Forum Discussion
Honored ContributorTEMPDIODE reading low
I'm reading the temp diode on a stratix IV fpga, and it reading about 50C below what it should be.
It is changing in regards to thermal heat and cooling, but it always seems about 50C too low. Thoughts?12 Replies
Altera_ForumJust an update on this in case anyone else has the same problem... we had a 2200pF cap placed between the terminals that didn't have enough time to charge up during the reading. We probably could've went with a smaller cap, but unpopulating it seemed to work very nicely.
- Altera_Forum
I've got TEMPDIODEP connected to AT and TEMPDIODEN connected to ATRTN.
- Altera_Forum
Truly I don't know how to use the ADC on an Actel Fusion AFS600 to monitor the temperature on a Stratix IV. You really shouldn't be looking at Altera's megafunction user's guide to solve this because you are not using the megafunction. I think you need to be talking to the Actel FAE to solve your problem.
Jake - Altera_Forum
Can you confirm that you are connected as shown in figure 2-77 on page 2-96 of the AFS600 datasheet?
http://www.actel.com/documents/fusion_ds.pdf Jake - Altera_Forum
An Actel Fusion AFS600...we're using the AT temp monitor pins.
- Altera_Forum
Which external ADC are you using?
Jake - Altera_Forum
Sorry, I was confused too. We are using an external ADC with a 12-bit resolution. That is why we are getting 0x414, and read -12C.
I'm still not sure why we are gettin 0x414 though. In the megafunction manual, table 4 shows a sign bit. Could this be screwing us up in the 12-bit read? - Altera_Forum
I'm confused. I thought the internal diode only provided 8 bits of resolution as indicated by the alttemp_sense megafunction user guide:
http://www.altera.com/literature/ug/ug_alttemp_sense.pdf Jake - Altera_Forum
I'm using the internal ADC. I think I'm getting the value 0x414....but the issue might be in my conversion.
- Altera_Forum
What value are you reading from the sensor (Digital value)? Are you using the internal ADC or an external ADC. If external, which sensor are you using?
Jake
