Cannot read VREFINT Accurately on STM8L052C6 48 pin package

[iron]

Posted on December 14, 2012 at 03:12

I route VREFINT to an output pin and it reads correctly at 1.22V.

If I vary my input voltage, the VREFINT raw count value drifts around between 1100 and 1300 counts using VDD at 3.22V.  The higher the voltage, the higher the count.I checked VDD going in and it is rock solid.  Same with VREFINT going out the PC6 (?) pin.I am in single conversion mode using PF0 (ADCIN24) as my input pin.Any help appreciated.  thanks, Jim  #adc

[iron]

Posted on December 14, 2012 at 04:07I figured it out.  Set ADON bit to 1 before setting SQR registers.

[vivavivy]

Posted on March 09, 2015 at 11:37

Hi,

could you please explain me which step you took in order to route the Vref output to a pin?I'm using the same STM8L052 you are using, and I tried setting bit CH7E of RI_IOSR1 register in order to route Vref out of PC2, but I see nothing...I assume bit VREFOUTEN of COMP_CSR3 is always set because in 052 family there is no comparators, therefore I assume there is no COMP_CSR3 register. Am I right?Thanks,Vivy

[vivavivy]

Posted on March 09, 2015 at 12:27Ok, I found out. Even if COMP_CSR3 register is not defined as 052 family microprocessor port, the register must be set to enable Vrefouten. This line do the trick:*((uint8_t *) (uint16_t)0x5442) |= 1;