Section 10 Ethernet Controller Direct Memory Access Controller (E-DMAC)
Rev. 2.00 Mar 09, 2006 page 451 of 906
REJ09B0292-0200
Transmit Descriptor 1 (TD1):
Specifies the transmit buffer length (maximum 64 kbytes).
Bits 31 to 16—Transmit Buffer Data Length (TDL): These bits specify the valid transfer byte
length in the corresponding transmit buffer.
Note: When the one frame/multi-buffer system is specified (TD0 and TFP = 10 or 00), the
transfer byte length specified in the descriptors at the start and midway can be set in byte
units.
Bits 15 to 0—Reserved: The bits are always read as 0. The write value should always be 0.
Transmit Descriptor 2 (TD2):
Specifies the 32-bit transmit buffer start address.
Note: The transmit buffer’s start address setting must be aligned with a longword boundary.
However, when SDRAM is connected, the setting must be aligned with a 16-byte
boundary.
Bits 31 to 0—Transmit Buffer Address (TBA)
Receive Descriptor
Figure 10.3 shows the relationship between a receive descriptor and the receive buffer. In frame
reception, the E-DMAC performs data rewriting up to a receive buffer 16-byte boundary,
regardless of the receive frame length. Finally, the actual receive frame length is reported in the
lower 16 bits of RD1 in the descriptor. Data transfer to the receive buffer is performed
automatically by the E-DMAC to give a one frame/one buffer or one frame/multi-buffer
configuration according to the size of one received frame.
Notes: 1. The descriptor’s start address setting must be aligned with an address boundary that
corresponds with the descriptor’s length as set by the E-DMAC mode register
(EDMR).
2. The receive buffer’s start address setting must be aligned with a longword boundary.
However, when SDRAM is connected, the setting must be aligned with a 16-byte
boundary. Make the setting so that the size of the receive buffer is aligned with a 16-
byte boundary.
Example:
H'0500 (= 1280 bytes)
Содержание SH7616
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Страница 706: ...Section 16 Serial I O SIO Rev 2 00 Mar 09 2006 page 680 of 906 REJ09B0292 0200 ...
Страница 820: ...Section 19 Pin Function Controller PFC Rev 2 00 Mar 09 2006 page 794 of 906 REJ09B0292 0200 ...
Страница 932: ...Appendix D Package Dimensions Rev 2 00 Mar 09 2006 page 906 of 906 REJ09B0292 0200 ...
Страница 935: ...SH7616 Hardware Manual ...