Pulses on PC13 pin of STM32F103C6T6

[embeddeddesignblog]

The LED connected to the Blue Pill board on PC13 pin blinks after power up. Just to check the pulses on that pin, probed and seeing the attached pulses. Why are these pulses generated? I haven't seen any data about this in any of the documents? I did not see the pulses on other pins. Randomly checked PC15, PA4, P5.

[TDK]

The blue pill generally has an arduino-style bootloader. The cause is in there somewhere, or in the firmware you have currently loaded. It's not anything that is inherently done by the STM32 during startup.

[embeddeddesignblog]

@TDK Thank you fir the insight.

I downloaded a USB boot loader (.bin file from third party) to access the USB port for programming. Except that I did not have any application code running. The interesting point in that waveform is the different frequencies used.

After trying to get info on PC13 toggling which is not existing and with your reply, I am coming to a conclusion that it may not be inherently from STM32. I will try to flash a new code to see whats happening..