2025-06-12 11:26 AM
I have done a PCB Design with microcontroller STM32L071CZT6 as the mcu. PB15 which is a 5V tolerant pin is connected to a source of 4.9 V with a resistor 270 kOhm in between. I measured the voltage at the PB15 pin to be 4.9 V but, when I set it as Digital Input pin with no pull it does not read HIGH. But, I remember the previous batch of boards with the same design had this pin read HIGH by the same firmware.
2025-06-12 11:56 AM
Dump the GPIOB register values to double check correct settings.
The data sheet says: Input voltage on FT and FTf pins max. VDD+4.0, so applying 5V is illegal while the MCU is not powered. Can this be excluded?
hth
KnarfB
2025-06-12 12:28 PM
Related/duplicate?
STM32L071CBT6 issue While recieving Input for GPIO... - STMicroelectronics Community
Just a coincidence that you are both asking about PB15 input not reading high at 5V on the same chip?