Noob cnt question
Benj
Posts: 66
I have been trying to figure out how to effectively use cnt and have had some success but am running into a sticking point. My code:
I think the above code should print out "total" every second, but it does not do that. Instead it prints out "total" about every 54 seconds. Instead of it waiting for cnt+80_000_000, it seems to cycle all the way around until it again reaches that value for cnt. I did some more testing to see that cnt takes about 54 seconds to go from 0, back around to 0. What am I doing wrong?
CON
_clkmode = xtal1 + pll16x
_xinfreq = 5_000_000
OBJ
text : "vga_text"
VAR
word total
word OneSec
word TimeBase
PUB Start
OneSec := clkfreq
TimeBase := cnt
repeat
waitcnt(TimeBase += OneSec)
total += 1
text.dec(total)
I think the above code should print out "total" every second, but it does not do that. Instead it prints out "total" about every 54 seconds. Instead of it waiting for cnt+80_000_000, it seems to cycle all the way around until it again reaches that value for cnt. I did some more testing to see that cnt takes about 54 seconds to go from 0, back around to 0. What am I doing wrong?
Comments
2) 54 seconds is approximately 2^32 clock "ticks" at 80MHz. That should always give you a hint that you've got a problem with a waitcnt.