trabucayre
JTAG Device ID code version field is required for some lattice parts
Hi, really like the work done by everyone for this project, it's so useful and a massive benefit to the open ecosystem!
I was working to write to a LCMXO2-2000HC through JTAG and found that although the chip was not recorded in the parts list it was instead recognised as a LCMX03LF-1300C.
As noted here IEEE 1149.1 dictates the upper nibble should specify version, however maybe lattice decided to ignore this as the Lattice LCMXO2-2000HC has the id code: 0x012BB043while the Lattice LCMX03LF-1300C has id code: 0xE12BB043.
As such when the id code upper nibble is masked during the part lookup process an LCMXO2-2000HC will be mistakenly identified as a LCMX03LF-1300C.
As a workaround i just commented out the LCMX03LF-1300C entry and added an LCMXO2-2000HC entry in part.hpp and the loading was successful (ﾉ◕ヮ◕)ﾉ*.✧.
I'm unsure on the best way to proceed with this but maybe part entries could have a way to mark if the version field is required or ignore it and fallback if multiple matching entries are found 🤔, thoughts?
Thanks for your feedback and encouragement ! Yes some devices must have this nibble unmasked to avoid this type of issue. The algorithm seems a bit too much naive and must improved:
- first thing is to re-add the nibble for all LCMX03LF to have distinction between devices
- second thing seems to searchs for devices by using masked and unmasked version. If both are found -> select correct one.
I'm not really happy by the second point: maybe switching search masked and not masked. Have to try...
Thank you for the response!
That makes sense, I can have a look at doing this and raise a PR, if it would be helpful?
Yes of course! Since you have hardware it's maybe useful/easy to validated algorithm update. Thanks!