SD UHS Protocol Support

SD UHS (Ultra High Speed) encompasses the UHS-I and UHS-II interface specifications for SD memory cards, offering significantly faster data transfer rates than legacy SD modes. UHS-I operates on the standard SD interface with a single row of pins, supporting SDR50 (50 MB/s), SDR104 (104 MB/s), and DDR50 (50 MB/s DDR) transfer modes at 1.8V signaling. UHS-II adds a second row of pins to the SD connector, providing two additional differential lanes (D0 and D1) for full-duplex communication at up to 312 MB/s per lane. The SD protocol uses a command-response architecture with CMD and DAT lines, where the host sends commands on the CMD line and the card responds, followed by data transfers on 1 or 4 DAT lines. SD UHS interfaces are found in cameras, drones, single-board computers, automotive dashcams, medical imaging devices, and any application requiring high-speed removable storage. Protocol analysis for SD UHS is critical because the high-speed signaling, voltage switching (from 3.3V to 1.8V), and complex initialization sequences create numerous opportunities for compatibility and performance issues. Engineers need to verify the initialization handshake, speed mode negotiation, command-response timing, and sustained data throughput to ensure reliable card operation across different manufacturers and speed classes.