SMSC LAN9312 - Manual (Page 131)

High Performance Two Port 10/100 Managed Ethernet Switch with 32-Bit Non-PCI CPU Interface
Datasheet
SMSC LAN9312 131 Revision 1.4 (08-19-08)
DATASHEET
9.8.7 Transmitter Errors
If the Transmitter Error (TXE) flag is asserted for any reason, the transmitter will continue operation.
TX Error (TXE) will be asserted under the following conditions:
„ If the actual packet length count does not match the Packet Length field as defined in the TX
command.
„ Both TX command ‘A’ and TX command ‘B’ are required for each buffer in a given packet. TX
command ‘B’ must be identical for every buffer in a given packet. If the TX command ‘B’ words do
not match, the Ethernet controller will assert the Transmitter Error (TXE) flag.
„ Host overrun of the TX Data FIFO.
„ Overrun of the TX Status FIFO (unless TXSAO is enabled)
9.8.8 Stopping and Starting the Transmitter
To halt the transmitter, the host must set the STOP_TX bit in the Transmit Configuration Register
(TX_CFG) . The transmitter will finish sending the current frame (if there is a frame transmission in
progress). When the transmitter has received the TX status for this frame, it will clear the STOP_TX
and TX_ON bits, and will pulse the TXSTOP_INT in the
Interrupt Status Register (INT_STS) .
Once stopped, the host can optionally clear the TX Status and TX Data FIFOs. The host must re-
enable the transmitter by setting the TX_ON bit. If the there are frames pending in the TX Data FIFO
(i.e., TX Data FIFO was not purged), the transmission will resume with this data.