STM32F103 internal temperature sensor

[peter23]

Posted on June 11, 2013 at 14:12

Hi!

I have seen an earlier discussion with the device stm32F051 or F205 regarding the TS_CAL1 and 2 values. My question is, are these values applicable for the STM32F103 device? Cannot find any references to them in the manuals or guides. I get the feeling that these values are not available with this device. But maybe there is another solution to get more accurate values of the temperature. I haven't been able to find the TS_CAL values in the manuals for device F051 or 205 either, maybe this feature has changed lately? Regards Peter #stm32f103

[Tesla DeLorean]

Posted on June 11, 2013 at 14:48

One might assume it is simply not calibrated as part of the test procedure.

Measuring external temp is going to be highly dependent on the packaging, and the thermal properties of the PCB and surrounding parts.

[peter23]

Posted on June 13, 2013 at 17:49

Thanks Clive,

my question right now is if it is possible to get more accurate temperature readings from the STM32F103 in some way. Like the way with calibration values available per chip. We would like to have some better accuracy than what the ref.manual says the chip provide. ''The temperature sensor output voltage changes linearly with temperature. The offset of thisline varies from chip to chip due to process variation (up to 45 °C from one chip to another).'' I am aware of that we will measure the chip temperature which can vary a lot.but our application will not consume much power and we don't have any other heaters nearby either. So the circuit board temperature will probably not differ too much from the ''room'' temperature. Right now I  don't know where to go to get the right infomation about this. Have to figure this out. Regards Peter

[John F.]

Posted on June 13, 2013 at 17:54

If you can use an external IC. Microchip and others make comparatively low cost temperature sensors. See the MCP9800 I2C bus device for example for a digital output.

[raptorhal2]

Posted on June 13, 2013 at 18:18

The only way to improve internal sensor accuracy is to provide an offset correction with each chip. This may or not be practical depending on your production circumstances.

An NTC resister in a resister divider circuit is a simple external sensor that will require an external ADC channel. A long sample time will likely be needed, or use a buffer amp. Cheers, Hal

[peter23]

Posted on June 13, 2013 at 18:20

Thanks John,

we may need to add an external sensor if the internal one cannot provide reading good enough. But it is easier and cheaper if we could make use of the internal senor. But we have to see. Right now I am trying to figure out for which STM32 chips these calibration are valid. Peter

[peter23]

Posted on June 13, 2013 at 18:22

Thanks for the tip Hal.

[Tesla DeLorean]

Posted on June 13, 2013 at 19:45

Can you calibrate your devices are part of you production or final testing?

Certainly would reduce the 45C level of uncertainty.

[peter23]

Posted on June 14, 2013 at 11:33

Hi Clive,

I may be possible to calibrate this in production, but it could be inpractical. Peter