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RM42L432: RM42L432 JTAG connection to JLink ...

Part Number: RM42L432


we use a J-Link debugger in conjunction with the RM42L432 controller on our board.

The J-Link cannot connect. I think I found the problem but would like to confirm.

In our hardware connection to the JTAG, we have the signal RTCK not connected. Is this the problem?

Here is JTAG connection as schematic:

Thank you!

  • Hello Frank,

    RTCK is not a standard JTAG signal. The asynchronous TAP controller does not require local synchronization, so the RTCK is not a MSUT. 

    But, occasionally a target device requires the JTAG interface to be externally synchronized to a clock within the device due to it being slow, non-continuous, or variable. The adaptive clocking feature uses the RTCK to address this requirement. When adaptive clocking is enabled, the debug unit issues a TCK signal and waits for the RTCK signal to return before sampling TDO.

    If you emulator supports adaptive clock feature, and you are planning to use this feature, you need RTCK from the target device. 

    Please check nTRST which should be pulled down.

  • Hi QJ Wang,

    thank you for your help!

    Sincerely - Frank