Let's Make Robots!

Picaxe 28A only works on board

Hi guys. This is very strange, really. And since it is very strange i must have forgot to do something very simple....

 Anyways this is my problem: i got a 28A picaxe, programmed to do a "high 5, low 4". That's all. I connect my picaxe chip on my 28 pin board (the one i also use for my picaxe 28x1) and everything works fine (LED lights up). I take it out, put it in my custom board, and it doesn't work. Now, my "custom board" is not more than a 28 pin IC-socket which has every pin connected to a male header and the download circuit, the battery is connected directly to the V+ pin and so is the ground(V0 pin just under it). This is quite strange.... don't ask me if i have checked the connections, i checked them ten times already!

Have any ideas? 

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i realize it may not be the same chip, but still....http://www.lasertag.de/pics/circuit1.gif 15 pFs used for this one :) (in case someone else needs this)

does anybody know if that way of interfacing the resonator works with picaxe? (the one in the link) I see nothing wrong with it, but you know just to be sure... 

you can usually enter the part number in google and find some pretty detailed information about them.
had no luck with that...

i thought about building my own board because, as hootyhoo said, it's fun and interesting to actually learn about the components you are using and understand why you are using them. Not only, by making it i have improved my soldering skills, which were kind of poor (much better now, but still in the process of learning). And of course you can customize it anyway you want, for example i have added a male header for every pin on the picaxe so that i can easily bypass all those connections they go through on the picaxe board, and can easily interface it with a breadboard, and have also added 7 pins for V+ and 7 for V0.

 I really suggest everyone to make one! And by the way...i'll be reading allaboutcircuits.com, i am really frustrated to see circuits work not knowing why (eg: why does a 4.7k resistor goes there? etc...) 


Thank you everybody for the feedback! 

today i went to some local electronics store. I bought a ceramic resonator and looks like the circuit is working as it should, how happy i am! Only one thing: i don't know if it has built-in capacitors. Those guys at the electronics store didn't even know what resonators were, i had to show them they actually had them in stock, so imagine if I asked them if those resonators had built-in caps -_- ..... they are standard 3-pin resonators like those on the picaxe board (by standard i mean...their design is standard). So what is gonna happen if they have no capacitors? To my guess, the resonator would heat up, but i have had the circuit running for some 2 minutes and it's not heating up... guess it's fine.




The device will either not function, or may have the frequency off a bit. If it works, and you still have serial communicaitons with the device, you are probably ok. The caps just serve as a feedback, to give the a steadying "bounce".  There mey be a few tech notes about them using the search terms Colpitts or crystal oscillator

This is the sort of thing most people don't bother to learn when using those prefabricated boards like the one used in "how to make your first robot". They are great to start out on to get a handle on how to program, but you don't really learn anything about how the circuit works.

My hat is off to you for creating your own board and gaining actual knowledge about the hardware. I know most of the people here are new and the "how to make your first robot" tutorial is a great place to start, but I hope that more of them will endeavor to branch out and start making their own circuits and learning how and why they work.

Isn't that the point....that you're starting out... :) You don't just jump to trigonometry just because you've learned how to add and subtract....

There is a natural progression in this hobby that you will get to a point where you'll need to know a certain amount of how the electronics work to be able to go further. At that point, the interenet is a great place....


edit- fixed typo

That's why I said that they're great to start out on.  Using a prefab board eliminates most of the frustration of not being able to get it to work.  After you've gotten it to work and learned how to program, the next progression is to start building your own circuits.  I am seeing people having trouble interfacing PICAXEs with the more advanced stuff because they haven't yet taken the time to figure out the basic circuits work.

thank you :) oh and about the capacitors do you have any suggestion as to their capacitance? I really don't know which calculations i need to do in order to understand that.

 oh wait the crystals i have seen only have two pins not three as you said... 

Resonators can have 3 pins, and sometimes have internal caps as well so you don't have add any. The data for the PIC should have recommendations on what device to use.