Issue link: https://resources.mouser.com/i/1512203
28 ADI | Engineering a More Sustainable Future X Simplified wiring, requiring only a single twisted pair. The possibility to also deliver power on the data line allows low power devices, such as sensors, to be directly powered from this connection, further reducing the number of required wiring and connectors, and so lowering the complexity, cost, and weight of the overall system. X Power delivery using the PoDL standard, which uses a DC voltage superimposed on data lines to supply power to devices connected to the network. This type of coupling can be achieved by only using passive components, and once the voltage on the receiver end is filtered, it can be directly used to power the device or a DC-to-DC converter without requiring rectification. By correctly dimensioning components used for this type of coupling, a high efficiency system can be achieved. In this project, using standard components installed on the evaluation boards leads to an overall efficiency of about 93% (with a 24 V supply and total load current of 200 mA). However, this result has a wide margin for improvement—indeed, most of the losses are due to resistive drops of the passive components along the power path. X Versatility, as it can be used for both last-mile and end-point connectivity. Analog Devices 10BASE-T1L devices have been tested for distances up to 1.7 km. They also allow daisy-chaining with a low impact on system complexity. For example, by using the ADIN2111 two-port low complexity switch, it is possible to design devices that integrate daisy-chaining capabilities, making the link suitable also for end-point nets. X Easy to interface with existing equipment that already integrates an Ethernet controller, including personal computers and laptops. Data frames follow the Ethernet data link standard, and all Ethernet-compatible protocols can be implemented above it, so only a media converter is needed as a bridge with standard Ethernet links. For example, the board used in this project, the EVAL-ADIN1100, can be used as a reference design for a transparent media converter, requiring only two Ethernet PHYs and an optional microcontroller for configuration and debugging. X High data rate, reaching up to 10 Mbps, full duplex. This, combined with the daisy-chain topology on which industrial Ethernet-based protocols can be implemented, allows it to be used in a real-time application, where deterministic transmission latency is required. X Isolation between the transceiver and media can be achieved with both capacitive or magnetic coupling, depending on the safety and robustness requirements of the application. Multiple measurements were done on the system to evaluate its performance. All the peripherals used to communicate with the ADIN1110 transceiver and TMC5160 controllers were configured for the maximum possible speed that is reachable with the standard hardware configuration. Considering the 80 MHz system clock of the microcontroller, the data rate of SPI peripherals was set to 2.5 MHz for the motion controllers and to 20 MHz for the ADIN1110 transceiver. For the TMC5160, by tuning the microcontroller clock configuration and supplying an external clock signal to the IC, SPI frequency can be further increased up to 8 MHz, while for the ADIN1110 the maximum limit by data sheet is 25 MHz. For the latency, the total time between a data request and the reception of the answer frame has been evaluated at about 4 ms (average on 500 samples, measured with the Wireshark protocol analyzer computing the difference between the timestamps of data requests and corresponding answers). Additional evaluations were made to determine which parts of the system are responsible for this delay. Results showed that the main cause is the delay function provided by the RTOS, which allows a minimum delay of 1 ms, used to set the interval between write and read operations for the TMC5160, while the required delay is in the order of tens of nanoseconds. This could be improved by defining a different timer-based delay function that allows for shorter delay intervals. The second cause of this delay is the Scapy function used to receive frames, which requires a minimum set-up time of 3 ms after it has been called. In a real-world application, this can be improved by developing the interface directly with network adapter drivers for the operating system, instead of third-party tools like Scapy. However, drawbacks include losing compatibility with different operating systems and increasing code complexity. Precise execution times for the callback implemented on the microcontroller were measured by toggling a GPIO and measuring the high period with an oscilloscope. Measured execution time includes functions used to read and parse received frames and to send commands to motion controllers. Figure 5: A simplified scheme of power path. 5