cancel
Showing results for 
Search instead for 
Did you mean: 

USB Superspeed Peripherals

mamu_3907446
New Contributor

Hi,

I would like to change the packet size in the ISOC module (USBIsocSourceSink)

in the 'cyfxisosrcsink.h'  I'm changing 'CY_FX_ISO_MAXPKT' parameter from 1024 to 225.

I'm successfully program the FX3 but the device isn't enumerated.

is there any other parameter I should change in order to change packet size?

0 Likes
1 Solution
YashwantK_46
Moderator
Moderator

Hello,

Please refer to Section 4.4.8 Isochronous Transfers, more specifically 4.4.8.1. which says about the ISOC endpoint size requirements in USB 3.1 Specification from the following link: https://manuais.iessanclemente.net/images/b/bc/USB_3_1_r1.0.pdf

This section explains about the ISOC endpoint usage and requirements in SS USB.

Regards,
Yashwant

View solution in original post

0 Likes
5 Replies
YashwantK_46
Moderator
Moderator

Hello,

Along with the CY_FX_ISO_MAXPKT set to 225, you will also need to change the CY_FX_ISO_BURST to (1) as shown below:

pastedImage_0.png

This will make the device enumerate properly with an endpoint size of 224.

Regards,
Yashwant

0 Likes
mamu_3907446
New Contributor

thanks a lot!

and if I would like to change packet size to 1 byte? is it possible?

0 Likes
YashwantK_46
Moderator
Moderator

Hello,


Yes, the packet size can be set to 1 Byte as well.

But to only get one packet of 1 Byte, you can set the Mult Setting CY_FX_ISO_PKTS to (1).

Regards,
Yashwant

mamu_3907446
New Contributor

Great, thanks.

what is the theory behind the correlation  between those different parameters :

1. max packets

2. ISOC packets

3. max burst size

0 Likes
YashwantK_46
Moderator
Moderator

Hello,

Please refer to Section 4.4.8 Isochronous Transfers, more specifically 4.4.8.1. which says about the ISOC endpoint size requirements in USB 3.1 Specification from the following link: https://manuais.iessanclemente.net/images/b/bc/USB_3_1_r1.0.pdf

This section explains about the ISOC endpoint usage and requirements in SS USB.

Regards,
Yashwant

View solution in original post

0 Likes