Need help with certain part for a robot.

[Aidis]

Hello everyone , i have been working some time on a project to make a robot using a mini-itx motherboard and an RC car. The problem i have encountered is how to control the car motor using a port from the itx (USB/Serial/LPT?) I am a electronics newbie but willing to learn given the proper documentation , i just need a push in the right direction , i was thinking either using the USB power output to control the car or a battery and then use a circuit to open/close the power flow depending on the output of the serial or lpt port ... Any ideas?

 

[Aidis]

Maybe a circuit that would turn on , turn off and invert the flow of power of the battery to the motor using the COM port?

 

[tansis]

I would recomend using the parallel port as a wealth of information can be found on the web. Circuits abound and the software is easy enough.

Just one question springs to mind at the momemt though..
how big a battery do you need to power that motherboard?

 

[Aidis]

Aha. What kind of circuit board would i search for , for the kind of thing i need? Well i have seen other Mini-ITX robots , and since laptops run only at 16 - 24 VDC .. I dont think it needs to be THAT big ( ? ). LPT sounds about right.

 

[Aidis]

Just found out, EPIA Mini-ITX motherboards have a 12 DC input converter. So i guess battery size wont be such a problem ...

 

[Aidis]

Since LPT in high state ( 1 ) is +5V can for example 2 of the cables power a 9/10V motor?

 

[Nigel Goodwin]

Since LPT in high state ( 1 ) is +5V can for example 2 of the cables power a 9/10V motor?

NO! - you can't (or at least you shouldn't!) power anything from a parallel port, it should only feed to suitable buffers and drivers.

In any case, two 5V outputs is still 5V, it's the current which is increased.

It's VERY easy to damage your parallel port, and as most are now integrated in the motherboard, this then requires a new motherboard.

If you don't know what you are doing, and fully understand the reasons for doing things, I would strongly advise against blindly experimenting with a parallel port!.

 

[checkmate]

1. A mini-ITX board seems overkill for motor control unless you are implementing some state-of-the-art control system. Usually, microcontrollers are good enough.
2. RS232/USB are for data comms between microprocessors/fpgas, not for control purposes. You'll need general I/O pins and AD/DA for control.
3. Parallel ports are meant to provide signals, and not power. Same applies to serial port, LAN etc. USB does provide limited power, but nowhere capable of running a moderately sized motor. These signals may be used to activate MOSFETs or relays for power control.
4. Motor control is usually carried out via H-Bridges. They are somewhat functionally equivalent to what you shoed in your post.

No offence, but you seem a long way from what you are trying to achieve as the options you provide dont really make alot of electronic sense. Try reading up on some basic electronic theory first, and maybe some info on microcontrollers.

 

[Aidis]

Heh , its true i am a software programmer not a hardware guy , the reason i need a mini-itx is because the car is going to be controled via WLAN , and fitted with a camera and again going to have some basic AI (Maybe with some IR sensors ( ? )). I can do the PC-Parts , the hard part (for me), and main reason im here is how to control the motor from the motherboard. I know , softwarely , how to send data , and set high/low values on various ports. H-Bridges , ill look that up. It is possible though right?

 

[Aidis]

Looked it up , there are H-Bridges controled by pc i/o ports though , right ..?

 

[Aidis]

I found a relay that might work at this site. https://www.epanorama.net/circuits/parallel_output.html , the first symatic , use 1 pin for each command? (Forward / Backwards)

 

[MrMikey83]

If you're look at a single speed, w/ forward and reverse, you can use relays if thats easier for you. But if you want to pulse the motor output to control the speed, relays usually aren't fast enough and an H-Bridge is to be used.
Sounds like a cool remote control car project. So you'll be able to control it from any computer in the world. I've seen other projects like this but usually they are on a site where anyone can control it and you have to wait your turn...I'm not that patient, heh
~Mike

 

[Aidis]

Ok i found the parts and im going for the assembly .. a few questions..

1. Were does the battery input OTHER cable go?
2. On the 1N4148 , does the side with the black line mark mean thats the N or P side?
3. Is this circuit ok or will it blow up?

Thanks!