Sharp LH79524 - OUT Maximum Packet Size Register EP 1 and 2 (OUTMAXP); Table 17-34. OUTMAXP Register; Table 17-35. OUTMAXP Fields

Universal Serial Bus Device LH79524/LH79525 User’s Guide
17-26 Version 1.0
17.2.3.6 OUT Maximum Packet Size Register EP 1 and 2 (OUTMAXP)
OUTMAXP is programmed with the maximum packet size for transactions through the cur-
rently-selected OUT endpoint — in units of 8 bytes, except that a value of 128 sets the
maximum packet size to 1023 (the maximum size for an isochronous packet) rather than
1024. In setting this value, note the constraints placed by the USB Specification on packet
sizes for Bulk, Interrupt and Isochronous transactions in Full-speed operations.
The value written to this register should match the wMaxPacketSize field of the Standard
Endpoint Descriptor for the associated endpoint (see Universal Serial Bus Specification
Revision 2.0, Chapter 9). A mismatch could cause unexpected results.
The total amount of data represented by the value written to this register must not exceed
the FIFO size for the OUT endpoint, and should not exceed half the FIFO size if double-
buffering is required. If a value greater than the OUT FIFO size (see Table 17-2) for the
endpoint is written to this register, the value will be automatically changed to the OUT FIFO
size. If the value written to this register is less than or equal to half the OUT FIFO size, two
OUT packets can be buffered.
Table 17-34. OUTMAXP Register
BIT 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
FIELD ///
RESET 0000000000000000
RW RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO
BIT 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
FIELD /// OUTMAXP
RESET 0000000000000000
TYPE RO RO RO RO RO RO RO RO RW RW RW RW RW RW RW RW
ADDR
0xFFFF5000 + 0x04C
(with the INDEX register set to OUT endpoint 1 or 2)
Table 17-35. OUTMAXP Fields
BITS NAME FUNCTION
31:8
/// Reserved Reading returns 0. Write the reset value.
7:0 OUTMAXP OUT Maximum Packet Size Maximum Packet Size/transaction