GOSUB Response Time

[MBB]

I have the following code that is part of a larger program:

;Chip Settings
#chip 16F876,20
#config LVP=OFF, PWRTE=ON, OSC=HS

#define T_1 PORTB.3
#define Rec_1 PORTA.0

;Variables
Dim A_Cnt As word

Dir T_1 OUT
Dir Rec_1 IN

SET T_1 ON
GOSUB Chk_Rec
‘******************************************

Sub Chk_Rec
A_Cnt = 0

Loop1:

A_Cnt = A_Cnt + 1

If Rec_1 = 1 then
SET T_1 OFF
locate 1, 15
print A_Cnt
Goto Loop2
End If

Goto Loop1

Loop2:

End Sub

When I run this code, I get an A_Cnt of 1 meaning the IF statement immediately "saw" PORTA.0 (T_1) as a high.

When I connect an oscilloscope to PORTB.3 (T_1), I measure a pulse width of 1.4 milliseconds meaning it took 1.4 milliseconds for the PIC to go from the main program to the sub-routine.

1.4 milliseconds seems like a very long time for the PIC to perform this simple operation.

Am I doing something wrong?

[gcha44]

Hi,
to call sub Chk_rec , you just type  "Chk_rec" , not  "gosub Chk_rec"
If you want use "gosub"  then Ch_rec is a label you must type like that   "Chk_rec:"   
and it ends with the "return" keyword

Regards
GC

[MBB]

I finally got to try your suggestion and it worked!

Thanks for your help