BUILT- IN TEST 
 
 
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ordering of the signals in the scan chain is defined in the BSDL file that is included in 
the Total-AceXtreme® Development Kit. 
Table 2.  Supported JTAG Functions 
JTAG Instruction  Instruction 
Register 
Value 
Description 
BYPASS  0b111  The BYPASS Instruction is used to allow data to connect directly from 
JTAG_TDI pin to the JTAG_TDO pin. 
Reserved  0b110  Reserved 
Reserved  0b101  Reserved 
USERCODE  0b100  The USERCODE specifies which version of the Total-AceXtreme is present.   
 
0x000000FF denotes the BU-67301B0T0L-E02  
 
Other values are reserved.   
IDCODE  0b011  The IDCODE for the Total-AceXtreme is 0x0590003F 
HIGHZ  0b010  Sets all the Outputs and Bidirectional Outputs to a high impedance state.  The 
HIGHZ can be used to determine excessive leakage current during the Total-
AceXtreme’s manufacturing phase. 
SAMPLE/PRELOAD  0b001  The SAMPLE function provides the ability to capture the current state of the I/O 
pins.  The Preload allows for JTAG to preload the JTAG cells with values which 
will not actually be loaded until the appropriate instruction (such as EXTEST) is 
entered. 
EXTEST  0b000  The EXTEST Instruction allows for a test vector to be applied from the 
Boundary Scan Register to the external pins of the Total-AceXtreme. 
Please contact DDC for further information on using the Boundary Scan feature.