Cypress Semiconductor SL811HS Manual do Utilizador descarregar pdf (Página 43)

Cypress Semiconductor Corporation

SL811HS and SL811HST: Application Notes

and specifications contained in this document are subject to change without

notice.

Date: 07/26/01

Revision: 1.21

Page: 43

6.3. Bus Timeout Error

A corrupted Token, Data, or handshake results in a Bus Timeout error, which is reported in the

status register. This can result in a retry of the same Data toggle setting.

6.4. Babble and Loss of Activity (LOA)

On USB Bus, the Babble condition is reported in the Status register. When bit 2 is set in the

interrupt enable register, the babble condition causes an interrupt. This interrupt only occurs

during the period between the EOF2 and the next SOF token generation. See chapter 5 in

USB Specification v1.1 for more details.

The SL811HS is able to detect a babble condition on bit-2 of the Interrupt Status (IntStatus

=0x0d). When the babble condition is detected, SL811HS will be prevented from sending any

packets during EOF2 time frame. SL811HS must discontinue the transactions prior to the end

of packet to ensure that no bus activity occurs at the end of frame.

Loss of Activity (LOA) is similar to Babble. A device starting a packet transfer followed by a

constant J or K state on the bus and no EOP characterizes LOA. LOA, like Babble, has the

potential to deadlock the bus and must be prevented.

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