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Active serial configuration and programming does not work

Honored Contributor I

Cyclone 3 device with EPCS16 device connected. 

Board looks like dead, connecting AS cable and using USB blaster gives error "can't recognize silicon ID". 

Tools we have: multimeter only, unfortunately. Board was working before (I tested it), when it arrived to the field it did not start. Packing was done properly, thus no physical damage should occur. 


We measured AS programming connector after power up (and unsuccessful FPGA configuration), and 

- CONF_DONE = low 

- NCONFIG = high 

- DATA = high 

- ASDI = low 

- NCE = low (no shortage to ground) 

- NCS = high 


Also measured NSTATUS, and it is low. 


Correct power levels are there (1.2 V, 2.5 V and 3.3 V). I used circuit with diodes and capacitors as advised for in-circuit AS programming. 


My understanding: 

- nconfig triggered configuration, but it did not finish for some reason (conf_done low, n_status low); 

- USB blaster can not hijack EPCS device. 


I have two questions - 

- where should we look into to get progress in troubleshooting? 

- what could be the cause? 


PS. There was similar thread (, but I did not follow it up because board is in the field and there was no opportunity to do so. There also was another thread ( about device not configuring, but when this pad is not soldered, programmer is able to hijack the EPCS and program it, but Cyclone does not configure. In current situation both do not work. 


edit: tried shorting nCONFIG manually to the ground using wire - no result. 


update: checked with logic probe, after device power up: 

DCLK pulses 


nCONFIG high 

dataout high 

ASDI pulses 

nCE low 

nCS pulses 


Seems FPGA tries to continuously get something from the chip in the loop, and can not stop.
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