3 functional description, 1 interrupts, 4 software interface – Freescale Semiconductor MCF5480 User Manual
Page 921: 1 device initialization, Usb endpoint, Functional description -47, Interrupts -47, Software interface -47, Device initialization -47
Functional Description
MCF548x Reference Manual, Rev. 3
Freescale Semiconductor
29-47
29.2.5.12 USB Endpoint n Last Write Frame Pointer (EPnLWFP)
29.3
Functional Description
29.3.1
Interrupts
Please see
Chapter 13, “Interrupt Controller,”
for information on the USB interrupts.
29.4
Software Interface
This section provides information pertinent to programming the device. It includes information to
configure, program, and debug the device.
29.4.1
Device Initialization
During device initialization, user software prepares the USB 2.0 device datapath for processing. This
process is performed at two different times: hard reset and when the device is first connected to the USB.
The device must be able to detect a connection event to the USB. This operation is described in the USB
Specification, Chapter 7 (Electrical Specification).
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
R
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
W
Reset
Uninitialized
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
R
0
0
0
0
LWFP
W
Reset
Uninitialized
0
0
0
0
0
0
0
0
0
0
0
0
Reg
Addr
MBAR + 0xB46C (EP0LWFP); 0xB49C (EP1LWFP); 0xB4CC (EP2LWFP); 0xB4FC (EP3LWFP);
0xB52C( EP4LWFP); 0xB55C (EP5LWFP); 0xB58C (EP6LWFP)
Figure 29-52. USB Endpoint n Last Write Frame Pointer (EPnLWFP)
Table 29-47. EPnLWFP Field Descriptions
Bits
Name
Description
31–12
—
Reserved, should be cleared.
11–0
LWFP
Last write frame pointer. FIFO-maintained pointer that indicates the start of the last frame
written into the FIFO. The LWFP can be read and written for debug purposes. For the frame
retransmit function, the LRFP indicates which point to begin retransmission of the data
frame. For the frame discard function, the LWFP divides the valid data region of the FIFO
(the area in-between the read and write pointers) into framed and unframed data. Data
between the LFP and write pointer is of an incomplete frame, while data between the read
pointer and the LWFP has been received as whole frames. When EPnFCR[FRM] is not set,
then this pointer has no meaning.