SH7619 Datasheet, PDF (320/836 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7619 Series

Section 12 Ethernet Controller Direct Memory Access Controller (E-DMAC)
12.2.10 Transmit FIFO Threshold Register (TFTR)
TFTR is a 32-bit readable/writable register that specifies the transmit FIFO threshold at which the
first transmission is started. The actual threshold is 4 times the set value. The EtherC starts
transmission when the amount of data in the transmit FIFO exceeds the number of bytes specified
by this register, when the transmit FIFO is full, or when 1-frame write is executed. When setting
this register, do so in the transmission-halt state.
Initial
Bit
Bit Name value R/W Description
31 to 11 
All 0
R
Reserved
These bits are always read as 0. The write value
should always be 0.
10 to 0 TFT10 to All 0
TFT0
R/W Transmit FIFO threshold
When setting a transmit FIFO, the FIFO must be set to
a smaller value than the specified value of the FIFO
capacity by FDR.
H'00: Store and forward modes
H'01 to H'0C: Setting prohibited
H'0D: 52 bytes
H'0E: 56 bytes
:
:
H'1F: 124 bytes
H'20: 128 bytes
:
:
H'3F: 252 bytes
H'40: 256 bytes
:
:
H'7F: 508 bytes
H'80: 512 bytes
H'81 to H'200: Setting prohibited
Note: When starting transmission before one frame of data write has completed, take care the
generation of the underflow.
Rev. 5.00 Mar. 15, 2007 Page 282 of 794
REJ09B0237-0500