I have a custom board and the TerasicBlaster (USB Blaster Clone) and at least some communication seems to start OK (reports Device 1 silicon ID is 0x15). I can Erase and Blank Check successfully most of the time (have had a few errors). But when I program and verify it goes through what appears to be the programming process for maybe 15-30 seconds, and then says Can't verify device 1 immediately after trying to starting verification. I'm totally new to this FPGA stuff, and any pointers would be much appreciated! Thanks! -JNS.

I expererienced similar behaviour with USB Blaster and a 0.5 m long IDC flat cable that worked correct for JTAG programming. With a regular short cable, AS programming proceeded normally. You are probably using the Terasic USB Blaster with it's original cable, so you have no option to further improve AS signal quality. You can see however from my experience, that AS programming interface is rather sensitive to signal quality issues, more than JTAG. With Cyclone III, Altera published a suggestion to connect a small capacitor (around 10 pF) at DCLK which apparently improved the situation. Also a small series resistor at DCLK (50 - 100 ohms) may help. I assume, that AS programming connector and EPCS are located near to FPGA and have state-of-the-art wiring, otherwise, the problem could be related mainly to your design. It could be, that although verify fails, the device is programmed correct. If you have also a JTAG interface at the FPGA, you can program the AS device through serial flash loader (SFL) alternatively. SFL works with all FPGAs that also support SignalTap. See the respective application note how to use SFL.

Thanks for the ideas. I have 10pF on DCLK, but I'll try some different values and experiment with the series R. How involved is the FPGA in the process during the programming of the configuration device? Is it being programmed simultaneously and signaling back to the usbblaster. Is the Usbblaster trying to verify from the epcs chip or the fpga? Off to do some experimentation. Thanks, -JNS.

The FPGA isn't involved in AS programming, the FPGA AS interface is disabled by the USB Blaster or another programmer, as it pulls up the nCE line. AS Programming would be possible without a FPGA assembled to circuit. But the FPGA can also program AS memory through the interface, this is utilized with said serial flash loader.

--- Quote Start --- The FPGA isn't involved in AS programming, the FPGA AS interface is disabled by the USB Blaster or another programmer, as it pulls up the nCE line. AS Programming would be possible without a FPGA assembled to circuit. But the FPGA can also program AS memory through the interface, this is utilized with said serial flash loader. --- Quote End --- Just to be sure, is this true for the whole program + verify cycle? What I'm thinking here is that if it is, then I need to focus on the Rs and Cs between the AS connector and the EPCS for now, get that working, and only then concern myself with the connections between the EPCS and the FPGAs? I have jumpers installed between the EPCS and the FPGAs, so I could even take them completely out of the picture for now if that might help (Right now I only have one FPGA installed on the board BTW). Thanks! -JNS.

Another question. Should the silicon ID be 0x14 or 0x15? I get both at different times, and it would be helpful to know which is correct, if either, but I'm not finding any authoritative info online. Thanks, -JNS.

EPCS16 AS Can't Verify Device (General AS Programming Issues)

13 Replies

Altera_Forum
Honored Contributor
18 years ago
I don't know what's happening with your circuit. A strange thing is nCONFIG being permanently low, cause it's an input to the FPGAs. However, if it's low, no FPGA can start configuration. I would try to clarify this first. Also I would not start desolderig parts before all other options have exhausted.

Good luck!
Altera_Forum
Honored Contributor
18 years ago
Thanks for the reply. I'm trying again on my 2nd board just to see if anything becomes apparent. I had a little difficulty soldering the FPGA because while I'm used to soldering QFPs these leads seemed more delicate than I'm used to. Things seem to be going better soldering it this time around. I also built the EPCS circuit first, since I know now it can be programmed on its own at it worked first time.

Have my fingers crossed - will keep you posted.

-JNS.
Altera_Forum
Honored Contributor
18 years ago
Ok, I haven't had a chance to investigate the why, but my second board works, at least with the first FPGA. In another thread before getting the boards fabbed I was in a discussion also about whether or not my design would work with 128 simultaneous channels of 1MHz PWM, and that seems to be fine. I still have a lot of hurdles to jump before getting this thing finished up, but this is a huge start.

Thanks for all your help, and I'll be back posting more progress (and probably questions) as I keep moving forward.

-JNS.

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EPCS16 AS Can't Verify Device (General AS Programming Issues)

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