We are working on 68HC11E9 processor. We are using the processor in expanded mode. We faced some issues related to ROMON. So we have added the test mode code in our firmware. We put the chip in test mode when we doubt the ROMON bit. But surprisingly, the CPU is executing this test mode code sometimes when its wired for normal mode operation. This is observed at power off/on and randomly also. Sometimes the device is working okay in normal mode. When it is switched off and on , it hangs. Sometimes when the device is working okay in normal mode, suddenly it goes to test mode and hangs. We have written one data in NVM when the device executes test mode code. From this we are able to see that it is going in test mode.
Can anybody help in this?
Thanks in advance!