the fan is running continually, there are no overcurrent warnings. With the CPU id...
by daytona
Tue Sep 04, 2018 2:35 pm
Forum: HATs and other add-ons
Topic: PoE HAT - USB Ports not working - over-current (FIXED - New Hardware Release)
Replies: 315
Views: 40306

Re: PoE HAT - USB Ports not working - over-current

The observation I've made with a Raspberry Pi3B+ and PoE HAT today is that the USB over-current change messages only occur when the fan on the PoE HAT is not running. As soon as the fan runs, the messages stop. I've had it running on my desk all day, the CPU had been sitting at about 50degC so the H...

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