pin three on parallel port

[Gaston]

i built the programing board on nigel's page and im using the winpicpro. i can't get it to find the port. if i put my scope on pin 3 of the parallel port sould i see the clock? and am i right that the only way the computer is going to know that the board is there is through pin 10 which is the only dta in pin? i have been going over the board with a fine tooth comb and need a fresh approach. i haven't ruled out a bacd port on the mother board either. any tricks for testing it?

 

[kchriste]

if i put my scope on pin 3 of the parallel port sould i see the clock

Not until WinPicPro is working and you are in the middle of reading or writing to a PIC.

am i right that the only way the computer is going to know that the board is there is through pin 10 which is the only dta in pin?

It detects the programmer by sending data out pin 2 and reading it back on pin 10 of the parallel port. You can test your computer setup by putting loop back wire from pin 2 to pin 10 on the parallel port. WinPicPro will then think it sees a programmer on the port.

i haven't ruled out a bacd port on the mother board either.

It is possible. Did you download and install the parallel port driver as well?:
**broken link removed**

 

[Gaston]

i am running 98se. am i correct that you don't need the port driver for 98? i did install the driver though just incase. or would that be a problem? i will jump pin two to ten in a few minuts and see what happens

 

[Gaston]

i just jumped 2 and ten and it found the port. thanks. know i just have to figure out why the board isn't working

 

[Gaston]

i have something weird going on or i am misunderstanding something. i put a function gererator on pin three of the 74ls05 and a logic probe on pin four. pin four just stays low. i changed the 74ls05 and got the same thing. i took it out of the circuit and mocked it up on a breadboard by itselt and get the same results. all of the inverters do the same ( one and two , five and six ...)but if i put the input on four three works as an output. is that supposed to be like that?

 

[kchriste]

i put a function gererator on pin three of the 74ls05 and a logic probe on pin four.

You have to be carefull using a function generator to do this because they don't always swing from 0-5V. Most will swing from a negative voltage below ground to a positive voltage.

pin four just stays low.

Don't forget that a 74LS05 has a open collector outputs and needs pullup resistors on the outputs to function. The 74LS06 is a better choice for this design (I don't know why they spec a LS05) because it's output transistors are rated higher than the LS05's rating of 7V

but if i put the input on four three works as an output. is that supposed to be like that?

It's definately NOT supposed to work that way because pin 4 is an output. You aren't looking at the chip backwards and really inputting to pin11 and outputting on pin10 are you?

 

[Gaston]

you were right about the function generator.on the breadboard pin four is low and when i bring pin three low with a jumper pin four goes high. however i can't duplicate this in the circuit. here is what i get in the circuit without the parallel cable connected.pin two- no light on logic probe-bring pin one low-pin two goes low. pin four-low-bring pin three low- no change.pin six -low-bring pin five low- six goes high.pin eight- low- bring pin nine low- no change. pin ten high- bring pin eleven low-no change- bring pin elenen high ten goes low.pin twelve- low- bring pin thirteen low twelve goes high. i assume pin ten is high because eleven is being held low by the connection in the circuit to four

 

[Gaston]

i pulled the 7505 out and pin four in the socket is high. so pin four on the 7405 is sinking the voltage. i just can't get it to stop by bringing pin three low. i checked r6 and its 10k and i checked c4 with my ohm meter and it doesn't pass dc. i even put a 7404 in there and i get the same thing. ive been workin g on this thing since noon... talk about a tough nut to crack.

 

[kchriste]

See if you can find a 74LS06 because the 74LS05 is being operated out of spec with about 13V on pins 2,8 & 12. It is only rated for 7V on these pins. I know others have gotten away with it, but the chips you have may not be able to handle the 13V and thus are doing weird things. The 74LS06 will handle up to 30V on it's outputs.

i even put a 7404 in there and i get the same thing.

A LS04 would also behave strangely. Try removing the 78L08 and bridging where pins 2&3 went to put 5V on the VPP line instead (measure the voltage to be sure it is only 5V). Then do your checks with the logic probe again. If it appears to work (especially pins 3,4,10 & 11) then it is definately because the LS05 is breaking down due to being operated out of spec and it needs to be replaced with a LS06 and the 78L08 put back as per the original diagram.

 

[Gaston]

good advice. i think your onto something. its saturday morning now. after the coffee is done brewing i'll give it a try. thanks

 

[Gaston]

i just tried eliminating the 13 volts and making it all 5. still the same thing. i even put a fresh 74ls05. could something be holding pin four low? i guess i could check the resistance of pin four to ground and see if there is low resistance. i don't see what else it could be because it works on a breadboard. or mabey i'll mock it up on a breadboard and keep adding more of the cuircuitry until it stops working. but that would only tell me if the schematic is wrong. i'm sure others have used it with success.

 

[Gaston]

i checked the resistance to ground on pin four and it was 12k. i removed the chip and it was the same. i removed the cap (c3) and it was the same. i traced the circuit all the way back to the 40 pin socket and checked every inch of the traces. one of the traces on the veriboard went way across the board and had an extremely small amount of solder bridging the gap to the next trace. i had to used my magnifing glass to see it. i confirmed it with my ohm meter. i passed the soldering iron down the gap. checked it the way i have been doing with the logic probe and it worked properly. i hooked it up to the pc and i have $378 : ) . 12 hours down the toilet for a peice of solder. thanks for your help. its nice to be able to talk to some one about electronics.

 

[kchriste]

i hooked it up to the pc and i have $378

I was kinda sleeply when a read this and my first thought was, "How did he make any money on this?" Now it's just a matter of programming a PIC with it.

thanks for your help. its nice to be able to talk to some one about electronics.

No problem. It's a good forum for that, with lots of good people here.

 

[Gaston]

my goal is to program my first pick by the end of this weekend. i am doing nigel's first tutorial on the led flashing. but on a breadboard. i think i have the hexfile right. i will find out in a little while