SD Specifications Part 1 UHS-II Simplified Addendum - SD Association

UHS-II Simplified Addendum Version 1.01©Copyright 2010-2013 SD Card Association3.1.2.1 Ring ConnectionFigure 3-5 illustrates an example of Ring connection. Connection rule of data Lanes is as follows.(Note that 2L-HD mode is not available in Ring connection in UHS-II Addendum Version 1.00.)HostTxRxRxTxRxTxRxTxRxTxDevice#1Device#2Device#3Device#NFigure 3-5 : Example of Ring Connection(1) D0.Tx of Host is connected to D0.Rx of Device#1(2) D1.Tx of Device#1 is connected to D0.Rx of Device#2, and this operation is repeated.(3) D1.Tx of Device#N (final Device) is connected to D1.Rx of Host, and Ring connection completes.Examples of RCLK distribution method are illustrated in Figure 3-6.(a)(b)RCLK#4 TxRCLK#3 TxRCLK#2 TxRCLK#1 TxRCLKTxTerninated externally orat the final receiverRTRx Rx Rx RxRx Rx Rx RxHostTxD0RxD1RxD0TxD1Device#1RxD0TxD1Device#2RxD0TxD1Device#3RxD0TxD1Device#4HostTxD0RxD1RxD0TxD1Device#1RxD0TxD1Device#2RxD0TxD1Device#3RxD0TxD1Device#4Figure 3-6 : Examples of RCLK distribution method for RingFigure 3-6 (a) shows a multiple point to point method which uses a separate RCLK driver (RCLK.Tx) foreach Device. With this method, Host needs to have at least the same number of RCLK.Tx Ports as thenumber of connecting Devices. If Host has only one RCLK.Tx Port, multi-drop method can be applied toconnect multiple Devices (Figure 3-6 (b)). With this method, RCLK bus is terminated externally or at thefinal receiver. In addition this method requires careful signal integrity design.Note that Device has only one RCLK.Rx Port even in the case of Figure 3-6 (b).3.1.2.2 Hub ConnectionFigure 3-7 illustrates an example of Hub connection.Hub shall have one Device PHY for Host connection and plural number of Host PHYs for Deviceconnection. Hub also has functions such as transmitting signals to all connected Devicessimultaneously, or selecting a packet destination according to its content.6