Intel® Quartus® Prime Software
Intel® Quartus® Prime Design Software, Design Entry, Synthesis, Simulation, Verification, Timing Analysis, System Design (Platform Designer, formerly Qsys)
Announcements
Intel Support hours are Monday-Fridays, 8am-5pm PST, except Holidays. Thanks to our community members who provide support during our down time or before we get to your questions. We appreciate you!

Need Forum Guidance? Click here
Search our FPGA Knowledge Articles here.
14950 Discussions

Is it possible to force all I/O HighZ before programming (CPLD Max_V)

JTixi
Beginner
615 Views

On our circuit board, the TDO line as been linked through another I/O pin which is not used in the project (BGA 100 package). The ​first programmation was good. However the unused I/O are linked to ground (why is it the default configuration in Quartus assignment?). It is no more possible to programm the device again, as the TDO is now connected to GND. It seems possible to place all I/O in HighZ mode using the JTAG chain debugger and instruction 0x0B. But this is not kept for further instruction. Do you have an idea or I place the board in rubish box ? Or is it possible to send program file without TDO checking ? Thank you in advance.

0 Kudos
3 Replies
YuanLi_S_Intel
Employee
76 Views
Hi Jean, By right the I/O pin are tri-stated with weak pull-up before configuration, i dont see any problem here. If you would like to program the device again after it is in user mode, you may change the state of the unused pin. To do so, go to Quartus -> Device -> Unused Pin -> Input pin as tri-stated with weak pull up. YL
JTixi
Beginner
76 Views

​Hello!

I thank you for your reply. I think however that the JTAG chain is checked at beginning of normal programmation process, without tri-stating the I/O.  It is the raison why I allways get an error (Device not connected). Is there any method to force tri-state on I/O before programming or skip JTAG test, using a script on console for example ?

JMT.

YuanLi_S_Intel
Employee
76 Views
Aplogize that TDO check cannot be disabled and all the JTAG pin (TDO) cannot be used as normal IO pin. https://www.intel.com/content/dam/www/programmable/us/en/pdfs/literature/hb/max-v/max5_handbook.pdf (Page 43) Even if it is unused, you will need to leave it unconnected as per pin connection guidelines. https://www.intel.com/content/dam/www/programmable/us/en/pdfs/literature/dp/max-v/pcg-01012.pdf Regards, YL
Reply