Hello,
I am using an STM32F437 MCU with Keil MDK-ARM V4.71a. My application (no RTOS) reads an SD Card on start up via the RL-ARM FFS. This has been working for a few years but I have now upgraded to Keil V4.74 (the last V4 release). Now when I run my code I get a Hard Fault when I call fopen(). I have tracked it down to __sys_open() but that's as far as I can go, as I don'y have __sys_open() source code. Any ideas on what the issue could be? Something seems to have changed between V4.71a and V4.74. I can't use V5 because this requires the RTX for FFS and for various reasons I need the code to be stand-alone. Thanks.