SH7670 Datasheet, PDF (745/1292 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7670 Series

Bit
Bit Name
9
DBLB
Section 17 USB 2.0 Host/Function Module (USB)
Initial
Value R/W
0
R/W
Description
Double Buffer Mode
Selects either single or double buffer mode for the
FIFO buffer used by the selected pipe.
0: Single buffer
1: Double buffer
This bit is valid when PIPE1 to PIPE5 are selected.
When software has set this bit to 1, this module
assigns two planes of the FIFO buffer size specified
by the BUFSIZE bits in PIPEBUF to the selected
pipe.
Specifically, the following expression determines the
FIFO buffer size assigned to the selected pipe by this
module.
(BUFSIZE + 1) * 64 * (DBLB + 1) [bytes]
When software has set this bit to 1 and the selected
pipe is in the transmitting direction, this module does
not generate the BRDY interrupt.
For details, refer to (1) BRDY Interrupt under section
17.4.2, Interrupt Functions.
Modify these bits while CSSTS is 0 and PID is NAK
and before the pipe is selected by the CURPIPE bits.
To modify these bits after completing USB
communication using the selected pipe, write 1 and
then 0 to ACLRM continuously through software to
clear the FIFO buffer assigned to the selected pipe
while the CSSTS, PID, and CURPIPE bits are in the
above-described state.
Before modifying these bits after modifying the PID
bits for the selected pipe from BUF to NAK, check
that CSSTS and PBUSY are 0. However, if the PID
bits have been modified to NAK by this module,
checking PBUSY through software is not necessary.
Rev. 1.00 Nov. 14, 2007 Page 719 of 1262
REJ09B0437-0100