Placing a Crosspoint Switch Module

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Modified by Admin on Sep 13, 2017

The configurable Crosspoint Switch module provides an efficient means by which to switch signals in a design. Figure 1 shows a simple example circuit using this instrument.

The circuitry in Figure 1 has been constructed to simplify illustration of how the device works. Inputs to the device are simply generated from a configurable Digital I/O module, and the outputs of the Crosspoint Switch module wired back as inputs to the same Digital I/O device. Typically, the output blocks of the instrument would be connected elsewhere in the design, for FPGA testing/debugging purposes.

Figure 1. Using a Crosspoint Switch module to simplify switching of signals in a design.

In the example circuit above, the Crosspoint Switch module has been configured with two input blocks (AIN, BIN) and three output blocks (AOUT, BOUT, COUT). The common block structure for these inputs and outputs has been defined with the following constituent signals:

Addr[15..0]

Data[15..0]

The generated 16-bit digital signals from the Digital I/O module are fed into the Crosspoint Switch module as follows:

Output signals X_Addr and X_Data are connected to the Addr and Data signals of input block AIN, respectively.

Output signals Y_Addr and Y_Data are connected to the Addr and Data signals of input block BIN, respectively.

The output blocks of the Crosspoint Switch module are connected back as input signals to the Digital I/O module as follows:

Addr and Data signals of output block AOUT are connected to input signals ChannelA_Addr and ChannelA_Data, respectively.

Addr and Data signals of output block BOUT are connected to input signals ChannelB_Addr and ChannelB_Data, respectively.

Addr and Data signals of output block COUT are connected to input signals ChannelC_Addr and ChannelC_Data, respectively.

Remember that when using any virtual instrument in a design, you must ensure that the Soft Devices JTAG chain is enabled. For more information, see Enabling the Soft Devices JTAG Chain.