2.5.36. TAPOp_SetAutoBypassInstruction

Defines the instruction that is loaded into the IR when the server switches to another connection.


#include “tapop.h”

extern TAPOp_ErrorTAPOp_SetAutoBypassInstruction (unsigned8 connectId, unsigned32 auto_bypass);



Connection ID, as returned by TAPOp_OpenConnection.


Instruction pattern to use when the device is auto-bypassed by the server.



No error.


In a multi-device system, when the Multi-ICE server accesses a specific device, it automatically loads an instruction into the IR registers of the other devices. The default instruction it uses is the BYPASS instruction defined in the IEEE 1149.1 standard:

  • This scheme works for multiple debugger connections where the debugger uses INTEST to change the internal state of the device.

  • When EXTEST is being used to apply test vectors to the pins of the device, switching connections to another device causes BYPASS to be loaded. This affects the state of the external device pins.

    To get round this, some devices have a CLAMP instruction that latches the state of the pins when the device is in EXTEST mode.

You can use this function to define the instruction that is loaded into the IR when the Multi-ICE server switches to another connection. For example, instead of the default BYPASS instruction, you might load the CLAMP instruction for the device.

The selection status of the connection is irrelevant (this call cannot return TAPOp_UnableToSelect), and the selection status is not modified by this call.


This function first appeared in Multi-ICE Version 1.4.

See also

This TAPOp API function provides similar or related functionality:

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