Hi,
I have compiled Marlin 2.0.x for STM32F103CB and Malyan M200 board but uploaded to a "Blue Pill" board using PIO. Since it's basically the same chip I expect most features to work. Serial interface and stepper outputs tested fine but can't initialize the SD card (card works fine on a RAMPS 1.4). Issuing M21 responds with a failure message. To make sure the wiring between the board and SD card is fine I uploaded the CardInfo.ino sketch (Arduino example) which works fine.

I also made sure SDSupport is defined in the config file, played with different SPI_SPEED and SPI_SD_INIT_RATE values but did not help.

Hooked the SPI pins to my scope and can see that the first 80 clock cycles are performed followed by CMD0 command: 0x40 0x00 0x00 0x00 0x00 0x95 but no response from the card. The clock rate also seemed to be at around 250kHz.

Any idea where I can look next?