SH7713 Datasheet, PDF (747/904 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7700 Series

Section 19 Ethernet Controller Direct Memory Access Controller (E-DMAC)
(b) Receive Descriptor 1 (RD1)
In RD1, the user specifies the data length of a receive buffer usable by the corresponding
descriptor. After reception of a frame, RD1 indicates the length of a frame received by the
E-DMAC.
The user should set RD1 before the start of a read by the E-DMAC.
Initial
Bit
Bit Name Value R/W Description
31 to 16 RBL
All 0
R/W Receive Buffer Data Length (in bytes, to be specified
on 16-byte boundary)
Set the length of data that can be received by the
corresponding receive buffer in bytes.
Set a receive buffer length on a 16-byte boundary
(with bits 19 to 16 cleared to 0).
In single-frame/single-buffer (descriptor) operation,
the maximum receive frame length excluding CRC
data is 1514 bytes. When specifying a receive buffer
length, set 1520 bytes (H'05F0), which is determined
considering the maximum receive frame length and a
16-byte boundary.
15 to 0 RDL
All 0
R
Receive Data Length
Indicate the data length of a receive frame stored in
the receive buffer.
Receive data transferred to the receive buffer does
not include CRC data (4 bytes) placed at the end of a
frame. As a receive frame length, the number of bytes
(valid data bytes) not including CRC data are
reported.
In single-frame/multi-buffer (descriptor) operation,
only the receive data length of the last descriptor is
valid. The receive data length of an intermediate
descriptor has no meaning.
(c) Receive Descriptor 2 (RD2)
RD2 indicates the start address of the corresponding 32-bit width receive buffer. Set the start
address of a receive buffer on a longword boundary. When an SDRAM is connected, set the start
address of a receive buffer on a 16-byte boundary.
The user should set RD2 before the start of a read by the E-DMAC.
Rev.1.50 Aug. 30, 2006 Page 707 of 860
REJ09B0288-0150