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.
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 ?