USB host does not send out the PING packet

[iscylinfromtw]

I'm using the USB host mode of RT1060. When I send a bulk out, I cannot see the PING packet around the DATA packet. I ensure the status of qTD token has enabled the Ping State (bit 0).

BTW, I'm not sure the PING packet is the key point to reduce the ACK time. Does someone could give me some suggestion? 

[iscylinfromtw]

You are right. If I send out the data size more than the FIFO size of USB device, USB host will start to issue a PING packet to check the receiving status.

Do you have any suggestion about how to improve the ACK time? When I tested in the Windows with same USB device, the ACK time does not over 1ms.

[jingpan]

Hi,

But I think you should use the Time Stamp column if you want to know when ACK come back. Isn't it?

Regards,

Jing

[iscylinfromtw]

OK, Maybe I need to take a look the descriptions of the USB packet analyzer.

[jingpan]

Hi @iscylinfromtw ,

PING packet is not necessary during a transaction. First, USB host send a OUT packet and DATA. If the USB device return a NAK or NYET, USB host will begin to send PING. IF return ACK, it needn't to send PING.

Regards,

Jing