GREAT NEWS!
I've got it running at 300MHz and it's much more reliable than at lower speeds. I now have 2 chips doing 600 MH/s total with fairly long periods with zero HW errors.
I tried several capacitor values for result capture and the 30pF works well up to about 360MHz. At 380MHz it's lost sync. I tried a brief run at 360 MHz and it worked ok. I need to get a fan working before I run extended tests at higher clocks.
I had to fiddle a lot with the work unit cycle timing. Seems I don't know what's going on because calculated times weren't right. By trial and error I adjusted it to get very few duplicates. I've also implemented code to only update clock cfg when it changes, not every work unit. But I haven't altered the result capture code yet - so even with no extra schmitt buffers and slow result code it's actually doing ok. At 300 MHz the result data comes out at 2.35 MHz.
Here's a pic of the result data at 300 MHz:
I'm just letting it run for a while at 300 to see how it holds up. Chips and heat sink get fairly hot to touch but I have just convection cooling for now. According to IR thermometer the heat sink is about 54C and the chip may be about 63C.
I've got it running at 300MHz and it's much more reliable than at lower speeds. I now have 2 chips doing 600 MH/s total with fairly long periods with zero HW errors.
I tried several capacitor values for result capture and the 30pF works well up to about 360MHz. At 380MHz it's lost sync. I tried a brief run at 360 MHz and it worked ok. I need to get a fan working before I run extended tests at higher clocks.
I had to fiddle a lot with the work unit cycle timing. Seems I don't know what's going on because calculated times weren't right. By trial and error I adjusted it to get very few duplicates. I've also implemented code to only update clock cfg when it changes, not every work unit. But I haven't altered the result capture code yet - so even with no extra schmitt buffers and slow result code it's actually doing ok. At 300 MHz the result data comes out at 2.35 MHz.
Here's a pic of the result data at 300 MHz:
I'm just letting it run for a while at 300 to see how it holds up. Chips and heat sink get fairly hot to touch but I have just convection cooling for now. According to IR thermometer the heat sink is about 54C and the chip may be about 63C.