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Author Topic: pic18f4550 with usb and icsp interface  (Read 6542 times)

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Offline junior000Topic starter

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pic18f4550 with usb and icsp interface
« on: August 01, 2008, 12:20:20 PM »
hi ppl,

        i have designed a board with icsp and usb interface.are there any mistakes or are there any room for improvement

http://bp3.blogger.com/_een4QiFVyl4/SJNTC4_XNkI/AAAAAAAAAww/P-Wxvof8zNQ/s1600-h/pic18.jpg
view my tutorials at


www.myfirstbot.blogspot.com

Offline Admin

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Re: pic18f4550 with usb and icsp interface
« Reply #1 on: August 03, 2008, 04:23:52 PM »
Whoa I didn't know PIC's had built in USB! I wish the bigger AVR's had it . . .

Anyway, it appears your USB is missing both ground and power:
http://www.sixca.com/eng/articles/usbdaq/

And you probably want a regulated power and ground bus for the sensor inputs.

Offline paulstreats

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Re: pic18f4550 with usb and icsp interface
« Reply #2 on: August 03, 2008, 05:13:47 PM »
Quote
Whoa I didn't know PIC's had built in USB! I wish the bigger AVR's had it .

all of the newest pics (~ 1yr) have built in USB. They all have built in pll to bring the oscillator up to speed

(By the way Junior000, I just realised that when I was reviewing the USB on the 18f4550 that it is best to use a 4mhz crystal just because of how the pll loops work. Dont worry, you can actually run the mcu up to 40mhz with the 4mhz crystal with the usb side going through another post loop to produce 90mhz communication scales).

There are also other ways to wire the usb too so that you can produce interrupts on connectivity, power sourcing from the usb host etc....

Also for other people only used the the 16f series of PIC, its really worth upgrading to the 18F series. The 18F series are usually pin to pin and code to code compatable with a 16F PIC (PIC16F877A is pin to pin compatable with the PIC18F4550 - it just manages to extend the functionality of some of the pins).

Also anything above the 16F series comes with a free C compiler provided by microchip. (anything above the 16F series has extended assembly commands making it more C compatable). They also feature hardware multiplier chains for faster mathematics.

No, I dont work for microchip but I think that the entry level 16F series of controllers gives modern developers a bad experience what with having to pay for a c compiler, having to buy an expensive programmer, not being self programming etc....   the 18F series are as easy to use if not easier and should be made the new entry level devices (scrap the 16F series)

;D ;D ;D ;D    RANTING OVER!!!!    ;D ;D ;D ;D

 


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