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Ixiasoft
A.9.3. SFP+ Interface
Two SFP+ connectors (J5, J6) are provided on the PCIe* bracket. Each connector supports a 10 GE SFP+ hot pluggable module.
- Transceivers, x1 for each SFP+, up to 12.5 Gbps
- SMBUS (I2C), 3.3 V for SFP+ and I/O expander, level-translated 10 1.8-V with U22/U23
- IRQ of I/O expander, 3.3 V level-translated to 1.8 V with U19
Each SFP+ module has six status/control signals and two LEDs. The FPGA device does not have enough I/O pins for these signals, hence an I/O expander is used to implement these I/Os for each SFP+ connector. The I2C I/O expander is on the same I2C bus as the SFP+ module, and the I2C bus of two SFP+ modules are independent of each other.
The I/O expander used is TI TCA9534PWR. U20 is for SFP+ 0, with I2C address 7'b010_0000. U21 is for SFP+, with I2C address 7'b010_0000.
The I/O expander has 8 I/Os. The definition of the I/Os is shown in the table below. The device is controlled with I2C bus.
I/O Number | Signal | I/O Type | Function |
---|---|---|---|
P0 | SFP_RLED | Output | Red LED, indicates LOS/ERR, "0" - ON |
P1 | SFP_GLED | Output | Green LED, indicates Link, "0" - ON |
P2 | SFP_TXDIS | Output | Tx_Disable, Pulled up, Transmitter is turned off if high |
P3 | SFP_TFLT | Input | Tx_Fault, Pulled up, indicates fault when high |
P4 | SFP_RS1 | Output | Rate Select, Pulled up with 1K resistor |
P5 | SFP_RLOS | Input | Rx_LOS, Pulled up, indicates LOS when high |
P6 | SFP_RS0 | Output | Rate Select, Pulled up with 1K resistor |
P7 | SFP_PRSN | Input | Mod_ABS, Pulled up, module in place when low |
The I/Os of TCA9534 is in high impedance input mode upon power up. Hence, the module is placed in TX_Disable mode and the LEDs are off. The status changes on the I/Os are reported with an IRQ to the FPGA. Each I/O expander has its own dedicated IRQ signal.