[STM32F103C8T6] SPI1 does not send any data

[Toy-Jie]

STM32F103C8T6

RCC->APB2ENR |= RCC_APB2ENR_AFIOEN; AFIO->MAPR |= AFIO_MAPR_SPI1_REMAP; SPI.begin(); SPI.transfer(0xAA); 

SCK -> PB3
MISO -> PB4
MOSI -> PB5

Using an oscilloscope to check, no data is transmitted.

[fpistm]

Which target you used? Generic? BluePill?

[fpistm]

As far as I can tell (as I don't know your configuration), you use the default SPI instance but it does not use the pin you expect.
So change them following this wiki and no need to access registers it is done by the SPIClass.
https://github.com/stm32duino/Arduino_Core_STM32/wiki/API#change-default-spi-instance-pins