Communication Processor Module
MOTOROLA MPC823e REFERENCE MANUAL 16-359
USB
COMMUNICATION
16
PROCESSOR MODULE
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.
• 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.
EP
x
PTR
BIT 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
FIELD ENDPOINT INDEX POINTER 00000
R/W R/W R/W R/W R/W R/W R/W
RESET 0 00000
ADDR USB BASE + 0x00 (EP0PTR), 0x02 (EP1PTR), 0x04 (EP2PTR), 0x06 (EP3PTR)
FRAME_N
BIT 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
FIELD V RESERVED FRAME NUMBER
R/W R/W R/W R/W
RESET 00 0
ADDR USB BASE + 0x10
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