Title here
Summary here
Programming Guide
This section provides the details of the programming requirements to operate the 2x QSFP28 FMC hardware and customise functionality.
QSFP I/Os
The QSFP28 management I/O signals must be driven by the FPGA to appropriate levels in order to configure the QSFP/QSFP+/QSFP28 modules for normal operation.
Module Reset
The QSFP28 module input RESET_L allows the FPGA to reset the module. In normal operation, this input should be driven HIGH to allow the module to operate normally. A LOW pulse can be used to reset the module.
| Net | Description | FMC pin | Value for normal operation |
|---|---|---|---|
| QSFP0_RESETL_T | Port 0: Module reset (active low) | LA04_N | HIGH (1) |
| QSFP1_RESETL_T | Port 1: Module reset (active low) | LA15_N | HIGH (1) |
Low Power Mode
The QSFP28 module input LPMODE allows the FPGA to set the module to low power mode. In normal operation, this input should be driven LOW to allow the module to operate at full power.
| Net | Description | FMC pin | Value for normal operation |
|---|---|---|---|
| QSFP0_LPMODE_T | Port 0: Low Power Mode | LA11_P | LOW (0) |
| QSFP1_LPMODE_T | Port 1: Low Power Mode | LA11_N | LOW (0) |
Module Select
The QSFP28 module input MODSEL_L selects the module for I2C communication. When driven LOW, the module responds to I2C transactions on its bus. In normal operation, this should be driven LOW to enable I2C communication.
| Net | Description | FMC pin | Value for normal operation |
|---|---|---|---|
| QSFP0_MODSELL_T | Port 0: Module Select (active low) | LA04_P | LOW (0) |
| QSFP1_MODSELL_T | Port 1: Module Select (active low) | LA15_P | LOW (0) |
Note that the pins in the above tables are connected to pull-up and pull-down resistors on the mezzanine
card to ensure that the inputs to the level translators are not left floating in the case that they are not driven by
the FPGA.
Clock multiplier
The jitter-attenuating clock multiplier ( Skyworks, Si5328 ) must be configured via the PL I2C bus to enable appropriate clocks for the QSFP/QSFP+/QSFP28 modules used.
The CLK I2C bus signals are connected to the FMC pins listed in the table below:
| Net Name | Description | FMC pin |
|---|---|---|
| CLK_I2C_SCL_T | I2C clock (SCL) | LA02_P |
| CLK_I2C_SDA_T | I2C data (SDA) | LA02_N |
The Si5328 has the I2C address 0x68.
| A6 | A5 | A4 | A3 | A2 | A1 | A0 | Hexadecimal |
|---|---|---|---|---|---|---|---|
| 1 | 1 | 0 | 1 | 0 | 0 | 0 | 0x68 |
Refer to the Si5328 datasheet for detailed information on the device registers and how to configure the clock outputs.
QSFP I2C
Note that the I2C addresses of the QSFP/QSFP+/QSFP28 modules are dependent on the specific module used. Refer to the module datasheet for this information. Remember to assert MODSEL_L (drive LOW) before attempting I2C communication with a QSFP28 module.
EEPROM
The 2K EEPROM is intended to store information that identifies the mezzanine card and also specifies the power supplies required by the card. This information is typically read by the system power management on the carrier board when it is powered up. In typical user applications, it should not be necessary to read the data on the EEPROM, and we highly recommend against writing to the EEPROM. Nevertheless, if you wish to access the EEPROM, it can be read and written to at the I2C address 0x50.
| A6 | A5 | A4 | A3 | A2 | A1 | A0 | Hexadecimal |
|---|---|---|---|---|---|---|---|
| 1 | 0 | 1 | 0 | 0 | 0 | 0 | 0x50 |
The EEPROM sits on the FMC card’s dedicated I2C bus. The FMC pins of the EEPROM’s I2C bus are shown below, and it is up to the user to determine their corresponding connections to the FPGA/MPSoC on the carrier board being used.
| I2C bus signal | FMC pin name | FMC pin number |
|---|---|---|
| SCL (clock) | SCL | C30 |
| SDA (data) | SDA | C31 |
Be aware that on some carrier boards, the FMC I2C bus passes through an I2C MUX. On some boards it connects to
FPGA pins whereas on others it connects to PS pins. If you wish to communicate with the EEPROM, it is necessary
to check the schematic drawing of your carrier board to determine the structure of the I2C bus and to which
pins it connects.
Restoring contents
If you need to reprogram the EEPROM with the original factory contents, you can use the Opsero FMC EEPROM Tool.