Using JTAG on MAX10: SHIFT_IR reads 0x151 instead of 0x155. What does it mean?

[MSchu50]

We are using the JTAG interface on MAX10 and in general this works as expected.

https://www.intel.com/content/www/us/en/programmable/documentation/sss1396244916395.html#sss1396246786298 states that the content of the Instruction Register is a 1010101010 pattern (0x155), and we should check it. Usually this is true.

Sometimes we get 1000101010 (0x151) as previous IR content, just one bit flipped. It is always the same one, and it is visible on the line.

The issue seems to be bound to hardware. Some HW shows it repeatedly, some never.

If we ignore this bit, everything still works as expected. So contrary to what the linked document states, the device seems to have well reached the proper state.

So I would like to ask: What is the meaning of this bit? Does the MAX10 try to tell us something we should care about?

[YuanLi_S_Intel · Accepted solution]

Hi Markus,

Sorry for being late, as i was checking with the team about this. Regarding to the diff pattern that you saw, as long as it starts with "10..", it shouldnt be any problem on it.

Thank You.

[MSchu50]

Hi YL, thank you for checking with the team and your response! Regards Markus