Can you further explain on the two capacitors? I am a little confuse.

Silo89

Hello,

I am new to this forum. And not to long ago I adquired a Javelin stamp. I have read the manual and re-typed the sample code for the firts exercise "ButtonLed",
and finally I ran into this post on this forum.
I have the Javelin, and I am confuse about these two capicitors. I am aware about the two capacitor on the Javelin demo (C2 and C3)·and I have ran continuity test from this capacitors to the serial pins 4 and 5, and to the the ATN and VSS and they appeared to be connected.

Now, is there anything else I need to solder, attach or wire in order for the javelin to work. The update to the manual, which adds the capacitors in the diagram, is that something we physically have to do, or is it just to have·correct documentation.

I have the correct power supply, I ordered from Parallax.
I am able to connect and download the programs, but they will not execute.
I am aware of the the new wiring update to this diagram.


Please advise, I am confuse and·unpatient to get this thing working.

Thank You

Chris Savage

Hello,

·· Do the programs run if you unplug the Serial Cable and press the RESET button on the Demo Board?

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Chris Savage
Parallax Tech Support
csavage@parallax.com

Silo89

Unfortunately no, the first program I am trying to execute is the ButtonLED on page 26 and no luck. If I press the button to make the LED blink nothing happens.
- I have tested the LED’s (with a multimeter Diode tester and they light up)
- The button works correctly when I press it; the continuity test indicates that it closes.
- I have tried pressing the reset button.
- I can successfully run the “Test Connection” and “Identify” command from the “Project” menu.
- I can press the “Compile” button with no errors, I can then press the “Program” button, then a “Javelin Terminal” windows appears stating:
“Window, and enter a command” I am assuming the program was downloaded, but when I try to press the button to make the LED blink nothing happens.
I have press the reset button on the board; I have unplugged the serial cable from the board and nothing.
I have tried the red and green LED’s and nothing.

According to the manual, this should be a straight forward procedure, but I may be missing something. I would like your guidance, since I would like to further dive into the Javelin and its other fun projects and that’s why I am a little inpatient.

Thank you, I will be standing by for your reply.

Sincerly,

Silo89

allanlane5

Please post your program, it sounds like you have other problems.

The purpose of those capacitors: The Javelin IDE uses the DTR signal (becomes ATN) to reset the module just before it downloads the new program.

Now, if you hook up Hyperterm (or some other 'generic' serial port TTY program) it tends to hold the DTR signal HIGH. When the DTR signal is HIGH, it holds the module in RESET -- UNLESS you have those two capacitors there.

With the two capacitors, when Hyperterm pulls DTR high, the ATN signal goes high briefly (which resets the module) and the caps then let the ATN signal go to ground, so the Javelin can run.

Silo89

The program I am posting is copied and pasted from the Javelin> Examples> Manual_v1_0 folder.
I first tried to type it mey self, but since I had problems, I figure I should just open the examples provided compile it and download it to the Javelin. I am running version 2.0.3 of the Javelin copiler


// Program Listing 2.3 - Flash LED with Pushbutton

import stamp.core.*;

public class ButtonLED {

static boolean P0 = true;

public static void main() {

while(true) {
if (CPU.readPin(CPU.pins) == false) { // If button pressed
P0 = !P0; // Negate P0
CPU.writePin(CPU.pins[noparse][[/noparse]0],P0); // LED [noparse][[/noparse]On]
CPU.delay(1000);
} // end if
else {
CPU.writePin(CPU.pins[noparse][[/noparse]0],true); // LED [noparse][[/noparse]Off]
} // end else
} // end while
} // end main
} // end class declaration


In advance I want to thank you for your time and patience. I feel some relief knowing that these forums exists.

Silo89

Can somebody provide me with some guidance? Can someone share some knowledge or experience. Any tips will be greatly appreciated.

allanlane5

I think your problem lies in the "if (CPU.readPin(CPU.pins) == false) " statement.

I think you need to modify CPU.pins to check for a SINGLE pin -- right now it looks like you're reading all the pins, which will always be true, unless you have them all grounded...

Javalin

Hi,
With reguard to your two capacitors, i've found from painfull (and expensive experience) that if you use the diagram in the V1 of the manual (like BS2 connections) the comms part of the javalin gets fried.· If this is the case perhaps the nice people at parallax will repair/exchange it for you.· For experimenting with buy a BOE (board of education) from Parallax, its the best way to learn!

With any thing new, go slow and keep it simple.· By rushing and jumping I've fried many chips!!

I think the example apps are installed with the Compiler, somewhere in C:\program files\parallax\javalin.· I cannot remember the exact path. (hence you dont have to type them in...)

Once you have working hardware:

while(true) 
{ 
    if (CPU.readPin(CPU.pin1) == false) 
    { 
        // If button pressed 
        CPU.writePin(CPU.pin2, true); // LED [noparse][[/noparse]On] 
        CPU.delay(1000); 
    } 
    else 
    { 
    CPU.writePin(CPU.pin2,false); // LED [noparse][[/noparse]Off] 
    } 
}

Im doing this from memory, you'll have to correct any typo's in commands etc. You'll also have to change the CPU.pinX to the correct pins.

Good luck - keep at it. The javalin really is the best stamp!!

Post Edited (Javalin) : 9/13/2005 2:10:31 PM GMT