Rainbow Electronics AT89C5122 - Manual (Page 99)

99
AT8xC5122/23
4202E–SCR–06/06
Configuration
General Configuration • USB controller enable
Before any USB transaction, the 48 MHz required by the USB controller must be cor-
rectly generated (Section "Clock Controller", page 41).
The USB controller should be then enabled by setting the USBE bit in the USBCON
register.
• Set address
After a Reset or a USB reset, the software has to set the FEN (Function Enable) bit in
the USBADDR register. This action will allow the USB controller to answer to the
requests sent at the address 0.
When a SET_ADDRESS request has been received, the USB controller must only
answer to the address defined by the request. The new address should be stored in the
USBADDR register. The FEN bit and the FADDEN bit in the USBCON register should
be set to allow the USB controller to answer only to requests sent at the new address.
• Set configuration
The CONFG bit in the USBCON register should be set after a SET_CONFIGURATION
request with a non-zero value. Otherwise, this bit should be cleared.
Endpoint Configuration • Selection of an Endpoint
The endpoint register access is performed using the UEPNUM register. The following
registers
correspond to the endpoint whose number is stored in the UEPNUM register. To select
an Endpoint, the firmware has to write the endpoint number in the UEPNUM register.
– UEPSTAX,
– UEPCONX,
– UEPDATX,
– UBYCTX,
Figure 53. Endpoint Selection
UEPNUM
Endpoint 0
Endpoint 6
UEPSTA0 UEPCON0 UEPDAT0
UEPSTA6 UEPCON6 UEPDAT6
0
1
2
3
4
5
6
SFR Registers
UEPSTAX UEPCONX UEPDATX X
UBYCT0
UBYCT6
UBYCTX