Thanks for that.
My original circuit had three octal darlingtons (ULN 2803) with inputs directly coupled to Ports A, C and D I have also connected leds with 680ohms to each pin so that I can see what the ports outputs are. A test program switched on and off each led in turn thru ports D C and A in that order and worked OK. Problem arose when tryin to switch on all of the A port bits and leave them on. I have now disconnected ther darlington from port a and written the following simple test program:
Code:
@ DEVICE pic16f887,intrc_osc_noclkout
PORTD = 0
PORTA = 0
PORTC = 0
TRISD = 0
TRISA = 0
TRISC = 0
portA.0 = 1
pause 500
porta.1 = 1
pause 500
porta.2 =1
pause 500
porta.3 = 1
pause 500
porta.4 = 1
pause 500
porta.5 = 1
pause 500
porta.6 = 1
pause 500
porta.7 = 1
end
I have just run this program and
1. When Microcode studio fired up the Pickit2 the voltage Vdd had been set down to 3.3
2. I turned up Vdd to 5 volts and programmed the chip.
LEDs 0,1,2,3 tuswitched on and then off after the delay. LED 4 switched on and stayed on, LED 5 switched on and then off again after the delay and then LEDs 6 and seven switched on and remainedon. I can see no logic inthis although I have that horrible feeling that it is staring me in the face !