KEA8 internal temperature sensor

[alessiodemarchi]

I try to use the internal temperature sensor, I'm using kea8 kinetis microcontroller.

When I sample an ordinary analog input, from external pin, it is all right, but when I try to sample an internal analog channel (Vbandgap or temperature sensor) the value that I have obtained is not consistent, very unstable and change if I start the conversion mode. For example, starting the bandgap sampling by:

ADC_SC1 &= ~0x0000001f;

ADC_SC1 |= 23;   // sampling bandgap channel

obtain the result from about 0x300 to 0xaff

elsewhere by setting

ACD_SC1 = 23 | INTERRUPT_ENABLE_MASK;

the result is from 0x100 to 0x12f;

The ADC is configured for long sample time and with different clock frequency (busclock = 5 to 20 MHz, ADCLK = busclock /4 to 16).

Any suggestion to solve my problem?

[egoodii]

I can't especially help with your 'inconsistent ADC reads' -- you will certainly need to solve THAT!  (Did you enable the bandgap device?).

But as for AN3031, I highly recommend my more comprehensive post:

On-chip temperature Calculations 

[Jonathan_Iglesias]

Hello Alessio De Marchi,

I apologize for this delay, please check this Application note, it is for 8bit but  the process is the same  hope this help you solve your problem.

have a great day !

Best Regards