Keywords： Multiplexer/Switch  Transparent Communications

基本特征：

DS26900是一款JTAG信號復用器，能夠將3路主機端口之一連接到18路(36路級聯(lián)配置)次級端口。該器件可以通過三個主機端口中的任意一路進行配置。DS26900可自動檢測次級端口JTAG器件的連接狀態(tài)。

方案特點：

Ribbon Cable Connectors for Master and
Secondary JTAG Port Connections
Jumpers for Device Configuration
LEDs for Device State Outputs
Simple Power Connections

The simplest configuration to test for communication with the DS26900 demo kit is to connect a JTAG source to master port 1, connect power, and, using JTAG sequences, manipulate some of the device state output LEDs on the board. The SSPIx LEDs can be used to verify that the desired secondary port is being selected. The GPIOx LEDs can be observed to verify that the GPIO pins are being correctly selected.

Some signals available at these

connectors can be controlled dynamically from the connector or from jumpers.
When driving a signal from the master port connectors the jumper can be removed or
placed in a pullup or pulldown position determined by the method of driving the signal.

參考原理圖：



原理圖1



原理圖2




原理圖3