User Manual

95
AT8xC5122/23
4202E–SCR–06/06
USB Controller The AT8xC5122D implements a USB device controller supporting Full Speed data
transfer. In addition to the default control endpoint 0, it provides 6 other endpoints, which
can be configured in Control, Bulk, Interrupt or Isochronous modes:
• Endpoint 0: 32-byte FIFO, default control endpoint
• Endpoint 1,2,3: 8-byte FIFO
• Endpoint 4,5: 64-byte FIFO
• Endpoint 6: 2 x 64-byte Ping-pong FIFO
This allows the firmware to be developed conforming to most USB device classes, for
example:
• USB Mass Storage Class Control/Bulk/Interrupt (CBI) Transport, Revision 1.0 -
December 14, 1998.
• USB Mass Storage Class Bulk-Only Transport, Revision 1.0 - September 31, 1999.
• USB Human Interface Device Class, Version 1.1 - April 7, 1999.
• USB Device Firmware Upgrade Class, Revision 1.0 - May 13, 1999.
USB Mass Storage Classes
USB Mass Storage Class CBI
Transport
Within the CBI framework, the Control endpoint is used to transport command blocks as
well as to transport standard USB requests. One Bulk-Out endpoint is used to transport
data from the host to the device. One Bulk-In endpoint is used to transport data from the
device to the host. And one interrupt endpoint may also be used to signal command
completion (protocol 0); it is optional and may not be used (protocol 1).
The following configuration adheres to these requirements:
• Endpoint 0: 8 bytes, Control In-Out
• Endpoint 4: 64 bytes, Bulk-Out
• Endpoint 5: 64 bytes, Bulk-In
• Endpoint 1: 8 bytes, Interrupt In
USB Mass Storage Class Bulk-
Only Transport
Within the Bulk-Only framework, the Control endpoint is only used to transport class-
specific and standard USB requests for device set-up and configuration. One Bulk-Out
endpoint is used to transport commands and data from the host to the device. One Bulk-
In endpoint is used to transport status and data from the device to the host. No interrupt
endpoint is needed.
The following configuration adheres to these requirements:
• Endpoint 0: 8 bytes, Control In-Out
• Endpoint 4: 64 bytes, Bulk-Out
• Endpoint 5: 64 bytes, Bulk-In
USB Device Firmware
Upgrade (DFU)
The USB Device Firmware Update (DFU) protocol can be used to upgrade the on-chip
program memory of the AT8xC5122D. This allows the implementation of product
enhancements and patches to devices that are already in the field. Two different config-
urations and description sets are used to support DFU functions. The Run-Time
configuration co-exists with the usual functions of the device, which may be USB Mass
Storage for the AT8xC5122D. It is used to initiate DFU from the normal operating mode.
The DFU configuration is used to perform the firmware update after device re-configura-
tion and USB reset. It excludes any other function. Only the default control pipe
(endpoint 0) is used to support DFU services in both configurations.