CONF_DONE pin failed to go high problem
Hello
I am using EP4CGX150CF23C8N FPGA. Configuration is done in AS mode from EPCQ128ASI16N flash. All I/O banks are 3.3V. FPGA initial programming done through JTAG with Terasic USB blaster. Attached schematics with relevant connections.
My design is produced already - few hundred boards without any special issues.
Last week I started to design new Logic and Nios (in FPGA) versions and encountered phenomenon in 2 consecutive boards I tested.
In first board I programmed a jic file and it was working but suddenly it looks as it lost a configuration and board stacked (I am blinking few leds connected to FPGA and some of them also from Nios - and all leds just disappeared). Reburn with known released jic solved the issue. After burning of new jic again after few minutes of working - board stacked again. This phenomenon continued several times until it stacked without a recovery option. All tries to reburn the board with any image caused to failure of CONF_DONE.
As I thought that I have an issue only with this single board I tried another new board.
Programming of this board with new jic succeeded and it worked. When I changed slightly again internal image and tried to burn with updated jic - it immediately failed on CONF_DONE error. And also as the first board from this failure it is impossible to reburn it with any jic - it always fail on CONF_DONE.
As I have a remote update option I tried to burn the FPGA image (logic configuration + Nios firmware) on a third board through serial port to flash. It always success without any problems. These .flash files should have the same content as JTAG's jic file. This third board (where I not tried to burn jic file) is working.
In 2 failed boards I tried also to download only sof file (in order to eliminate effects of flash) - but without success (same CONF_DONE) error.
Voltages in both boards were correct.
Tried to reburn failed boards in another PC's (even with stand-alone programmer), another USB blaster and another power supply without success.
My questions:
1. Can it be that all this caused by jic files?
2. You think that maybe the issues I have are because of defected initial burning equipment like USB blaster or momentary problems in power supply that damaged 2 FPGA's?
3. You think that I can ignore these phenomenon based on fact that I have few hundreds of working boards (even they burned only once from JTAG, while all updates if were needed were done from serial port with .flash files) or I must dig in my design in searching design issues?
Thank you