Motorola MPC823e Reference Manual page 813

You must initialize certain parameter RAM values before the USB controller is enabled.
Other values are initialized by the communication processor module. Once initialized, the
parameter RAM values do not need to be accessed by your software. They must only be
modified when there is no USB activity.
• EPxPTR—The endpoint parameters block pointers are index pointers to the endpoint's
parameter block. The parameter block can be allocated to any address divisible by 32
in the dual-port RAM. The format of the endpoint parameter block is shown in
Table 16-35.
x
EP PTR
BIT 0 1 2
FIELD
R/W
RESET
ADDR USB BASE + 0x00 (EP0PTR), 0x02 (EP1PTR), 0x04 (EP2PTR), 0x06 (EP3PTR)
• FRAME_N—The frame number entry is updated by the USB controller when a SOF
token is received. The entry contains 11 bits representing the frame number. An SOF
interrupt is issued when this entry is updated. You must initialize this parameter to zero
before operating the USB controller.
FRAME_N
BIT 0 1 2
FIELD V RESERVED
R/W R/W R/W
RESET 0 0
ADDR
MOTOROLA
3 4 5 6 7
ENDPOINT INDEX POINTER
R/W
0
3 4 5 6 7
USB BASE + 0x10
MPC823e REFERENCE MANUAL
Communication Processor Module
8 9 10 11 12
0 0
R/W R/W R/W
0 0
8 9 10 11 12
FRAME NUMBER
R/W
0
13 14 15
0 0 0
R/W R/W
0 0 0
13 14 15
16-359