Leaves the mainloop???

[richard]

no different to tris making pins input or output

[pescador]

PIC-AAAHH.pdf

see attached - I changed to LATs as suggested but I still cannot drive the base of my npn with the load in. If I remove the load and turn the FET on - its ok.

I dont get it.


#CONFIG
__config _CONFIG1, _FEXTOSC_OFF & _RSTOSC_HFINT32 & _CLKOUTEN_OFF & _CSWEN_ON & _FCMEN_ON
__config _CONFIG2, _MCLRE_ON & _PWRTE_OFF & _LPBOREN_OFF & _BOREN_ON & _BORV_LO & _ZCD_OFF & _PPS1WAY_OFF & _STVREN_ON
__config _CONFIG3, _WDTCPS_WDTCPS_11 & _WDTE_OFF & _WDTCWS_WDTCWS_6 & _WDTCCS_SC
__config _CONFIG4, _BBSIZE_BB512 & _BBEN_OFF & _SAFEN_OFF & _WRTAPP_OFF & _WRTB_OFF & _WRTC_OFF & _WRTSAF_OFF & _LVP_OFF
__config _CONFIG5, _CP_OFF
#ENDCONFIG


OSCCON1=%00000011
OSCCON2=%00000011

trisa = %11101100
trisc = %11111111

ANSELC = 0
ANSELA = 4


DEFINE OSC 4

FET var LATA.4 ' FET output
IG VAR PORTA.5 ' Ignition input
GREEN VAR LATA.0 ' TIMING LED
RED VAR LATA.1 ' FAULT LED

MAIN:
IF ig = 1 THEN
FET = 1
GREEN = 1
ELSE
FET = 0
GREEN = 0
ENDIF

[richard]

If I remove the load and turn the FET on - its ok.

what is the load ?
what happens with a smaller load ??

sounds like power supply , noise suppression and or wiring layout is inadequate

[pescador]

DC electronic load - it works at 1 amp - any higher it fails (PIC cant drive the base).. no noise - PS can handle 20 amps.. The base of the npn must be sinking too much current for the PIC pin to drive at first. Whats strange is if I disconnect the load the PIC pin drives it ok, add the load and it keeps working. Power cycle PIC and it wont turn on the load again unitl I disconnect load and connect again.

[richard]

is this your complete code ?

#CONFIG
__config _CONFIG1, _FEXTOSC_OFF & _RSTOSC_HFINT32 & _CLKOUTEN_OFF & _CSWEN_ON & _FCMEN_ON
__config _CONFIG2, _MCLRE_ON & _PWRTE_OFF & _LPBOREN_OFF & _BOREN_ON & _BORV_LO & _ZCD_OFF & _PPS1WAY_OFF & _STVREN_ON
__config _CONFIG3, _WDTCPS_WDTCPS_11 & _WDTE_OFF & _WDTCWS_WDTCWS_6 & _WDTCCS_SC
__config _CONFIG4, _BBSIZE_BB512 & _BBEN_OFF & _SAFEN_OFF & _WRTAPP_OFF & _WRTB_OFF & _WRTC_OFF & _WRTSAF_OFF & _LVP_OFF
__config _CONFIG5, _CP_OFF
#ENDCONFIG




OSCCON1=%00000011
OSCCON2=%00000011


trisa = %11101100
trisc = %11111111


ANSELC = 0
ANSELA = 4




DEFINE OSC 4


FET var LATA.4 ' FET output
IG VAR PORTA.5 ' Ignition input
GREEN VAR LATA.0 ' TIMING LED
RED VAR LATA.1 ' FAULT LED


MAIN:
IF ig = 1 THEN
FET = 1
GREEN = 1
ELSE
FET = 0
GREEN = 0
ENDIF

[pescador]

yes - thats my test code

[richard]

The base of the npn must be sinking too much current for the PIC pin to drive

with 6k in its collector and a hfe min of 100 the base current required is just a few microamps to drive it into saturation
the pic will barely know its there