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Author Topic: Connection error  (Read 1919 times)

Jagho

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Connection error
« on: September 15, 2015, 10:37:38 »

Hi,
I ran the AstroEQ with the Gemini G-40 mount. It works great ! Thanks for your advices, Tom, but I have a little problem from time to time. When I start the system and EQMod I get connection error. Not always, sometimes.
I disconnect USB and power cable and connect them again. Power first and then USB and everything works fine.
I look at the scheme. I think to power PIC 18F14K50 from 78L05, not USB. Could it help ?

Jarek
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TCWORLD

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Re: Connection error
« Reply #1 on: September 15, 2015, 11:06:15 »

This is a well known issue. You need to connect 12V *before* the USB connection. If you do it the other way around it can cause the USB controller to crash. I have not been able to isolate the cause.

The reason for not powering the PIC from the 78L05 is entirely down to protecting the USB port in the event of a failure. If the PIC was powered by the 78L05 and if it was to ever short through, 12V could get connected to the USB port which would be very bad. Instead the PIC circuit was chosen to be powered from the USB port meaning there is no possibility of high voltage feeding back into the computer.
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Tom Carpenter (AstroEQ)

Jagho

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Re: Connection error
« Reply #2 on: September 15, 2015, 11:13:59 »

OK, I see.
Thanks for your explanation.
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