AM335x USB ACK response

UNA

Hi,

I have question about the sample code below.

/AM335X_StarterWare_02_00_01_0/\examples/evmAM335x/usb_dev_msc/usb_dev_msc.c

I think that USB controller will return ACK (or NAK) automatically, when USB device receved Token and Data Paket from USB host. It is H/W control.

However, In the above source code, It seems that S/W returned ACK to USB host by USBDevEndpointDataAck() when DMA_MODE was not defined.

When CPPI DMA not used, do I have to control ACK by software?

Best regards,

Chi

0 Vineeth Balan over 11 years ago

Hi Chi,

The USB controller will return a packet level ACK/NAK without software intervention. This is usually same for any controller implementation.

USBDevEndpointDataAck() - this is used for transaction level acknowledgements.

0 UNA over 11 years ago in reply to Vineeth Balan

Hi, Vineeth

Thank you for your reply.

I understood that ACK/NAK(Handshake packet) response is H/W control.

So, USBDevEndpointDataAck() is not returning a ACK packet.

Is my understanding correct?

Best regards,

Chi

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