PIC's and USB

Aug 31, 2008 1 Replies

I downloaded some stuff on how to use USB from:



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I want to make a PIC act as an HID keyboard, but I've come up with a couple questions before I get too deep into this.


1) Most of the schematics I see show an external xtal running the clock; is this necessary. or is the onboard clock adequate for short data xfers?


2) Prof. Minch's code simply keeps sending the same text over and over. What's the simplest way to have the computer send a char to the PIC saying 'OK, send me the next batch!'.



Thanks. This stuff is like trying to swallow an elephant!


USB clocks need to be very accurate, so the external crystals are the way to go.

I got a USB development kit from Microchip that can be configured as a keyboard, mouse, game port, or a USB to Serial converter. They have pretty good tutorials, but I attended an introductory class on USB when I went to their MASTERs conference a few years ago, and then I went to another local full-day training class that helped me understand a bit more.

The microchip forums are also good resources for USB questions, if you are using Microchip products such as the PIC18F4550.

You might check the Microchip website for a training class in USB From Scratch (390 USB). There are some coming up soon in Cleveland, Boston, and LA.

Another good USB resource is

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Paul

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