I'm trying to use the SPI Bootloader of the STM32L476RG.
To do so, I set up an other STM32 device running an SPI master (Frame Format = Motorola, Data Size = 8 Bits, First Bit = MSB First, Baud Rate = 62.5 KBits/s, CPOL = Low, CPHA = 1 Edge, CRC Calculation = Disable, NSSP Mode = Enabled, NSS Signal Type = Output Hardware). The SPI master is connected to SPI2 of the STM32L476.
I pull the BOOT0 pin to VDD and reset the device. After waiting one seconds, the master sends 0x5A, 0x00, 0x00. The answer is monitored via oscilloscope and is: 0xA5, 0xA5, 0xA5. According to AN4286, the 3rd byte should either be 0x79 or 0x1F. Even if I send additional 0x00's, the device always responses with 0xA5. So it looks like the SPI synchronization is not working properly.
Serving the bootloader with USART worked properly.
What am I doing wrong? Do you have any recommendations?
Thanks a lot