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.
| 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 |
The six pin header can be seen in the lower left hand side of Figure fig:rework. Table tab:pinout gives the pinout along with the colors of the wires in the photograph.
| Pin | Signal | Wire Color |
| 1 | ? | - |
| 2 | SDP0 | Orange |
| 3 | GND | Black |
| 4 | SDP1 | Green |
| 5 | ? | - |
| 6 | ? | - |
An RS232 transceiver may be used to electrically isolate the PC from the DUT. The device shown in Figure fig:rs232 requires power at the same voltage level as the input and output signals.
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 fig:rework on the upper right hand side. Figure fig:closeup shows a close up view of the solder spot.
- 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.
Two or more reworked i210 cards may be installed into one PC. Figure fig:threecards 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.cfgexample configuration from linuxptp and let thets2phcprogram synchronize the other cards to the first one. Run theptp4lprogram in TC mode on all the card’s network interfaces.
Intel i210
RS-232 Transceiver