While reading the ‘board.h’ of the Matek H743 Mini board, I stumbled upon this:
After noticing that the two different seemingly similar macro gets sent independently, I wondered what the difference between these two macros are:
The CLKDIV macros above are used in the NuttX in the following part:
This then gets used in the
stm32_clock() function for following cases below.
Enabling MMC normal clocking:
SD card normal operation clocking:
And these cases seem to be defined in this enum for SDIO clock:
So it seems that SD card and MMC cards have a different specification, and hence they are called that way.
So for now it just seems like we need to define both cases in the
board.h file. However, I am still wondering what the
XFR stands for, and why we truly need to set MMC and SD cases separately like it is currently done
- STM RM0433 Reference manual