pulse simulation

[nicolasronan]

hello
i want simulate a cycle rpm sensor for automotive.
http://www.geea.org/IMG/swf/capteur_vitesse_6.swf

the frequency must be able.
i ve test this code (!!! it s not the same cycle of the picture)
' _!-!_!-!__!--!_!-!_!-!

' pic16F877

' Variable
W0 var word
W1 var word
i var byte
up var PORTB.4
dn var PORTB.5
w0=0
i=0
'DN Define frequency down button
'UP Define frequency up button
PO con 3 ' Define pulse output pin

low PO ' Initialize output polarity
inc:
If (up = 1) Or (W0 = 10000) Then decr ' Increment freq on button
W0 = W0 + 10

decr:
If (dn = 1) Or (W0 = 0)Then pulse ' Decrement freq on button
W0 = W0 - 10

pulse:
for i =1 to 38
Pulsout 3,W0 ' Generate pulse
Pause W0/100 ' Intra-pulse delay
next i
Pulsout 3,W0
W1=W0*2
Pause W1/100
Pulsout 3,W1

Goto inc ' Forever

this code is ok but not optimized with button
how do? use pulsout or pwm?

thank

[Acetronics2]

Hi, Nicolas

Use DT interrupts !!! ... it's not so difficult to use.

http://www.picbasic.co.uk/forum/showthread.php?t=3251

or a little trick I discovered :

insert " DEFINE INTHAND _INC" at the top of the program ... This places a "GOTO _INC" at location 00004 of the ASM program.

Now trim the interrupt register ( INTCON) to allow an " interrupt on PortB Change "

Place a correct preset value for W0 ... 0 is not a good value !!! ( in "decr:" nor !!! )

Place a "GOTO PULSE " before "inc"

Think to re-enable interrupts, placing " INTCON.7 = 1" just past "pulse" label

last, change "GOTO inc" to "GOTO pulse"

That should go at first...

Next step will be to use BUTTON instead of IF-THEN ... just to use the Auto-repeat feature ...


One more step ...

Have a look to Motorola ( yessss ... Freescale !!! ) "TPUPN xx" Application Notes ...

really Great !!!

http://www.bgsoflex.com/megasquirt.html


Alain

[nicolasronan]

how place a "GOTO _INC" in microcode studio.
interrupt register ( INTCON) to allow an " interrupt on PortB : INTCON=00001000 , it s ok?
thank

[nicolasronan]

if i use
ASM
GOTO_INC
ENDASM
it 's ok?

[Acetronics2]

and how to place it in location 4 ????

D.E.F.I.N.E. !!!!!

Alain

[nicolasronan]

sorry bur i dont understand how use interrupt on a port.
i m bad