Connection for USB to PIC18F4550

[edmondren_89]

Hi there,

my intention is to connect pc to PIC18F4550,


i had already purchased USB cable type A to B,

can someone give me the schematic to connect the USB socket to the microcontroller ?


you may email to me at edmondren_89@hotmail.com


Best regards,

Edmond

 

[sreepss]

U just look in to the datasheet of 18F4550/2550 u will get more information abt the controller in detail

Datsheet sect 17

and do the following

1.must connect a 470pF capacitor from its 18 th PIn to Ground(Vusb)
2.Connect .1uF,.01uF, and a .001 ud across the supply for decoupling

 

[edmondren_89]

what does the decoupling for?..

by the way do you have the schematic ?

Can 4M Hz crystal oscillator be used for 18F4550 ? or should i use 20Mhz

 

[nsw1216]

edmondren_89,

20 MHz crystal would be recommended in your circuit so that the pic will perform in full speed.

regards,
nsw1216

 

[sreepss]

Actually the USB is astandrad module, it requirs a standard inpit frequncy for its operation (Only if u are using the USB module.) You can use varity of oscillators, but you rtequired to change some configuration settings in the USBCON

Pls Refer the datasheet Section 2.3 Oscillator Configuration for USB Page 29


Actually the Decoupling is used to Stabilize the system performance. (Data transfer rate was higher in the USB than any other system) 3 decoupling Capacitors are used why because, it can cover a range of frequencies

 

[nsw1216]

sreepss,

Is it stated in datasheet about the usage of decoupling ?

 

[sreepss]

Datasheet describes the use of Decap, But in a microchip App note(I forgot the doc Number) it is mentioned.. And with out this dcap, i faced many problems

 

[nsw1216]

Sreepss,

Thanks for the information.