Question about scan insertion in DC

[rogger123]

Scan insertion

Hi
would DC flag an error if i were to use an output port of the chip as the scan data in port during scan insertion.. or would DC automatically add a bidirectional buffer which would be controlled by scan enable?
or is there a specific constraint which needs to be added so that DC could add the buffer itself.

rgds
rogger

 

[atremp]

Scan insertion

By default, DFTC minimizes the number of dedicated test ports by sharing outputs with functional ports. By default, DFTC always generates a dedicated scan input port. If you select a bidirectional port as the scan input port, DFTC automatically inserts the necessary bidirectional control logic. The scan-enable signal is the control signal.

 

[rogger123]

Re: Scan insertion

hi,
the port i have selected is an output port not a bidirectional port...
will DC still add the necessary logic using scan enable as control?
rgds
rogger

 

[atremp]

Scan insertion

Why you choose a output port for scan in port, I think it is necessary to modify the output port to bidirectional port by adding the output enable control signal, BTW: in test mode shift process, DFT compile automatically set all bidirectional ports to be input direction.

 

[rogger123]

Re: Scan insertion

hi,
does that mean if i just change the port type to "inout" instead of "output" it should solve the problem??
will DFTC then add the buffer logic to make the port as an input type during scan and an output type during normal operation?

rgds
rogger

 

[atremp]

Scan insertion

you can modify the output port or select another (maybe dedicated ) port for scan in,
for detailed information about this, pls man "set_scan_configuration " in DFT compile and search "bidi_mode input " option

 

[flysnake]

Scan insertion

if bidirectional port be used as scan out port, when scan enable is zero(capture), the port direction is input or output?