Programm ends up in Dummy Handler (Hard Fault)

Hi there After changing only a little in my Code, the Application always ends up in the DummyHandler(); the error occurs after that code: if (xSemaphoreTakeFromISR(uartirq, portMAX_Delay)) (selfwirtten code) ldr r0, [r6] movs r1, #0 mov.w r2, #4294967295 blx r5 cmp ro, #0 beq #250 if(prvISQueueEmpty(pxQueue) != pdFALSE) (out of the FreeRTOS/queue.c) cmp.w r8, #0 bne 42 from here it jumps into the Dummy Handler. Unfortunately i have no clue what this error is related to? Could there be a memory fault? Thanks in advance for any help.

Programm ends up in Dummy Handler (Hard Fault)

When you say the code is self written do you mean you wrote a function that tries to block an ISR to wait for a semaphore? If so then that is not a valid thing to do – interrupts are under the control of the hardware, not the FreeRTOS scheduler. Otherwise you are just misusing the second parameter as it is not a block time. Please refer to the API documentation online.