Cost-Effective Energy Monitoring of a Zynq-Based Real-Time System Including Dual Gigabit Ethernet

Abstract

Recent FPGA architectures integrate various power management features already established in CPU-driven SoCs to reach more energy-sensitive application domains such as, e.g., automotive and robotics. This also qualifies hybrid Programmable SoCs (pSoCs) that combine fixed-function SoCs with configurable FPGA fabric for heterogeneous Real-time Systems (RTSs), which operate under predefined latency and power constraints in safety-critical environments. Their complex application-specific computation and communication (incl. I/O) architectures result in highly varying power consumption, which requires precise voltage and current sensing on all relevant supply rails to enable dependable evaluation of available and novel power management techniques. In this paper, we propose a low-cost 18-channel 16-bit-resolution measurement system capable of over 200 kSPS (kilo-samples per second) for instrumentation of current pSoC development boards. In addition, we propose to include crucial I/O components such as Ethernet PHYs into the power monitoring to gain a holistic view on the RTS's temporal behavior covering not only computation on FPGA and CPUs, but also communication in terms of, e.g., reception of sensor values and transmission of actuation signals. We present an FMC-sized implementation of our measurement system combined with two Gigabit Ethernet PHYs and one HDMI input. Paired with Xilinx' ZC702 development board, we are able to synchronously acquire power traces of a Zynq pSoC and the two PHYs precise enough to identify individual Ethernet frames.