JTAG Question

[sjo]

Posted on April 02, 2004 at 14:32

JTAG Question

[sjo]

Posted on May 17, 2011 at 11:58

I have noticed that on newer versions of PSDExpress it does not allow the JTAG pins to be changed, ie. they are deicated for JTAG. And this is also stated in the datasheet.

Really my question is has this functionality been removed just by PSDExpress or is JTAG multiplexing not supported by the UPSD itself. I also notice that the jtagsel node can still be addressed in the abel file, can the JTAG bit used in the CSIOP space, or is it read-only ? Is the uPSD PSD based on the PSD81* family because I notice the mention of this device in the PSDExpress files? This range supported JTAG multiplexing. It is a shame if it has been removed because sometimes it was a handy feature of the older PSD devices where pincount becomes a problem. Regards sjo

[joseph2399]

Posted on May 17, 2011 at 11:58

The reason for uPSD no longer support multiplexing the JTAG port is because in this mode of operation, the JTAG port can sometimes be disabled by accident when this happens you have to throw away the part since it can not be recovered by a parallel programmer like the regular PSDs do. The JTAG multiplexing functionality is still there, however PSDsoft Express won't allow you to configure these pins to anything other the JTAG function.

[sjo]

Posted on May 17, 2011 at 11:58

If the JTAG multiplexing is still supported by the silicon, why has the option been removed?

Surely this is a per user decision - if the device is configured wrong then this is the developer's fault not ST's. The ability to JTAG multiplex is a device plus point, not something to hide. I also have an older version of PSDExpress (7.6) which does allow JTAG multiplexing, is it enabled the same as the PSD8x series, ie. 1. Delete dedicated JTAG in PSDExpress 2. Define CPLD input, eg. jen on PC7 and set equation jtagsel = !jen JTAG can then be enabled by either software setting JTAG_ENABLE bit in csiop or external low signal on PC7. I am sure many other developers would find this feature an advantage if it was re-enabled in future. Many Thanks sjo

[sjo]

Posted on May 17, 2011 at 11:58

Its ok I just tried it and it works ok.

Regards sjo

[gj2]

Posted on May 17, 2011 at 11:58

Can anyone point me to the older version of PSDSoft Express (ver 7.6) as mentioned above??

Many thanks.

[sjo]

Posted on May 17, 2011 at 11:58

Carrying on from above comments on jtag multiplexing - is there any chance in the future the option will be re-enabled.

Otherwise myself and other developers will find themselves having to use older versions of the software - which is not a good thing. Can this not be implemented under an advanced option ? Regards sjo

[sjo]

Posted on May 17, 2011 at 11:58

Moderators, anyone @ PSDSupport.

Regards sjo

[joseph2399]

Posted on May 17, 2011 at 11:58

After much consideration some time ago, it was decided that the JTAG pins would be dedicated and not selectable as in the past. Future versions of PSDsoft will not re-enable this feature.

[sjo]

Posted on May 17, 2011 at 11:58

Thanks for your reply, but why then do you not do the same for the other PSD devices, eg. PSD8XX range.

Whats the difference ? Regards sjo