usb question of dm6446.

WeiJiang

Expert 1080 points

Dear swami and all,

I have the same problem of below link:

http://e2e.ti.com/support/embedded/f/354/p/56689/344282.aspx

I can connect more than 3 devices in full speed mode but only 3 devices in high-speed mode.

My question is:

Is this a hardware limit or software limit? Can you please give me some clue or reasons?

Thanks a lot.

Wei

over 14 years ago

0 WeiJiang over 14 years ago

Expert 1080 points

up!!!

0 WeiJiang over 14 years ago

Expert 1080 points

up!!!!!!!!!!!!!!!!!!!!!!!!1111

0 Ravi B over 14 years ago in reply to WeiJiang

TI__Expert 7885 points

The DM6446 has only 4 tx and 4 rx endpoint. and hence there is a limitation in hardware (IP core) to connect the more number of interrupt devices (like HUB, mouse, keyboard). You can enable the interrupt endpoint scheduling feature to connect more devices.

Regards

Ravi B

0 Ravi B over 14 years ago in reply to Ravi B

TI__Expert 7885 points

This limitation is due to less number of endpoint (4 Tx and 4 Rx) and the interrupt devices connected will occupy (mostly Rx) endpoint resources permanently till the device is connected. For example one HUB, mouse and keyboard will occupy 3 Rx endpoints permanently till any of the devices is removed and left with one Rx endpoint (you can connect one flash drive).

The interrupt endpoint scheduling logic will multiplex the one endpoint for all the endpoint devices based on its periodicity.

Regards

Ravi B

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usb question of dm6446.