Hi PICer friends,

I'm using the 16F877 for the first time and I have trouble to start the xt
oscillator.

the connection on the 16F877 are:

vcc - to pin 11 - 32 wired togheter
gnd - to pin 12 - 31 wired togheter
mclr - to wcc thorught a resistor of 10K
xt osc - to pin 13 and 22 pf capacitor to gnd
xt osc - to pin 14 and 22 pf capacitor to gnd
rb3 - floating  (but have been tested connected to the vcc and gnd)

the xt are a 4 Mhz quartz

Using the blink8x.bas sample program in PBP 2.2 I compile it and I'm able to
load the hex into the pic and I can read back the code (that means the PIC
is working) but the oscillator do not start.

On pin 14 I can see with a scope a stable level of 2,6 volt and on pin 13 a
stable level of 2,0 volt .

Dear PICer friends, do you have any idea to help me to solve this problem?


Ciao

Leo


For reference purpose you can see the PBP blink8x.bas source:

i       var     byte    ' Define loop variable
LEDS    var     PORTD   ' Alias PORTD to LEDS
TRISD = %00000000       ' Set PORTD to all output
loop:   LEDS = 1        ' First LED on
Pause 500       ' Delay for .5 seconds
For i = 1 to 7  ' Go through For..Next loop 7 times
LEDS = LEDS << 1        ' Shift on LED one to left
Pause 500       ' Delay for .5 seconds
Next i
Goto loop       ' Go back to loop and blink LED forever
End