Accessing the SDPs on the i210

1 Introduction

The Intel i210 Ethernet controller features four programmable pins, known as "Software Defined Pins" or SDP. Two of these pins are routed to a six pin header. With minimal rework, the card becomes a versatile, inexpensive PTP hardware testing solution.

2 Abbreviations

DUT	Device Under Test	PPS	Pulse Per Second
GM	Grand Master	PTP	Precision Time Protocol
GPS	Global Positioning System	SDP	Software Defined Pin
PC	Personal Computer	TC	Transparent Clock

3 Pinout of the Six Pin Header

Figure 1: Intel i210 with rework

The six pin header can be seen in the lower left hand side of Figure 1. Table 1 gives the pinout along with the colors of the wires in the photograph.

Table 1: Six Pin Header
Pin	Signal	Wire Color
1	?	-
2	SDP0	Orange
3	GND	Black
4	SDP1	Green
5	?	-
6	?	-

4 Providing 3.3 Volt Power to a Transceiver

An RS232 transceiver may be used to electrically isolate the PC from the DUT. The device shown in Figure 2 requires power at the same voltage level as the input and output signals.

Figure 2: NulSom RS232 Transceiver

Unfortunately there is no convenient header from which to obtain 3.3 Volt power, and so the rework entails soldering a wire to a capacitor near the voltage regulator, as seen in Figure 1 on the upper right hand side. Figure 3 shows a close up view of the solder spot.

Figure 3: 3.3 Volt Power

5 Application Ideas

5.1 Single i210

PTP device testing

Connect the transceiver to a another transceiver on a DUT that can produce a 1-PPS signal. Configure SDP1 as an input. Use the PPS time stamps on SDP1 to characterize the DUT synchronization performance as a PTP server and as a PTP client.
GPS Grand Master clock

Connect the transceiver to a another transceiver on the PPS output of a GPS radio. Configure SDP1 as an input. Use the PPS time stamps on SDP1 to synchronize the i210 to the GPS time.

5.2 Multiple i210 cards

Figure 4: Test Machine with Three Cards

Two or more reworked i210 cards may be installed into one PC. Figure 4 shows a setup with three cards and a simple adapter to connect their SDP0 pins together directly, without using a transceiver. This only works when the grounds of the PCIe slots are tied together at the same level. Some PC motherboards have multiple PCIe buses with different ground levels! Using multiple cards opens up possibilities for additional test applications.

PTP network equipment testing

This method may be used to measure the synchronization performance of multi-port PTP devices such a Boundary Clocks and Transparent Clocks. Configure SDP0 on the first card as an output and let it generate a PPS output signal. Configure SDP0 on the other cards as inputs. Run a PTP time server on the first card's interface, and run PTP clients on the others.

First, connect the cards to the first card individually, using an Ethernet cable directly. Use the PPS time stamps on the SDP0 input to obtain the base line performance.

Then, connect the cards to the DUT. Use the PPS time stamps on the SDP0 inputs to measure the time error introduced by the DUT.
Transparent Clock

Use the ts2phc-TC.cfg example configuration from linuxptp and let the ts2phc program synchronize the other cards to the first one. Run the ptp4l program in TC mode on all the card's network interfaces.

6 Links

Intel i210

https://smile.amazon.com/Intel-Corp-I210T1BLK-Retail-Unit/dp/B00C49QC20

RS-232 Transceiver