Quote from: BkkCoins on July 05, 2013, 06:43:18 AM

Quote from: Bluestreak66 on July 05, 2013, 06:10:23 AM

Quote from: BkkCoins on July 05, 2013, 04:55:56 AM

That temp reading is right but it's not close to the ASIC mounted. On next board revision I'm going to place the thermistor in the center of a quad of 4 ASICs so it should get a closer approximation, and of course once I do some testing I'll add an offset adjustment. Yes, it's actually 34C at my work bench Cry

If you put a thermistor per 4 asics then wired them series parallel you could get an average for entire board. How well does the heat conduct to the top layer? I wonder if adding some thermal vias to the thermistor would get it close to actual temp.

Good idea. I'll look into adding a via to help heat get to the thermistor. I was thinking about having sensors for each quad but didn't have enough inputs for individual monitoring. The idea of averaging via several is great because the thermistors are cheap. If I put two in series in parallel then I get 4 thermistors with the same total resistance. I do see some issues with this for situations where not all ASICs are installed or when one gets to critical temp when others are fine. In the latter case you're no worse off than just having one, for the 3 not monitored, but in the case with less ASICs the average of the installed ones would be impacted.

Also, I do have 2 pins available but they cannot be connected to resistors until after programming, and only if I have a bootloader present to do updates. They could be connected to an analog selector switch for choosing 1 of 4 thermistors.

Could you pass back the results of all of them?
It's easy enough in the mining software to decide which ones to ignore, but also to take note of when just one of them gets high.
At the moment ckolivas displays both temp0 and temp2 in the avalon (coz temp1 is apparently always zero) but I display the max of all temps in the bflsc (since with x-link in the future there could be e.g. 40 of them)