SOUT,SIN,ATN And VSS Pins

Twisted Pair

Do·the 1,2,3 and 4 pins need any thing connected to them if·a pre-programmed·Basic Stamp module is installed on a prototype board ?


Thanks, Twisted Pair....·

Nick Waldvogel

As long as it's preprogramed and you won't want to change it when it's installed, you don't need them.

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Twisted Pair

I'm having a little trouble with my encoder after moving it from the BOE to a prototype board and didn't know if this was a related problem even after reading all the documentation about the BOE and the module. Thanks Nick....

Twisted Pair....

Chris Savage

What sort of problems are you having?

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Chris Savage
Parallax Tech Support

Twisted Pair

Hello Chris. (Solder Pot Controller Circuit). It's the Encoder again. When pressing the set button, the set temperature goes wild as shown on the display. If you remember, I had this same problem when I moved the circuit from the BOE to the Super carrier Board. I thought that I had found the problem in a cold solder joint, But that wasn't it. So I moved the circuit to my prototype board, made a power supply like on the BOE schematics and connected all hardware involved. Same result regarding the wild set temperature. When you hold the set button down, the set temperature goes from where ever it happened to fall at the time, (random), to the max temperature set in the code. If you turn the encoder knob back one click, the temperature will go all the way down to the minimum temperature set in the code. I have checked all my connections for continuity (ok), and against the schematics (ok). I have also checked the 10k pull up resistors for the encoder (ok). I have checked things over a thousand times but I'm missing something. The only thing that I can think of at this point is that instead of using a LM2940CT Voltage regulator like on the BOE in my power supply, I used a 7805 Regulator, thinking that there is a difference between these two regulators that is causing the current to vary enough so that the 10k pull up resistors are of incorrect value now. I also was thinking that pins 1-4 needed a pull up or pull down resistor or capacitor or something even though my module was already pre-programmed on the BOE and all the documentation that I read said other wise. I just had to ask about the pins here in this post. It seems like I have tried everything but I haven't found the problem yet. There is something different between the BOE and my prototype board and power supply etc. I have been going back and fourth between the BOE and my prototype board with the circuit, and all works on the BOE but when back on the prototype board all is working except the encoder. I'm still looking for the problem with earnest. No luck yet.

Thank you Chris

Twisted Pair....

Chris Savage

TP,

You said you checked the A/B outputs of the encoder…But what about the Common (C) line? If your encoder outputs are pulled-high (active low) then the common line should be going to ground. Is this the case? I still believe the issue is in the encoder circuit. As for the power supply, the 7805 is a perfectly suitable regulator. Of course, if your supply is noisy you could be having issues. You should have the proper capacitors on the input and output of the regulator. The 7805 doesn’t have a specific requirement so you would adjust those for your supply and load conditions. Again, I would revisit the encoder…Are you sure you’re connected to the correct pins on the encoder? Do you have a picture of it?

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Chris Savage
Parallax Tech Support

Twisted Pair

Yes, the A & B are connected properly and the Common goes to ground. I have two 1000mF caps. One on the output of the regulator and the other on pin 21 (Vdd) of the module. I would have to charge up the batterys on my camera for a picture but for now, Pin A of the encoder is going to Pin P0 on the module and Pin B of the encoder is going to Pin P1 on the module while the Com is going to ground. I have all the components (Led, Buzzer, Set Switch and Display etc) mounted on one prototype board while another prototype board has the module and power supply on it. When switching the circuit from the prototype board to the BOE, I just plug the wiring from the proto board with the components on it, into the correct sockets on the BOE. And of coarse I use the module from the prototype board on the BOE when switching from one to the other. I agree with you that it's in the encoder circuit but I must mention how I'm powering the circuit. I copied the BOE board regulator schematics trying to keep everything the same as the BOE as all worked on that board. I send power into the board regulator by means of a wall transformer. Parallax PN# 750-00009, 7.5 VDC, 1 Amp, which is the same power supply I use on the BOE when using this circuit. Again, I tried keeping everything the same between these two boards simply because it works on the BOE....

Thank you Chris

Twisted Pair....

Bruce Bates

Twisted Pair -

Am I correct in saying that there is only one power supply for all of this?

Am I also correct in saying that all grounds come back to the same (approximate) place and are tied together to the power supply ground (- terminal)?

