Knowledge Base

The instruction

     SPxPoll1   0,!CPU

will return the processor reset flags in U0. These flags indicate the cause of the most recent hardware reset of the processor chip. Note that these are the actual underlying processor, not the SPLat virtual processor. Note also that these only apply to products based on the 68HC908GP32 processor (SL99, MMi99, JM01). Please contact us if you intend to use these flags.

The flags are:

BitMeaning
0WarmBoot D>=20
1Low voltage reset. Processor received too little supply voltage
2Always 0
3Illegal address reset. Please report
4Illegal OpCode reset. Please report
5Watchdog timer reset. Please report
6Processor reset pin
7Power on reset

Of these, 7 is the one that should occur most frequently. 1 might suggest a power supply problem or hardware fault. 3, 4 and 5 would suggest a problem in our Firmware, and you should report these along with as much information as possible about how they came about.