1

12V

2

12V

3

12V

4

Sense1

5

GND

6

Sense0

7

GND

8

GND

GND

GND

PKG_ID1

Input (to BlueField-3)

NC-SI PKG_ID

Shoul be connected to the Primary controller NC-SI PKG_ID pins to set the appropriate package ID.

PKG_ID0 should be connected to the endpoint device GPIO associated with Package ID[0]. PKG_ID1 should be associated with Package ID[1].

Baseboard should connect to GND or leave floating.

DPU should have a 4.7k PU.

RBT_RXD0

Output (from BlueField-3)

Receive data. Data signals from the network controller to the BMC.

For baseboards, this pin should be connected between the baseboard NC-SI over RBT PHY and the connector. This signal requires a 100 kΩ pull down resistor to GND on the baseboard between the BMC and the RBT isolator to prevent the signal from floating when no card is installed.

For DPUs, this pin should be connected between the connector and the RBT PHY.  External termination determined by the DPU RBT PHY requirements.

RBT_REF_CLK

Input

RBT Reference clock. Synchronous clock reference for receive, transmit and control interface. The clock should have a typical frequency of 50MHz ±50 ppm.

For baseboards, this pin should be connected between the baseboard NC-SI over RBT PHY and the DPU  cable connector. The RBT_REF_CLK should not be driven until 3.3V AUX is present on the DPU. The RBT_REF_CLK should be continuous once it has started.

For DPUs, this pin should be connected between the connector and the RBT PHY.  No external termination is required.

RBT_RXD1

Output

Receive data. Data signals from the network controller to the BMC.

For baseboards, this pin should be connected between the baseboard NC-SI over RBT PHY and the connector. This signal requires a 100 kΩ pull down resistor to GND on the baseboard between the BMC and the RBT isolator to prevent the signal from floating when no card is installed.

For DPUs, this pin should be connected between the connector and the RBT PHY.  External termination determined by the DPU RBT PHY requirements.

GND

GND

RBT_CRS_DV

Output

Carrier sense/receive data valid. This signal is used to indicate to the baseboard that the carrier sense/receive data is valid.

For baseboards, this pin should be connected between the baseboard NC-SI over RBT PHY and the connector. This signal requires a 100 kΩ pull down resistor on the baseboard between the BMC and the RBT isolator to prevent the signal from floating when no DPU is installed.

For DPUs, this pin should be connected between the connector and the RBT PHY.  External termination determined by the DPU RBT PHY requirements.

RBT_ISOLATE_N

Output

This signal is used to indicate the DPU has powered and is ready for NC-SI physical layer connection to be present.  When low the baseboard circuitry will isolate the NC-SI connection to the DPU.  When high normal NC-SI RBT connectivity is available.

Baseboards should terminate this with a 47K-100K PD resistor.

DPUs should terminate with a 10k PU resistor.

GND

GND

PKG_ID0

Input

NC-SI PKG_ID

should be connected to the Primary controller NC-SI PKG_ID pins to set the appropriate package ID.

PKG_ID0 should be connected to the endpoint device GPIO associated with Package ID[0]. PKG_ID1 should be associated with Package ID[1].

Baseboard should connect to GND or leave floating.

DPU should have a 4.7k PU.

RBT_TX_EN

Input

Transmit enable.

For baseboards, this pin should be connected between the baseboard NC-SI over RBT PHY and the connector. This signal requires a 100 kΩ pull down resistor to ground on the baseboard between the RBT isolator and the DPU cable connector to prevent the card-side signals from floating when the RBT signals are isolated. 

For DPUs, this pin should be connected between the connector and the RBT PHY.  External termination determined by the DPU RBT PHY requirements.

GND

GND

RBT_TXD0

Input

Transmit data. Data signals from the BMC to the network controller.

For baseboards, this pin should be connected between the baseboard NC-SI over RBT PHY and the connector. This signal requires a 100 kΩ pull down resistor to GND on the baseboard between the RBT isolator and the DPU cable connector to prevent the card-side signals from floating when the RBT signals are isolated.

For DPUs, this pin should be connected between the connector and the RBT PHY.  External termination determined by the DPU RBT PHY requirements.

UART_TX

Input

3.3V UART TX signal from the baseboard

RBT_TXD1

Input

Transmit data. Data signals from the BMC to the network controller.

For baseboards, this pin should be connected between the baseboard NC-SI over RBT PHY and the connector. This signal requires a 100 kΩ pull down resistor to GND on the baseboard between the RBT isolator and the DPU cable connector to prevent the card-side signals from floating when the RBT signals are isolated.

For DPUs, this pin should be connected between the connector and the RBT PHY.  External termination determined by the DPU RBT PHY requirements.

UART_RX

Output

3.3V UART RX signal to the baseboard

PRESENCE_N

Presence of DPU. Baseboard should implement a 200 Ω series resistor and 4.7kohm pull-up resistor to 3.3V AUX.

DPU should tie this to GND.

GND

GND

RBT_ARB_OUT

Input

NC-SI hardware arbitration output.

If the baseboard supports multiple DPUs cards connected to the same RBT interface, it should implement logic that connects the RBT_ARB_OUT pin of the first populated DPU card to its RBT_ARB_IN pin if it is the only card present or to the RBT_ARB_IN pin of the next populated card and so on sequentially for all cards on the specified RBT bus to ensure the arbitration ring is complete. This logic should bypass slots that are not populated or powered off.

RBT_ARB_IN

Output

NC-SI hardware arbitration input.

If the baseboard supports multiple DPUs cards connected to the same RBT interface, it should implement logic that connects the RBT_ARB_IN pin of the first populated  DPU card to its RBT_ARB_OUT pin if it is the only card present or to the RBT_ARB_OUT pin of the next populated card and so on sequentially for all cards on the specified RBT bus to ensure the arbitration ring is complete. This logic should bypass slots that are not populated or powered off.