Society of Robots - Robot Forum

Electronics => Electronics => Topic started by: dunk on February 10, 2007, 06:23:04 AM

Title: USB servo controller
Post by: dunk on February 10, 2007, 06:23:04 AM

so i have finally got round to documenting one of my projects.
it's a USB servo controller.
so, i'm looking for comments about the quality of the documentation.

i'm afraid it's not a particularly "beginner friendly" application this time round but i'd appreciate it if anyone with some experience with AVR microcontrlollers and Linux could take a look through and see if it makes sense. (or build one!)

it all makes sense to me but then, i wrote it. i'm looking to see if someone else could follow my instructions.

if anyone with experience writing windows or Mac software is interested in writing a windows or Mac controll program for it that would be great too! while i use only Linux i appreciate that most people don't.

i posted it in Admin's new "member written tutorials" section.
link:http://www.societyofrobots.com/member_tutorials/node/23 (http://www.societyofrobots.com/member_tutorials/node/23)

dunk.

Title: Re: USB servo controller
Post by: hgordon on February 10, 2007, 10:23:06 AM

Has this circuit been tested ?  I would not expect you to be able to interface directly from the USB connector to the microcontroller without a USB <=> UART bridge chip such as Silicon Labs CP2102 or FTDI FT232, but I'm not familiar with the MEGA8 processor - perhaps it already have this functionality built in.

Title: Re: USB servo controller
Post by: dunk on February 10, 2007, 11:07:55 AM

Quote

Has this circuit been tested ?

yup. it works realy well.
so for the USB communication i went with a firmware only solution:
http://www.obdev.at/products/avrusb/index.html (http://www.obdev.at/products/avrusb/index.html)

dunk.

Title: Re: USB servo controller
Post by: hgordon on February 10, 2007, 11:35:06 AM

Very nice !  I had not seen this before.

Title: Re: USB servo controller
Post by: alexm0428 on April 21, 2009, 11:08:19 AM

Hi.

I'm new, and I was looking for exactly this. Great work.

As I told I'm new on this world, and I had a little question.

The USB servo controller can "write" the Atmega8? I mean, in the firmware part, you have to download the program with a different programmer, or you can use the "USB servo controller". If not would you recommend me a programmer that works with this project without modifing anything?

Thanks a lot.

Title: Re: USB servo controller
Post by: SmAsH on April 21, 2009, 04:42:37 PM

hwere did you find this topic... its more than 2 years old...two years...

Title: Re: USB servo controller
Post by: dunk on April 22, 2009, 03:09:33 AM

hi Alexm,
yes, the Atmega8 is a single chip computer or "microcontroller".
you need a programmer to upload the firmware to the Atmega8.

there are tutorials online on how to do this but to be honest the USB servo controller is probably a bit too complicated as a first microcontroller project.

try reading the $50 robot project on this website for an idea of how to work with microcontrollers. http://www.societyofrobots.com/step_by_step_robot.shtml (http://www.societyofrobots.com/step_by_step_robot.shtml)

alternatively there are devices for sale that allow you to control servos from a computer.


dunk.

Title: Re: USB servo controller
Post by: alexm0428 on April 22, 2009, 08:33:24 AM

Well, I'm not to "beginner". I allready worked a little with micros, (the motorola family).

I'm really new at the linux world, that's way i didn't get if you could program with the same servo controller, or you need a programmer. But you just answer it so thanks a lot.

I wiil look for a suitable programmer. I mean one i don't need to change anything of the code, because there is where I don't understand how. (I mean on linux). If you could help here too, it will be very helpful.

Thank you.

Title: Re: USB servo controller
Post by: dunk on April 22, 2009, 09:08:13 AM

there's a tutorial here on programming AVRs from Linux:
http://www.instructables.com/id/Ghetto-Programming:-Getting-started-with-AVR-micro/ (http://www.instructables.com/id/Ghetto-Programming:-Getting-started-with-AVR-micro/)

dunk.

Title: Re: USB servo controller
Post by: alexm0428 on April 24, 2009, 08:51:02 AM

Tahnks.

I'll give it a try.

Title: Re: USB servo controller
Post by: alexm0428 on April 29, 2009, 04:14:37 PM

Hi. Another question.

I know I can deduce the answer by reading the code, but I don't want to miss understand.

The question is: When you read the angle (status function) you actually "ask" the servo the position, or you look in some kind of memory of the servo's moves.

Thanks

Title: Re: USB servo controller
Post by: SmAsH on May 04, 2009, 12:40:26 AM

you send a pulse to the servo and it moves to that place...
i would think the easiest way to read the angle would to see the last place moved to.
there may be a way to read the pot's angle but i haven't heard of it...

Title: Re: USB servo controller
Post by: alexm0428 on May 04, 2009, 06:07:45 PM

Quote from: SmAsH on May 04, 2009, 12:40:26 AM

there may be a way to read the pot's angle but i haven't heard of it...

That's why I am wondering about how the instruction works. I was trying to undertand the code but I got confused...

Thankyou for your reply