My STM32U031R8T6U (CPU: UID=0x20353953_39365013_0030007C Lot#=59S96P Wafer#=19 X=48 Y=124 FLASH=64KB) has 0xFFFF under VREFINT_CAL_ADDR - the Vrefint calibration data are absent.
C code:
printf("\r\n *VREFINT_CAL_ADDR=%u", *VREFINT_CAL_ADDR);
Output:
*VREFINT_CAL_ADDR=65535
This issue seems to be similar to the one described in:
https://community.st.com/t5/stm32-mcus-products/stm32u073cc-vrefint-calibration-data-missing-value-wrong/m-p/716948#M259968
but hasn't been mentioned in the STM32U031 Errata Sheets.
