TreadBot

[mister_e]

Yeah it's one of those machine some may want to have hanging on their bench

Maybe your tube haven't the right specs, were to far of your PCB, or your exposure time was not appropriate. You have to use special wave lenght tube (UV). regular Black-light tube (or lamp)have nothing to do with that. I usually pre-heat my tube before for 1-2 minutes.... once again for safety sake.

Once you have did few experiments, you know how much time your exposure time will be... it's almost the same everytime.

At least you will scrap 1 big PCB. if you're using 2-3 tube, this MUST take less than 2.5 minutes.

1. Start the exposure lamps and hide major part of your whole PCB with an opaque material
2. wait at least 1.5 minutes
3. move the opaque material to reduce the 'hidden from UV' PCB area every 5-10 seconds
4. develop the whole PCB and look where your PCB look the best.

At the bottom of this link, it's almost what i said... but in english
http://www.turbokeu.com/myprojects/pcb.htm
Enjoy and have fun with the pcb etching and... drilling job

EDIT: i heard some use now ultraviolet LEDs...

[dragons_fire]

the board is done now, and some of the stuff is mounted to it. im using the pic18lf6585, which is the low voltage one (but should work from 2 - 5.5V) and i have a 5V 5A regulator. when i connect the battery without the chip in its socket, everything works fine, as soon as i stick the chip in, the PIC and the Regulator heat up... i havent let the smoke out "yet" but they did heat up lots, and might not be any good anymore... i checked to see if i had Vss or Vdd backwards (so when i put the chip in, it would short out) but everything looks good.





if anyone has any ideas of why its doing that, please let me know.. heres a pic of the bottom of the board on my first attempt with the toner transfer method. the top didnt turn out as good, but there is only 3 traces on the top, and they werent affected.


my last question for everyone is: For PICs that have multiple Vss and Vdd's, do they all need to be connected (they are on this board), or are they connected internally?

[mister_e]

All VSS and VDD have to be connected.

From what i see on your picture, there's few potential traces short-circuit. Assuming there's no routing mistake and the original design worked, You should do a visual inspection first then use you Multimeter.
<img SRC="http://www.picbasic.co.uk/forum/attachment.php?attachmentid=1538&stc=1&d=117673623 8">

Seems to be caused by a lack of etching time or toner transfer... i can't tell.

The overall layout and routing looks good, the final results... so so. I try to avoid 90 degree routing, the etching process work better. It have also other benefits in high frequency.

I also try to avoid unconnected 'ground plane dedicated' copper islands.

Check if there's any polarised capacitor connected backward.

[skimask]

my last question for everyone is: For PICs that have multiple Vss and Vdd's, do they all need to be connected (they are on this board), or are they connected internally?

All Vss's must be connected together outside of the chip, same with Vdd.

And nice job on the PCB...really. The only things I was going to mention...mister_e already covered them...

As far as overheating, with the PIC out of the socket and power disconnected, if you put a meter between any Vss and Vdd, what do you get for a resistance reading? How about a Vf reading (normally seen as a continuity test on a meter when really it measures a diode's forward voltage)... Now try it with the PIC in the socket and power still disconnected?
Then hook up the meter to Vdd & Vss, turn it on volts, put the PIC in the socket, and plug in power just long enough to read the meter. Did the meter come up to system voltage? In other words...dead short somewhere on the board?

[dragons_fire]

As far as overheating, with the PIC out of the socket and power disconnected, if you put a meter between any Vss and Vdd, what do you get for a resistance reading? How about a Vf reading (normally seen as a continuity test on a meter when really it measures a diode's forward voltage)... Now try it with the PIC in the socket and power still disconnected?
Then hook up the meter to Vdd & Vss, turn it on volts, put the PIC in the socket, and plug in power just long enough to read the meter. Did the meter come up to system voltage? In other words...dead short somewhere on the board?

1.036kohm across vdd and vss "with" and "without" the chip. i tried another regulator that isnt mounted to anything, and it comes back with the same reading.

5V without chip, 4.48V with chip

when i put my meter on the doide symbol (i have never used it before and dont know what it is), i get .324V without any power applied to the board (im assuming there isnt supposed to be)

[skimask]

1.036kohm across vdd and vss "with" and "without" the chip. i tried another regulator that isnt mounted to anything, and it comes back with the same reading.

1-ish Kohm... hmmmm...no dead shorts. Something is turned on by the PIC.

5V without chip, 4.48V with chip

Something's loading it down! Try disconnecting the motors? Try disconnecting and unsoldering stuff until you find the 'leak'. Maybe change your program a bit to make absolutely sure nothing is being driven for X seconds before something starts to happen.?.?

when i put my meter on the doide symbol (i have never used it before and dont know what it is), i get .324V without any power applied to the board (im assuming there isnt supposed to be)

Try this with the 'diode' symbol on the meter. Hook the meter up to a plain ol' diode, 1N4148, whatever you've got handy. Whatever the meter reads (within range of course) is what the forward voltage drop of the diode is and if the meter leads are connected correctly. The datasheets on the diode will tell you what the nominal values are. You can also use this function to correctly identify leads on a transistor.

[dragons_fire]

to be honest, when i said everything was soldered to the board, i really meant there a couple things soldered to the board... right now it has the regulator, the PIC, OSC, power switch, headers and i have a diode, resistor and cap on the MCLR pin.. they are connected exactly the way it says too in the march 2007 nuts and volts... mclr goes to the programmer, then there is a diode off of that, with a 4.7kohm resistor to dvv, and a 1uF cap to ground.

it gets so hot so quick, that i havent programmed anything into the pic yet, and because its a plcc, i cant really use my breadboard to try it...

im heading to work though, so if i get a chance, i may look at it some more to see if i can find any shorts on any pins, and make sure i have the mclr stuff on right..

[skimask]

I'll put money on the MCLR diode put in backwards.
Any takers for odds?