High Performance Two Port 10/100 Managed Ethernet Switch with 32-Bit Non-PCI CPU Interface
Datasheet
CSR Read Auto
CSR ReadIncrement /
Decrement
Write | Write | | |
Command | Command | | |
Register | Register | | |
min wait period | min wait period | min wait period |
| | |
CSR_BUSY = 1 | | CSR_BUSY = 1 |
Read | Read | | |
Command | Command | | |
Register | Register | | |
CSR_BUSY = 0 | CSR_BUSY = 0 |
Read Data | last | No | Read Data |
data? | | Register |
Register
Yes
Write
Command
Register
Read Data
Register
Figure 6.2 Switch Fabric CSR Read Access Flow Diagram
6.2.3Flow Control Enable Logic
Each switch fabric port (0,1,2) is provided with two flow control enable inputs per port, one for transmission and one for reception. Flow control on transmission allows the transmitter to generate back pressure in half-duplex mode, and pause packets in full-duplex. Flow control in reception enables the reception of pause packets to pause transmissions.
The state of these enables is based on the state of the ports duplex and Auto-negotiation settings and the values of the corresponding Manual Flow Control register (Port 1 Manual Flow Control Register (MANUAL_FC_1), Port 2 Manual Flow Control Register (MANUAL_FC_2), or Port 0(Host MAC) Manual Flow Control Register (MANUAL_FC_MII)). Table 6.1 details the switch fabric flow control enable logic.
When in half-duplex mode, the transmit flow control (back pressure) enable is determined directly by the BP_EN_x bit of the ports manual flow control register. When Auto-negotiation is disabled, or the MANUAL_FC_x bit of the ports manual flow control register is set, the switch port flow control enables during full-duplex are determined by the TX_FC_x and RX_FC_x bits of the ports manual flow control
Revision 1.4 (08-19-08) | 58 | SMSC LAN9312 |
| DATASHEET | |