I wonder why this creates HardFaultError rarely and randomly. Thanks

[Johanan1]

rxBuf is uint8_t array.

       // this creats HardFault sometimes:
         id = *(uint32_t *)&rxBuf[i];
//----------------------------------------------------
      // but this works OK forever:
        id = rxBuf[i + 3];
	id <<= 8;
	id += rxBuf[i + 2];
	id <<= 8;
	id += rxBuf[i + 1];
	id <<= 8;
	id += rxBuf[i + 0];

[Piranha]

Because it can create unaligned memory access on a CPU (Cortex-M0), which doesn't support that.

https://developer.arm.com/documentation/dui0497/a/the-cortex-m0-instruction-set/about-the-instruction-descriptions/address-alignment

https://stackoverflow.com/questions/14671595/what-does-it-mean-when-my-cpu-doesnt-support-unaligned-memory-access

[Johanan1]

Of course. Thanks a lot. I am kicking myself.:sad_but_relieved_face: