Wrapping an int8 Counter

jecottrell · Joined: 16 Jan 2005 Posts: 559 Location: Tucson, AZ

Hello All,

I'm going to use an int8 variable to number packets and simply increment the packet number with each packet sent. Is there any need to catch when the counter equals 255 and reset it to zero? Or is it safe to just allow it to roll over?

Thanks,

John

theteaman · Joined: 04 Aug 2006 Posts: 98

well at 8 bits 255 is the highest number representable.. so it should work a long as its unsigned

kender · Joined: 09 Aug 2004 Posts: 768 Location: Silicon Valley

MikeW · Joined: 15 Sep 2003 Posts: 184 Location: Warrington UK

my advice is it OK to just let it roll over.

done it for years

rnielsen · Joined: 23 Sep 2003 Posts: 852 Location: Utah

Counters and Timers pretty much use the same hardware. When the counter/timer register rolls over from 255 to 0, if enabled, an interrupt will occur allowing an event or special code to be executed. This type of 'roll over' is perfectly natural for the PIC. In fact, you could take advantage of this event to tell the rest of your program that it actually has rolled over.

Ronald