| View previous topic :: View next topic |
| Author |
Message |
prayami
Joined: 22 Dec 2004
Posts: 78
|
| Fast USB with PIC18F4550 |
 Posted: Mon Sep 26, 2005 7:35 pm |
 |
|
Hi..I got the latest version of the CCS compiler few weeks ago. I have
tested the example program for USB successfully.
Question: How to increase speed?
(1)
Now I want to increase the speed of sending data. On the datasheet of
PIC18F4550, it is written that its speed is 12Mb/S. Is that mean that
I can send 12000 MegaBytes/millisecond ?
In the example file "ex_usb_hid.c" following is written....
| Quote: |
//// - On a full speed device, max polling rate is 1 transaction ////
//// per 1ms. This is 64000 bytes per second (64 byte packets ////
//// every 1ms). ////
|
Is that mean that, I can send only 64bytes per second?
(2)
There is code for debug on RS232. Can disable that any way or I have
modified that at all the places?
(3)
I think to send whole 8 bit array of 8 elements like that following
| Quote: |
usb_put_packet(1, out_data, 8, USB_DTS_TOGGLE);
|
Is this the only possible way to make it faster?
Can anybody tell me to increase the speed all possible way? The code is
little bit complex so it is hard for me to understand.
Thanks..... |
|
 |
PCM programmer
Joined: 06 Sep 2003
Posts: 21708
|
|
| Posted: Mon Sep 26, 2005 8:53 pm |
|
|
| Quote: |
On the datasheet of PIC18F4550, it is written that its speed is 12Mb/S.
Is that mean that I can send 12000 MegaBytes/millisecond ? |
http://www.everythingusb.com/usb2/faq.htm |
|
|
Mark
Joined: 07 Sep 2003
Posts: 2838
Location: Atlanta, GA
|
|
| Posted: Mon Sep 26, 2005 9:47 pm |
|
|
You are confusing Mb (megabits) with MB (megabytes).
Regardless of all that, you aren't going to achieve a high transfer rate unless you use Isochronous Transfer were the max packet size is 1023 for full speed versus the 64 bytes. |
|
|
|
FAQ 
Search
Register
Profile 
Log in to check your private messages 
Log in
