Society of Robots - Robot Forum
General Misc => Misc => Topic started by: blackheart on February 05, 2009, 03:17:14 PM
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Hey. I just found that I am deeply interested in robots few hours ago and I though I would introduce myself first! I am from Romania, a tribal organization, more likely where I can't find any boards, micro controller, etc. So before I order some online from an actual country in the 21st century, I have to start with my 10 RC cars back in transistor's age, far far away from IC's(enough of that). Note they are not modern cars like the savages from HPI. They are cheap $30 cars bought from stores like WalMart(although, bootlegged walmart) or stolen from my little brother! I opened 7 of them, to find some small boards. All I found that looks close to a Micro Controller is soldered and it has a sticker on it saying 27 MHz. Now, that makes me think it's a Radio Receiver. Question 1) What is it?
Other questions) I will take the risk of getting flamed, but I am not at home and the internet connection really sucks(I think it's still Dial-UP). I DID NOT google, hence my question. Do micro controllers in general have special sdk's ? The instruction set? How can it be programmed to compute information from photoresistors? Is it a matter of measuring the voltage?
I am interested more in the programming aspect of robotics. I am familiar with high level programming like C, even higher, java and python, and just a little bit of dirty assembly. But I've never gone deeper than assembly. I am trying kernel programming as I think that would help me cross the threshold towards embedded and hardware programming. I am not so much into resistors, capacitors, diodes, etc, but I don't mind! Not everything in life is pleasant, huh? I know the 50$ robot would be a good start for me, but I can not get the supplies for a reasonable price. I would have to pay too much for shipping...and I would if I knew I really used them and it would help me. But I am not sure.
Until then, Is there anything I can do with my RC cars? Some mods, or anything that would help me learn more about robotics?
Thank you for your understanding(or lack of...) and I can't wait to get familiar to this community. Until then. I'll hold my breath!
Cheers!
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answer to question 1: the microcontroller with a sticker on it with 27 MHz means that the microcontroller works at the frequency on its internal clock.
answer to other RC car question: if you want to play around with your circuit in the RC cars, unsolder it all and then put it bag together and see how it fits and practice soldering. this really helps. see if you can reverse something in the car controller (not the reverse polarity switch) so that all of the controls are inverse.
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Unfortunately you cant program any of the stuff you have - generally RC toys have purpose built microcontrollers that are not programmable. The $50 robot can be modified so that it's cheaper - instead of using servos, you can use one of your RCs as a platform.
The microcontroller measures the voltage of the input (photoresistor) and converts it to digital (ADC or analog to digital converter).
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Thank you both! Now it makes sense. I was thinking that 27MHz was the radio frequency. Thank you! Price isn't the main problem with the 50$ robot. I can afford to spend around $100 right now. The problem is getting my hand on the parts. I will see what I can do! I would so like to see the code that is used on the RC car. I think it would help me.
Do you guys have any piece of simple code that I can look at for the AVR or ARM? I would prefer if it was in C, not pseudocode, pascal or asm. Just some sample code that lights up an LED for example.
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27mhz is the radio frequency - not sure what the microcontroller is at.
Download the $50 robot source code, since you are experienced in programming it should be a breeze to understand.
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this is getting very confusing ??? sometimes it is radio frequency and sometimes it is microcontroller clock frequency. took a guess :D doesn't it usually say the radio frequency on the frequency crystal, though?
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The crystal might be inside the case (he said sticker was on the case). Anyways why would the manufacturer put a sticker that says the MCU frequency? Noone really needs to know.
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no, he said the sticker was on the micocontroller
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The sticker was on a small rectangle black piece of plastic like material. It looked exactly like the AVR ATmega8, but smaller and it's soldered. I already looked at the source code, thank you. It seems that it all comes down to voltage, opening/closing circuits, ports, etc. It is also very nice coded, imo. I think I will have to order the parts from england or somewhere close. Robots are too damn cool.
Thank you guys for all the help! I will be back
/me heads off to the MCU on the RC car. I am going to cut it and see what's inside.
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You aren't gonna see something useful unless you know how to cut it and have a electronic microscope.... :P.....
27MHz is the radio frequency....
The carrier frequency to be accurate... Probably these things use AM transmitter and receiver...
It's not something you are gonna use with this form...
the 50$ robot is a very good start!!!
and I don't really think you are gonna have problem finding parts....
There must be even small suppliers for electronics around Europe....
Best Regards, Lefteris
Greece