can someone help me check?

[saturnX]

I was wondering if i could get feedback from you guys. Attached are 3 files:

1. Schematics of the robot
2. My connections on the breadboard with the motor cable plugged in
2. My Connections without the motor cable

I only had 1 motor plugged in to test the circuit if it was working and the end result was that the motor jerked (i think that's the word) a little then nothing happened. the codes is based on the one the i posted in MeLabs PICBasic thread/discussion. If you could help me it would be great.

i am concered about the diode connection. can't really see it in the picture but currently the silver band is facing away from positive terminal but it heats up. is that normal for it to heat up? is it possible that i might have the wrong diode type?

if you could help it is much appreciated

[mister_e]

The use of a diode to reduce the voltage is not the best solution if the target circuit don't need much current. In this case, the voltage drop on the diode will be less than what you wish.

SO, your PIC is probably dead now and short. This is why your DIODE comes HOT.

You should double check your crystal connection also.

What is between the PIC and the Motor?

[saturnX]

do you know how glad i am to see your nick online on the forum! is there a manual way of testing if the chip is dead? i don't get you on the part of the where you asked whats between the motor and the chip. If i get you correctly there isnt anything except a link to RB0 from the chip to the motor. Remember the codes i posted on the other discussion where u helped me convert to basic. yeah that is the codes and the schematics are attached here.

you reckon i should get a batch of fresh new chips? oh the other question which i forgot to mentioned (maybe i did) in the first post, is there a difference in the type of chip it uses. In the book it says 16F84 but when i got this batch from the robot store where they sold the parts to make this robot, they sent the 16F84A chip.

[mister_e]

OK now we have two reason to believe that the PIC is dead now. As the motor need more than 25 mA, you blow the I/O and the PIC. You MUST use a driver (MOSFET, Transistor) to drive your Motor.

There's not really a manual way to Test if the Chip is good or bad BUT, try to erase it and reprogram it again. There's lot of chance that you'll get some error message from your programmer software.

[mister_e]

16F84 or 16F84A... the one you have is a newer version. There's no big difference. But if you want to have the truth, there's probably some Migration document or errata on this chip on the Microchip website.

[saturnX]

i just so happen to have just erased and reprogramed it but i didn't get any errors when it was doin so. i even got it to verify the burn to the chip and it came back OK including the blank check.

when i disconnect and reconnect back the diode the motor jumps to life for 1 second then nothing.. the diode heats up from there. but have a look at the original schematics from the book (attached drawing.jpg) the author did not include any transistors in between the chip and motors.

[mister_e]

Yeah i see but you must have it. As your pin is probably dead, try with another i/o it will work for a few, then blow again.

Do you have any spec of the motor you use?

Do you have some Npn, PNP transistor or mosfet on hand? If so wich ?

Double and triple check your Crystal and capacitor connection...

[saturnX]

no i don't have any at hand right now. the electronic shop is 5mins from my house. i want to ask about the crystal and capacitor connections... have a look at this website schematics: http://home.planet.nl/~j.havinga/servo/servo.htm
how come the crystal is and capacitors are only hooked up to pin 15 where as in my book it says it has to be connected to both 15 and 16. can share some light on this?

servo motor: HiTEC HS-322HD (recommended by the author)
Class: Standard
Digital: No
Programmable: No
Voltage: 4.8v or 6.0v
General Specs:
- Bearings: bushing
- Gears: Karbonite
- 60° speed: .19 sec @ 4.8v
- 60° speed: .15 sec @ 6.0v
- Torque: 42.00 oz/in @ 4.8v
- Torque: 51.00 oz/in @ 6.0v
-- 1.57 x.79x1.46 inches
- 1.52 ounces


In the book the author incorporated the diode to keep the power at least consistent at around 5.3v to make it possible to run the motors.

[mister_e]

ARGH forget me, i didn't notice it was a ServoMotor. So the i/o current is not a problem now.

While i don't see the same thing as you about the only one pin connection... it is connected on 15 and 16.

BTW, do something. Remove both capacitor, crystal and their jumpers, and sit the crystal directly on pin 15 and 16. It will work without the cap... on bread board only.

Next thing, did you set the osc mode to HS in your programmer software???

[saturnX]

i am using epic programmer to program the chip. are you familiar with that? umm if not explain to me "osc mode to HS" so i can find it and change it...



found it... but what is HS mode?

[saturnX]

the good news is that the diode is not heating up.. the bad news is that the "servo motor" doesn't move until i break the diode connection and reconnect it back. even so its a small little jerk then nothing else.

[mister_e]

no i'm not familiar with EPIC. BUT place the following line on the top of your code. It will set the HS mode for you.

@ __config _HS_OSC & _WDT_OFF & _PWRTE_ON

more info on the following link. Pay attention on #1 and #5
http://www.picbasic.co.uk/forum/showthread.php?t=543

i'm over for tonight.. good night and good luck!

[saturnX]

thanks for the help steve... guess i'm on my own for now. only 4 more hours to my presentation of this project. i am going to die! lolz!

[Luciano]

thanks for the help steve... guess i'm on my own for now. only 4 more hours to my presentation of this project. i am going to die! lolz!

I am so sorry to hear that!

After all this hard work in the previous three days you must be exhausted!
(Three threads in three days).

Stay home, don't go to school.


Luciano

[saturnX]

hi Luciano, i guess there is so only so much one person can do even with the help of the best. i just never understood why it didn't want to work. thanks for dropping by and the support. anything you can help me wif i welcome if with open arms

[Melanie]

Hi Andrew

You've probably missed your deadline... that's what happens when you do your project the night before. You gotta cut down on beer and girls...

In answer to your email... (not in any particular order)...

They wire Power Stations using thinner wire!

Get some single-strand insulated solid conductor wire - kinda fits into breadboards easy!

The way you got the Diode in your picture is correct. If things are heating up as you say in your email, then you have a major problem... you might have killed your PIC. If so, DON'T replace it with another F84... see my comment further down.

Can't see too clearly as your pics aren't that focused, but I think you've MISSWIRED your crystal. It also should have SHORT leads to your PIC... as short as possible. In future use a three-pin Resonator (one with built-in Capacitors) as it's easier to play with and breadboard - or use a PIC with a built-in oscillator. Depending on your breadboard, you might even be able to dispense with the Capacitors.

I HATE schematics out of books, they always omit things as the author assumes the reader has a basic knowledge... take a 100nF Capacitor between Vss (5) and Vdd (14) on your PIC... it'll kill any noise. Along with it connect a 10uF Capacitor (to smooth any supply irregularities) the same way.

You don't need the RESET Switch to make things work. It should fly as soon as you apply power.

The 16F84A is for all intents and purposes the same as the 16F84.

In future, get yourself a 16F628 or 16F628A... cheaper than an F84 and more fun... (you can make those work without Xtals or Resonators)... as well as being fully compatible with the F84's (with just one line of code difference).

See the Breadboard picture I've included. yes, I've used a F628, but you can pretend it's an F84. The salient points are keeping the xtal and capacitor paths SHORT... that's why I've got Vss running across the top rather than your Vdd. I've connecetd an LED between Vdd and RB0 (shorter lead of LED to RB0) via a 330R resistor (use anything in the range 220R-390R). I have a 100nF capacitor between the PICs Vss and Vdd, and a 10uF electrolytic similarly. Finally, the PIC doesn't draw a great deal of current, and consequentially the Diode may not drop 0.6/0.7v across it (another reason for hating schematics out of books). I've added a 1K resistor between Vss and Vdd to force a few mA through it. Either way, you're flying close to the 5.5v maximum limit of an F84A.

Put that LED and Resistor per my example temporarily (in place of your Servo) and run the appended code. It should blink once per second (half second ON, half second OFF - this assumes you have a 4MHz Xtal). If it does, you are in business, it it doesn't you have a problem.

    @ DEVICE pic16F84A, XT_OSC
    @ DEVICE pic16F84A, WDT_ON
    @ DEVICE pic16F84A, PWRT_ON
    LED var PortB.0
    TRISA=%00000000
    TRISB=%00000000
Loop:
    High LED
    Pause 500
    Low LED
    Pause 500
    Goto Loop
    end

Try to keep things on the forum in furture.

Melanie

[saturnX]

hi melanie!

i will try your method of going about the whole wiring and placement of components on the board and post my results later on tonite (now since i know how to take proper snap shots of the board). have to go dig out my LED's. hehe. oh just wondering the language you're using? is it basic stamp? i don't recognise it really and i tried certain codes which were written that way and the compiler didn't recognise it. I'm using PICBasic Pro for compiler, Microcode as editor and Epic Programmer to burn to the chip. But your way of coding seems a lot more easier. this is the one i have for PICBASIC PRO. does the same thing but differently.

'PicBasic Pro codes
Loop:
    High PORTB.0
    Low PORTB.1
    Pause 500
    Low PORTB.0
    High PORTB.1
    Pause 500
    Goto Loop

[Melanie]

I am using PICBasic Pro in my example (this is a MeLabs compiler site after all!). That example WILL compile with the command line...

pbp -p16F84A Filename

All I did was alias PortB.0 to LED, and use LED thereafter... applying this to your example...

    @ DEVICE pic16F84A, XT_OSC
    @ DEVICE pic16F84A, WDT_ON
    @ DEVICE pic16F84A, PWRT_ON
    LED var PortB.0
    AntiLED var PortB.1
    TRISA=%00000000
    TRISB=%00000000
Loop:
    High LED
    Low AntiLED
    Pause 500
    Low LED
    High AntiLED
    Pause 500
    Goto Loop

of course you can always simplify the whole (original) loop...

Loop:
    Toggle LED
    Pause 500
    Goto Loop

Aliasing you will find in your PBP manual. TRISA/TRISB you will find in the PICs Datasheet, and @ DEVICE you will find here...

http://www.picbasic.co.uk/forum/showthread.php?t=543