Datasheet

8−22
SLLS535E − April 2008TUSB6250
• The UBM (USB buffer manager, a DMA engine on the USB side) of the TUSB6250 loads the data into
either the X-buffer or Y-buffer, depending on the following conditions:
− If DBUF = 1, TOGLE = 0, and the data PID = DATA0:
The UBM loads the data into the X-buffer of the out-endpoint data buffer (4K-byte EDB) and updates
the X-buffer byte-count information in the OEPBCNLX_n and OEPBCNHX_n registers.
− If DBUF = 1, TOGLE = 1, and the data PID = DATA1:
The UBM loads the data into the Y-buffer of the out-endpoint data buffer (4K-byte EDB) and updates
the Y-buffer byte-count information in the OEPBCNLY_n and OEPBCNHY_n registers.
• The MCU is alerted with an ACK interrupt to the current out-endpoint. The firmware processes the
received data packet stored in either the X-buffer or Y-buffer of the out-endpoint data buffers.
• Once the firmware finishes the processing, the out-endpoint data buffer is empty. The firmware then clears
the NAK bit to 0 to indicate to the TUSB6250 hardware that it is ready for the next host-out request.
8.10.13 OEPSIZXY_n: Output Endpoint X/Y-Buffer Size Register (n = 1 to 4) (XDATA at F01C, F02C,
F03C, F04C)
The OEPSIZXY_n register contains the X- and Y-buffer size for the specified output endpoint.
76543210
S10 S9 S8 S7 S6 S5 S4 S3
R/W R/W R/W R/W R/W R/W R/W R/W
BIT
NAME RESET FUNCTION
7−0 S[10:3] 00h X- and Y-buffer size in bytes: S[10:3] is padded with zeros (S[10:3] & 000) to produce an 11-bit value.
Size is 0 to 1024 in increments of eight.
8.10.14 OEPBBADRY_n: Output Endpoint Y-Buffer Base Address Register (n = 1 to 4) (XDATA at F01D,
F02D, F03D, F04D)
The OEPBBADRY_n register contains the Y-buffer base address for the specified output endpoint.
76543210
A11 A10 A9 A8 A7 A6 A5 A4
R/W R/W R/W R/W R/W R/W R/W R/W
BIT NAME RESET FUNCTION
7−0 A[11:4] 00h This is the middle 8-bit value of the complete (1110 & A[11:4] & 0000) 16-bit Y-buffer base address.
See Figure 8−4. This value can be set only by the MCU. The UBM or the MCU uses this value as the
start address of Y-buffer for a given transaction.
8.10.15 OEPBCNLY_n: Output Endpoint Y-Buffer Byte-Count Low-Byte Register (n = 1 to 4) (XDATA at
F01E, F02E, F03E, F04E)
The OEPBCNLY_n register contains the lower 8-bit value in the Y-buffer that is used to specify the amount
of data received in a data packet from the USB host.
76543210
C7 C6 C5 C4 C3 C2 C1 C0
R/O R/O R/O R/O R/O R/O R/O R/O
BIT NAME RESET FUNCTION
7−0 C[7:0] 00h Y-buffer byte-count: low byte