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Forum Index : Microcontroller and PC projects : USB on Micromite Plus

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circuit
Senior Member

Joined: 10/01/2016
Location: United Kingdom
Posts: 290

Posted: 03:35pm 03 Nov 2018

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I note that the USB interface on the Micromite Plus chips includes a pin marked USB+5v (leg 34 on the 64 pin and leg 54 on the 100 pin chip. What is the purpose of this pin? I assume that one only needs USB D- and USB D+ with a ground connection to get the USB link working. I thought that the USB 5 Volt line was there to provide power to peripheral devices - I am assuming that the Micromite Plus cannot actually be powered via this pin. Obviously I am missing something here otherwise the pin would not be there, but what am I missing or failing to understand?Edited by circuit 2018-11-05

matherp
Guru

Joined: 11/12/2012
Location: United Kingdom
Posts: 10572

Posted: 03:59pm 03 Nov 2018

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It is all in the PIC32MX470 manual. VBUS tells the PIC whether it is acting as a USB host or slave. The MM+ doesn't support host mode but Geoff uses it to know if the USB connection is plugged in and therefore whether to run the USB code which adds overhead to the processing and therefore isn't run if not needed

circuit
Senior Member

Joined: 10/01/2016
Location: United Kingdom
Posts: 290

Posted: 06:57pm 03 Nov 2018

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Succinctly clear, Peter, many thanks. I guessed that there would be some ingenious concept behind it.

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