> =

> First I make sure thet in BIOS the Parallel Port is set to
> 'Std. Bi-Direct.' =

> =

> When:
> D6 is logical 0 the voltage on it is -0.68V
> =

> on E of the C556B PNP tranzistor measured 12.09V
> on B measured 11.97V
> on C measured 0.00V
> =

> on E of the BC548B NPN tranzistor measured -0,00V
> on B measured 0.73V
> on C measured 0.00V
> =

> when:
> D6 is logical 1 the voltage on it is -0.87V
> =

> on E of the C556B PNP tranzistor measured 12.09V
> on B measured 11.97V
> on C measured 0.00V
> =

> on E of the BC548B NPN tranzistor measured -0,00V
> on B measured 0.73V
> on C measured 0.00V
> =


D6 does not appear to change. It is always low. Disconnect everything from =
the =

output pin and check that you can get D6 to swing between low and high (bet=
ween =

close to 0V - low, to about 3 to 5 V - high).

It seems a bit odd that you get almost -1V on the output pin. Are you measu=
ring =

it with respect to ground in the LPT port? Do you have ground connected =

correctly between the PC and your circuit? Specifically, the ground from yo=
ur =

12V supply must be connected to ground in the LPT port.

Can you get the VPP (MCLR) voltage to get to 12V by manually connecting the =

input of U3 and U5 to a high TTL voltage (3 to 5V) when D6 is disconnected? =


/Ruben


=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D
Ruben J=F6nsson
AB Liros Electronic
Box 9124, 200 39 Malm=F6, Sweden
TEL INT +46 40142078
FAX INT +46 40947388
ruben@pp.sbbs.se
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D

-- =

http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist