TreadBot

[mackrackit]

I can not comment about the differences in the two chips.

Have you used this v-reg before? This is one part you may want to breadboard. I looked at the data sheet and did not see a minimum voltage, are you sure the batteries are charged. Try putting a known load on the v-reg and watch the output. Could be something wrong with the v-reg or cap size.

It still might be a good idea to build an adapter and bread board the PIC. Try another power supply.

Just looking back to basics. To many variables going straight to finished product.

[dragons_fire]

i just used my "power board" to power a 16f877A, the motor driver and both motors.. works good.. i would prefer to use teh 18f6585 because of # of I/O, memory size and speed..

i might just go back to using a 877A for now, just because i know i can work it..

i just dont know what else to do to get this 18f to work...

[skimask]

i just used my "power board" to power a 16f877A, the motor driver and both motors.. works good.. i would prefer to use teh 18f6585 because of # of I/O, memory size and speed.. i might just go back to using a 877A for now, just because i know i can work it..
i just dont know what else to do to get this 18f to work...

You've got a 6 cell NiMH (or NiCad, doesn't really matter). Open circuit, they've probably got 1.3-1.4v per cell when fully charged. You put a load on them, they'll probably drop down to, say, 1.1v per cell, maybe less. As I stated earlier, with a regular linear regulator, you need a certain amount of 'voltage overhead' to keep the regulator working correctly...usually about 2 volts. Anything less and your regulator basically freaks and starts outputting a lot less voltage.
So, you've got that 6 cell pack, roughly 6.6v under a load, more likely less since you're driving motors (50mA no-load doesn't mean squat when you're trying to drive this thing around).
Looking at that datasheet you linked to earlier (Page 11, Figure 11), you need at least 6.1v @ 1.5amps of load to keep the regulator happy.
Try this for grins... lift the Treadbot up so it's wheels can free spin, power it up and see what your voltage is.
I'm thinking that you're going to have to run an 8 cell pack of AAA's instead of 6 AA's.

[dragons_fire]

well, right now my power board works great with a 16f877a, the motor driver and the motors. (both motors togetehr are around 200mA at full speed). when im playing with the 18f6585, i dont have the motors, motor driver and all the other little stuff isnt hooked up. just the pic and an led!!! when i measure the resistance across the board, (with the PIC in) i get about 1 Mohm. input voltage is around 7.4 (fully charged cells). but ohms law says that 5V going through 1Mohm, there is almost no current... not a short... even when i hook my multimeter up, it shows no current.. but the voltage drops right down to around 2V

[mackrackit]

The PIC that is giving trouble is the same one that was in the boad with a short?

What is the exact part number of the PIC giving trouble? I will get one or two and try.

[skimask]

well, right now my power board works great with a 16f877a, the motor driver and the motors. (both motors togetehr are around 200mA at full speed). when im playing with the 18f6585, i dont have the motors, motor driver and all the other little stuff isnt hooked up. just the pic and an led!!! when i measure the resistance across the board, (with the PIC in) i get about 1 Mohm. input voltage is around 7.4 (fully charged cells). but ohms law says that 5V going through 1Mohm, there is almost no current... not a short... even when i hook my multimeter up, it shows no current.. but the voltage drops right down to around 2V

Ok, all notes noted....
You're using a '6585 now...
You didn't by chance get the pinouts between the TQFP and PLCC pinouts mixed up did you?

[dragons_fire]

yeah, i was trying to use a 6585... i did use the pLCC pinouts. i need to look into that some more though, cause i was thinking that maybe my pins dont match.. in expresspcb, when i click on a pin, it tels me the #, i think maybe its wrong, or it might be different than my socket, and that could be causing my problem..

nothing heats up anymore, i just lose voltage, and my "power" LED dims. maybe this PIC is shot from my mess up earlier, that its not allowing things to work now..

i put this project on hold for the weekend, im building a lightning trigger for my DSLR camera. sensor works great on the breadboard, im just trying to figure out my optoisolator to keep my circuit seperate from the camera... im using a 16F88 for this (i was going to use a SMT 12F675, but i have lots of room and lots of 88s).

im still thinking about my robot, so i didnt give up on it, so im open to any suggestions.. im trying to avoid making an adaptor to breadboard it first.

[Darrel Taylor]

Hey Dragon,

It appears that all the VDD and VSS on your PCB are backwards.

Here's a 68-PLCC socket and 18F6585 pinout

<table><tr><td valign=bottom></td><td valign=top></td></tr></table>

and here's your PCB

I haven't checked the rest of the pins.

HTH,

Added: Oops, and PIN 49 is VDD

AddedMore: No doubt the original chip is Fried.
<br>