SH7670 Datasheet, PDF (689/1292 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7670 Series

Section 17 USB 2.0 Host/Function Module (USB)
Initial
Bit
Bit Name
Value R/W Description
14
BCLR
0
R/W*¹ CPU Buffer Clear
This bit should be set to 1 to clear the FIFO buffer on
the CPU side for the selected pipe.
0: Invalid
1: Clears the buffer memory on the CPU side.
When double buffer mode is set for the FIFO buffer
assigned to the selected pipe, this module clears
only one plane of the FIFO buffer even when both
planes are read-enabled.
When the selected pipe is the DCP, setting BCLR to
1 allows this module to clear the FIFO buffer
regardless of whether the FIFO buffer is on the CPU
side or SIE side. To clear the buffer on the SIE side,
set the PID bits for the DCP to NAK before setting
BCLR to 1.
When the selected pipe is in the transmitting
direction, if 1 is written to BVAL and BCLR bits
simultaneously, this module clears the data that has
been written before it, enabling transmission of a
zero-length packet.
When the selected pipe is not the DCP, writing 1 to
this bit should be done while FRDY indicates 1 (set
by this module).
13
FRDY
0
R
FIFO Port Ready
Indicates whether the FIFO port can be accessed by
the CPU (DMAC).
0: FIFO port access is disabled.
1: FIFO port access is enabled.
In the following cases, this module sets FRDY to 1
but data cannot be read via the FIFO port because
there is no data to be read. In these cases, set BCLR
to 1 to clear the FIFO buffer, and enable
transmission and reception of the next data.
• A zero-length packet is received when the FIFO
buffer assigned to the selected pipe is empty.
• A short packet is received and the data is
completely read while BFRE is 1.
Rev. 1.00 Nov. 14, 2007 Page 663 of 1262
REJ09B0437-0100