An electronic circuit includes a microcontroller processor (410), a peripheral (420) coupled with the processor, an endian circuit (470) coupled with the processor and the peripheral to selectively provide different endianess modes of operation, and a detection circuit (140) to detect a failure to select a given endianess, whereby inadvertent switch of endianess due to faults is avoided. Other circuits, devices, systems, methods of operation and processes of manufacture are also disclosed.