I am trying to learn a bit about programmable circuits. I am a programmer so that side is a piece of cake, and have been learning how to build some basic circuits.

Anyhow does anyone know what the big differences are between the Basic Stamp and Pickaxe? Price wise there is a huge gap and I am really just wondering if the cheaper one is good for doing certain things and at what point you move into the more expensive vesrion.

The Prop-1 ($39.95) and Prop-2 ($99.95) from EFX-TEK are basic stamp controllers with support circuitry to allow interfacing to props directly. They would be the best to start with unless you are really good with electronics.

I have not ordered the Basic Stamp IC ($28) either - At that price it is better just to buy the Prop-1 from EFX-TEK.

I have been looking at the PICaxe ($3.95 for the 8 pin chip) recently due to it's price, but have not yet ordered one to play with. It requires a programming cable (So does the Prop-1&2) and of course the ULN chip to allow it to drive stuff.

__________________
- Brad

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Haunt at Red Clover
Parker, Colorado

I've done a LOT of picaxe programming, and can vouch for its abilities

Yes it does require a programming cable, but its a cable you can build yourself, and you get instructions on how to build the cable with the manuals

so basically ALL you need to do to get started with the Picaxe is buy it, the software is free, the programming cable is free, for a chip that you can get up and running with for $5 then what are you waiting for?

Are you looking for a controller or a PLC? I have used the Basic Stamp in the past to learn about different controllers and also used another program to try and use a PLC.

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Money won't buy you happiness, but it will buy me another case of beer

Thanks for the pointers guys. I am about as cheap as it comes when building things. So I think Picaxe is the way to start. At $5 anyone can be willing to mess around enough with it to learn and not feel bad if you end up breaking it.

The project I have in mind is that I am looking to make a control panel for my alien autopsey table. The panel would have about a dozen or so LEDs in which I want to make the LEDs light randomly for a certain amount of time. Maybe expand upon in the future so that they all flash when an event occurs.

You wont be controlling a dozen LEDs with an 8 pin Picaxe as it only has 4 output pins, but programming the 08M Picaxe is exactly the same as the rest of the Picaxe family, you just have to take case which options you try and use as not all chips are teh same

Make sure you get some 10K and 22K resistors for building the programming interface, if you have an old serial mouse then you can cut the cable from that and use it as a programming cable.

I ordered a PICAXE08M a few days ago to experiment with.

By the time you add the cost of the PCB, voltage regulator and other required parts you are at the cost of the Prop-1.

I downloaded the free software for the PICAXE and I do like it, the simulate mode is really cool, It allows you to turn the inputs on and off and set the analog input values then you can watch the program run and see if you have made any mistakes.

When the chip gets here, I'll prototype the circuit and see if everything works. Then I can run a total on the parts required for this type of prop controller.

My plan is to have two pots one set the entry delay time the other with set the on time for the prop. The other two pins, one will be the trigger input and the other will drive a relay to control the prop.

Here is the program:

#picaxe 08m
let dirs = %00010001 ' switch pin 4 to output
let pins = %00010001 ' switch on output4 4

main:
readadc 1,b1 ' read value into b1
readadc 2,b2 ' read value into b2
if pin3 = 1 then gobaby ' wait for trigger
goto main ' cycle if no trigger

gobaby:
let w1 = b1 * 35 ' calculate input delay time
pause w1 ' wait for input 1 delay time
high 4 ' prop on
let w2 = b2 * 35 ' calculate prop on time
pause w2 ' wait for input 2 time on time
low 4 ' switch prop off
goto main ' return to waiting for trigger

__________________
- Brad

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Haunt at Red Clover
Parker, Colorado

It seems that the downside of a build your own is that you could damage components and could have some extensive troubleshooting. The upside seems that by doing this you gain knowledge on the inner workings of your circuit. You also gain flexibility. This is a debate I am always up against in my day job. Custom app versus third-party.

So is prebuilt always going to be the cheapest solution? If you got the 40 pin picaxe controller, would you have just as much expansion as the Prop-2 Controller? Would the picaxe solution become more cost effective at this point or would the extra components for the extra pins still weigh in heavy?

When setting up to do something new its always going to cost a little more but once you have the kit under your belt and understand whats essential then you are on the road to having the ability to do things cheaper.

The voltage regulator is not a required component, its often a good idea, but by no means essential.

PCB?? do you mean strip board? or is this a development PCB you are buying? I prefer to prototyping using breadboard, and then moving onto strip board... if PCBs are required then you are entering a new world of expense, and they only pay when you have a quantity in mind.

I recieved my PICAXE08M and built the attached ciruit around it.

It seems to work pretty well, and programming was pretty easy.

J3 is the trigger input, I designed it to work off of 12V instead of 5, to keep false triggers to a minimum, the only problem is that the transistor inverts the input so the program has to be written to activate with a low instead of a high.

R9 sets the delay from when the trigger is detected to when the prop fires.

R10 sets how long the prop stays on.

There are two outputs, output 0 turns on as soon as the trigger is detected and turns off when when the time set by R10 expires. The second output turns on after the delay time set by R9 has expired and then turns off when the time set by R10 expires.

My idea is that output 0 will turn on an MP3 player, while output 4 turns on the prop. I attempted to make this generic to allow it to be used on most of the props I build each year.

Here is the code that I put in the PICAXE08M:

#picaxe 08m
let dirs = %00010001 ' switch pin 0 and 4 to outputs
let pins = %00010001 ' switch on output 0 and 4

main:
readadc 1,b1 ' read value into b1
readadc 2,b2 ' read value into b2
if pin3 = 1 then gobaby ' wait for trigger
goto main ' cycle if no trigger

gobaby:
high 0 ' turn on output 0
let w1 = b1 * 35 ' calculate input delay time
pause w1 ' wait for input 1 delay time
high 4 ' prop on (output 4)
let w2 = b2 * 35 ' calculate prop on time
pause w2 ' wait for input 2 time on time
low 4 ' Turn off output 4
low 0 ' Turn off output 0
goto main ' return to waiting for trigger

This code is very similar to the code that the Prop-1 and Prop-2 use, so it was very easy to move from writing code for a Prop-1 to writing code for a PICAXE.

I am still unsure how much the controller will wind up costing, I will keep you guys updated.

Attached Images

controller.jpg (81.0 KB, 20 views)

__________________
- Brad

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Haunt at Red Clover
Parker, Colorado