cyclone III configuration chain problem

[Altera_Forum]

Hi,  

 I have two EP3C25Q240 cyclone III fpgas on my board with the EPCS16 configuration device. The system is set up for multi device AS configuration as per figure 9-4 in the cyclone device handbook.   I do not seem able to get this working and am sure that I am missing a step somewhere.   For an experiment I tied the nCE of the second fpga to VSS and tried to program one file into both fpgas simultaneously. This works and both fpgas have the same code loaded which sort of implies that the connections, power supplies are OK.   Putting nCE of the second FPGA back to normal I tried the following :   1 ) Generate one pof with one design - send to config device - this works as the first fpga gets configured and the second doesn't. Also nCEO of the first fpga goes low after configuration as expected.   2 ) Generate one pof with two sofs ( same sof twice ) by using the "convert programming file" option in Quartus. I select POF as output, EPCS16 as the config device with active serial, create memory map file is ticked by default and under "input files to convert" I have   SOF data Page_0 <auto> fgpatest.sof EP3C25Q240 fgpatest.sof EP3C25Q240   When I have this pof in the config device neither of the fpgas get programmed. I would have thought that at least the first one would still get programmed as it is the same sof file used twice.   Any help and suggestions are welcome as I am completely stuck at present!

[Altera_Forum]

Have you tied nCONFIG, nSTATUS, and CONF_DONE in common? 

 Cheers, Dave

[Altera_Forum]

to do multi fpga configuration, double check the following items: 

- tie 1st fpga's NCEO to 2nd fpga's NCE. - set 2nd fpga's configuration mode to passive serial.

[Altera_Forum]

Hi, 

 Thanks for the replies.   Initially I had both nCONFIG connected together, both nSTATUS connected together and both CONF_DONE connected together. The nCEO of the master device ( pin 162 ) was connected to the nCE ( pin 30 ) of the slave. The master is set up for AS and the slave as PS.    Then when trying to figure out why things were not working I split the signals so I could see each FPGA on its own but they are now back together.    The schematic for the config section should hopefully be attached.   The really strange thing is that even when I am only trying to configure one fpga with a pof which holds two sofs it will not configure. Then using the pof with one sof it will configure. Is there anything I need to know about the convert programming files?   One other item I should point out is that my master is at 3v3 as is the config device but the slave is at 2v6. The DCLK, DATA and nCEO all go through MC74VHC1GT50 level shifters. The pull ups on nSTATUS, nCONFIG and CONF_DONE are 10kOhms to 2V6.   Best regards   Gary

[Altera_Forum]

seems ok from the schematic.  

 when you configure 1 fpga, the pof must only contain 1 sof inside. when you are doing 2 fpga configuration, then the pof must contain 2 sofs inside. the number of devices must tally.

[Altera_Forum]

Hi Gary, 

 Have you tried configuring both devices using JTAG?  Try configuring them both as a two device chain (nCEO->nCE, etc), and if that fails, try configuring them individually.  Perhaps that may provide some insight as to your issue. For example, if both can be configured via JTAG, you know the issue is definitely related to your AS/PS setup. If you cannot get the second device to configure at all, then your problem might not be your configuration logic, but the power supplies on the second FPGA.  Cheers, Dave

[Altera_Forum]

Hi, 

 again - thanks for your input. I now know what the issue was. I believe that U18 was causing too much delay so the enable was not enabled until 1 clock too late and hence it always failed to config. Changing U18 to a direct through path with pull up to 2V6 solved the problem.   Best regards   Gary

[Altera_Forum]

Hi Gary, 

   --- Quote Start ---   I now know what the issue was. I believe that U18 was causing too much delay so the enable was not enabled until 1 clock too late and hence it always failed to config. Changing U18 to a direct through path with pull up to 2V6 solved the problem.   --- Quote End ---    Glad to hear you got things working!   Thanks for taking the time to update the forum with your solution.  Cheers, Dave