Regards,

Bruce Bates

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Twisted Pair

Hi Bruce, There is a wall transformer (7.5vdc @ 1amp) that plugs into the BOE that has an on-board regulator that steps the voltage down to 5 volts.

Yes, you are correct, all grounds are close to each other and are all tied to the BOE's on-board regulator ground pin....

It should be noted that the Vin on the module is used instead of Vdd Pin....

Thanks Bruce....

Twisted Pair

Here is the Schematic for the BOE....

Twisted Pair

Here is a picture of the Encoder connections Chris.

Thank you Chris....

Twisted Pair

Here is a schematic of how I'm powering the·module and it's components. Notice that the wall transformer is 7.5 Vdc @ 1 amp going in to the Vin pin of the module and the output of the 7805 Voltage Regulator is 5 Vdc that connects to all the Vdd connections which includes the Encoder (My Problem Area). Could the voltage difference between (Vin) and (Vdd) be related to my Encoder instability even though the (Vin) going in to the module is regulated down to 5 Volts by the modules on-board regulator ? It appears·that the two 10K resistors connected to the Encoders A & B lines are not pulling·up pins P0 & P1 on the module. I have checked all the wiring, connections and wiring schematics. All are Ok.

Thanks for your help

Twisted Pair....


Post Edited (Twisted Pair) : 6/17/2007 8:38:42 PM GMT

Chris Savage

I’m going to assume you don’t have the V_DD from the BASIC Stamp connected to the others…You don’t need that capacitor on there…That is used on the BOE for BOE-Bots to prevent a brown out during servo loads. Just to double check, the encoder was working on the original board, correct?

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Chris Savage
Parallax Tech Support

Twisted Pair

Vdd from the Stamp is connected to the C1 capacitor only. Vdd from the 7805 voltage regulator connects to all other components (Temp Set Button, Buzzer, Heat Indicator Led, Power on Led, SSR and the Encoder). The Stamp is getting the 7.5 Vdc (Vin) and the components get the 5 Vdc from the 7805 (Vdd). Everything is working on the prototype board except the Encoder. When all is put back on the BOE board, everything works, including the Encoder. The prototype board is wired and set up the same as the BOE board with the exception of the 7805 voltage regulator. I figured the large capacitor on the Vdd pin of the Stamp was for the servo load, but I put it in anyway.

Chris Savage

This is a stretch, but since the circuit works on your BOE and it’s unlikely the 7805 has anything to do with it, I can’t help but wonder if your board (looks like a Radio Shack unit) is the problem? Here’s what I mean. Often larger breadboards will have a break in the bus strips used for power/ground. So the two long strips that go across the top and bottom quite often are not connected in the middle. I don’t see any jumper wires on your board to account for this if it is the case so I now believe it could be a possibility. We have the same thing on our PDB, which is why the documentation for the PDB (see page 4) shows how to connect these. Hopefully it’s something simple like that. Take care.

http://www.parallax.com/dl/docs/prod/boards/ParallaxPDB.PDF

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Chris Savage
Parallax Tech Support

Twisted Pair

My prototype board has the jumpers in place. I have checked for all the obvious things and so far I see no mistakes. I've attached a schematic of how things are connected. Maybe this will help.

Thank you Chris....

Post Edited (Twisted Pair) : 6/18/2007 7:18:18 PM GMT

Chris Savage

Okay, since this issue is specific to this board (works on the BOE) I don’t know what else to suggest. Seems specific to the board. I know these things can make you lose hair.

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Chris Savage
Parallax Tech Support

Twisted Pair

Ok Chris, I will keep looking and pulling hair.

Post Edited (Twisted Pair) : 6/18/2007 4:55:48 PM GMT

Twisted Pair

Ok, Problem Resolved....It was the Breadboard....As mentioned in the previous posts, all the voltages, connections and continuity checks proved ok, yet the Encoder did not work. This Breadboard was almost new and was never abused. It was checked serveral times during my endeavor and checked ok with no load applied. During my troubleshooting phase, I noticed that the spring connectors, down inside the Breadboard, was making contact on the side of the IC module pins rather than on the flat sides (more contact area), like the Parallax sockets do. This partial contact at the IC pins where the Encoder connects, is why I was having a problem.

Twisted Pair....

Chris Savage

Glad you got it figured out. Take care.

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Chris Savage
Parallax Tech Support