Breaking News
Comments
Newest First | Oldest First | Threaded View
StephenTo
User Rank
Rookie
re: Microcontroller-based temperature sensors—Accuracy considerations
StephenTo   9/1/2012 8:28:48 PM
NO RATINGS
Thank you all for your comments. Self-heating can affect all temperature sensors mentioned in the this article. It can be minimized by controlling the power consumption/dissipation of the sensor. Furthermore, self-heating in integrated sensors can be treated as an offset error and minimized by the second calibration technique. In the resistive transducer case, a ratiometric configuration is indeed a powerful technique to eliminate ADC voltage reference error. I encourage readers to explore and evaluate all types of temperature sensors for the desired application. For those interested in thermistors, SPLatman's tutorial and linearization looks like a good resource. For those interested in the C8051F39x, below are the entire contents in main() to obtain and +/- 2'C measurement: // Disable watchdog timer PCA0MD &= ~0x04; // Change SFRPAGE to access TS0CN register SFRPAGE = TS0CN_PAGE; // Start temp sensor conversion TS0CN |= 0x80; TS0CN &= ~0x80; // Wait for conversion to complete while ((TS0CN & 0x40) != 0x40); // Clear finished flag TS0CN &= ~0x40; // Change SFRPAGE to access TS0DAT register SFRPAGE = TS0DAT_PAGE; // Save temperature in degrees C myTemp = TS0DAT; while(1);

kendallcp
User Rank
Rookie
re: Microcontroller-based temperature sensors—Accuracy considerations
kendallcp   8/30/2012 8:41:50 AM
NO RATINGS
Agree about the great value-for-money of thermistors. The usual measurement method is ratiometric to a reference resistor, also, and a 0.1% resistor is far cheaper than a 0.1% voltage reference. So the comment in the article about ADC reference affecting the results isn't correct in the resistive transducer case. Really like the tutorial on Excel polynomial fitting BTW, SPLatMan! How I missed this capability for so many years I'll never know.

SPLatMan
User Rank
Manager
re: Microcontroller-based temperature sensors—Accuracy considerations
SPLatMan   8/30/2012 7:38:01 AM
NO RATINGS
Sad. Thermistors are not linear. RTD's are approximately linear. MCUs have internal temperature rise, which was not mentioned. An on-chip temp sensor is fine - for measuring die temperature. In terms of bang for buck thermistors take the prize, IMHO. As a rule of thumb, % accuracy of the thermistor is about the same as 'F accuracy. Betatherm and the like have thermistors down to 0.05'C accuracy, out of the box. Common or garden 2% thermistors are about as accurate as premium grade semiconductor devices. We routinely get 0.1'C resolution with a 10-bit ADC. Thermistor tutorial, including linearization: http://www.splatco.com/skb/1856.htm

CMathas
User Rank
Blogger
re: Microcontroller-based temperature sensors—Accuracy considerations
CMathas   8/29/2012 8:28:05 PM
NO RATINGS
Maybe you can expand...

jc07
User Rank
Rookie
re: Microcontroller-based temperature sensors—Accuracy considerations
jc07   8/29/2012 7:12:24 PM
NO RATINGS
First!



Flash Poll
Top Comments of the Week
Like Us on Facebook
EE Times on Twitter
EE Times Twitter Feed

Datasheets.com Parts Search

185 million searchable parts
(please enter a part number or hit search to begin)
EE Life
Frankenstein's Fix, Teardowns, Sideshows, Design Contests, Reader Content & More
Max Maxfield

Vetinari Clock: Decisions, Decisions, Decisions …
Max Maxfield
22 comments
Things are bouncing merrily along with regard to my uber-cool Vetinari Clock project. The wooden cabinet is being handcrafted by my chum Bob (a master carpenter) using an amazing ...

Jolt Judges and Andrew Binstock

Jolt Awards: The Best Books
Jolt Judges and Andrew Binstock
1 Comment
As we do every year, Dr. Dobb's recognizes the best books of the last 12 months via the Jolt Awards -- our cycle of product awards given out every two months in each of six categories. No ...

Engineering Investigations

Air Conditioner Falls From Window, Still Works
Engineering Investigations
2 comments
It's autumn in New England. The leaves are turning to red, orange, and gold, my roses are in their second bloom, and it's time to remove the air conditioner from the window. On September ...

David Blaza

The Other Tesla
David Blaza
5 comments
I find myself going to Kickstarter and Indiegogo on a regular basis these days because they have become real innovation marketplaces. As far as I'm concerned, this is where a lot of cool ...