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USB and Speed

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LetThereBeLight

Joined: 15 Jul 2007
Posts: 3

USB and Speed

Posted: Fri Jul 27, 2007 6:55 am

Hi every one

I have a little trouble with USB and speed.

First i use HID demo program to build my own USB program.
we can reed in description :

Code:

//// - On a full speed device, max polling rate is 1 transaction ////
//// per 1ms. This is 64000 bytes per second (64 byte packets ////
//// every 1ms).

but also in HID descriptor :

Code:

//endpoint descriptor

USB_DESC_ENDPOINT_LEN, //length of descriptor ==35
USB_DESC_ENDPOINT_TYPE, //constant ENDPOINT (ENDPOINT 0x05) ==36
0x01, //endpoint number and direction (0x01 = EP1 OUT) ==37
0x03, //transfer type supported (0x03 is interrupt) ==38
USB_EP1_RX_SIZE,0x00, //maximum packet size supported ==39,40
10 //polling interval, in ms. (cant be smaller than 10) ==41

so wich one is right ? 10 or 1 ?
So HID is limited to 64*1000 bytes / s , that is pretty slow !

Also i am looking for a ISOCHRONOUS exemple to reach USB2 speeds .
Any one could advise me anything helpfull ?

thank you all.

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