Delay_uS Errors

[ForceField]

Beware of errors in the Delay_uS function .

Fixed but not mentioned in Ver 3.210. so if you recompile old code you might have timing problems if you have tweaked timing loops.

Prior to 3.210 with 4MHZ clock

Delay_us(764) Gives 764uS
Delay_us(766) Gives 731uS
Delay_us(767) Gives 612uS
Delay_us(768) Gives 733uS

Ver 3.210 with 4MHZ clock

Delay_us(764) Gives 764uS
Delay_us(766) Gives 765uS
Delay_us(767) Gives 766uS
Delay_us(768) Gives 765uS

As you can see if you were using 764us their is no problem but 767us has a 155uS error in versions prior to 3.210.

No doubt there are other values that would give problems and also that other clock frequencies would produce different results.


I used the Stopwatch in Mplab with a Break Point before and after the Delay to check the timing.

Geoff

[Guest]

3.191 An accuracy problem in the delay functions is fixed