DM9000A
APPLICATION NOTES
Preliminary 28
Version: DM9000A-AN-V121
November 27, 2007
5.5 How to Transmit Packets
Figure 5.1 Packet Transmitting Buffer.
Before transmitting a packet, the data of the packet must save into the TX FIFO SRAM, which
is the internal SRAM address 0 ~ 0xBFF in the DM9000A MAC and to write F8H (MWCMD
REG. F8H port latched) into INDEX port firstly. Then, the length of the packet is put in TXPLH
REG. FCH for the high byte and TXPLL REG. FDH for the low byte. The final step is to set the
TXREQ (Transmit Request), Bit [0] in TCR REG. 02, for transmitting this packet.
The DM9000A will generate an interrupt at PTS Bit [1] = 1 in ISR REG. FEH, if setting Bit [1] =
1 in IMR REG. FFH, and also to set a completion flag to either TX1END Bit [2] = 1 or TX2END
Bit[3] = 1 in NSR REG. 01 in toggle to indicate that the packet is transmitted completely.
5.5.1 Packet Transmission
Step 1: check the memory 8/ 16 DATA width,
(u8) io_mode = ior ( 0xFE ) >> 7; /* ISR Bit [7] IOMODE indicating I/O DATA mode */
TX
RX
0000
0BFF
0C00
3FFF
TX Buffer
RX Buffer