I'm working with the STM32H7 MCU and I have three memories (1 flash, and 2 fram) connected to SDPI1 interface. According to flash datasheet, max SPI clock can be up to 80MHz. Nevertheless, when having the SPI SCK set at 7.5MHz (SPI peripheral clock is 60MHz), I have problems when reading from the flash. If I set SPI SCK at 1.5MHz (presscaler set to 32 instead of 8), then the flash reading process is perfect.
Why have I to set such low frequency? Does the number of connected devices influence the maximum clock frequency? In what regards hardware, I have tested the SCK signal with a scope even when working at 7.5MHz, and it was looking OK.
All the best,
Dani.
