I tried uploading a bitstream to my IceCore using "cp chip.bin /dev/ttyACM1". Usually this process exits within a couple seconds, and the bitstream begins executing. This time, however, instead of exiting, the green S light began blinking, along with the red D light remaining lit, and the "cp" process just hanged there. The FPGA "program" never began "executing".
This was just after I had tested a change to the "blink" example, changing the LED output pin to 32 in chip.pcf. I decided to try what I was going to test with the vanilla example, so I did "make clean", "git reset --hard", and rebuilt chip.bin. However, when I tried to flash it, I still got the same problem. Same with the "trail" example, also unmodified. This persisted after disconnecting and reconnecting the board multiple times, and even unloading the "cdc_acm" kernel module (which was reloaded automatically when I plugged it back in.)
I decided to reflash IceBoot, thinking maybe something somehow got corrupted in the firmware. But now I don't even get the serial port; I connect the USB cable to the "PRG" port and all four status LED's go on (M, S, D, and P) but no device is detected on my PC, as if I had connected it to the other ("COM") USB port.
DFU mode still works, thankfully, so my device isn't bricked, if only I can get the firmware to flash properly. But my questions are:
1) What else should I try to get IceBoot working again?
2) What does the blinking S light mean? Or better yet, where should I look for the answers to questions like this? I haven't seen much in the way of official documentation.
3) If reflashing IceBoot doesn't fix my original issue, what should I try next?
Thanks for your help.