Cypress Semiconductor SL811HS Manual do Utilizador descarregar pdf (Página 42)

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: 42

6. ERROR RECOVERY MANAGEMENT

Error recovery is the responsibility of the host controller. The SL811HS host controller provides

error detection and status for USB transactions. Host software should be written to recover

from reported error conditions.

6.1. SL811HS Error Conditions

Error conditions are reported in the Status register. An interrupt can be generated on an error

condition by enabling the Interrupt bit in the Interrupt control register. Polling the USBStatus

USB Status:

0x01 ACK

0x02 Device Error Bit

0x04 Device Time out

0x08 Toggle bit

0x10 SET_UP packet bit (Not used in SL11H)

0x20 Overflow bit

0x40 Device returned NAK to last transaction

0x80 Device returned STALL

Table 7: Error Conditions

Error Conditions SL811HS

Packet ID Check √

Bit Stuff Error √

Bus Time-out √

False EOP √

CRC Check √

Babble √

Loss of Activity √

6.2. Data Toggle Error

Data transfers on the USB use Data0 and Data1 packets so that the receiver can remain

synchronized with the transmitter. If synchronization is lost, a Data Toggle Error condition

occurs. Data Toggle Error reporting is supported for Interrupt, Bulk, and Control transfers only.

Software is required to recover from a Data Toggle Error whenever it occurs. SL811HS

provides bit-3 of USBStatus Register to report whenever a Data0 and Data1 mismatch occurs.

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Cypress Semiconductor SL811HS Manual do Utilizador Página 42