RoboSavvy Forum

Parallax Propeller Controls Hexapod & New BS2 Motherboar

2007-01-04T14:00:41+01:00

I have writen from scrach the serial routines because the ones that are downloadable at Parallax do not work at 1Mb.

For now I am using the Parallax Demo Board. It exposes enough pins to start to work and have some nice features: video, keyboard, mouse, ... Now I am trying to accomodate a mini-TV display in the back of my current experimental robot. It is great to have a color TV to display all AX12 parameters on the fly!
It can be tested too with a naked Propeller or the Propstick. Wiring is absolutly simple.

The problem I have found is that Spin may be somewhat slow to achieve a tight closed loop control or for sending data to a PC. That is to say, the ASM serial code is fast enough but the Spin code is not as fast. I would like to have the high level routines writen in Spin. Perhaps a smarter buffering would help here.

I must say that it is a real pleasure to use the Propeller for robotics control. And also I must say that I love the serial interface of Robotis servos! Just thinking on those horrible servo controllers with plenty of used pins makes me laugh. I use only one pin to control my whole robot!

I am cleaning the code and documenting somewhat all the stuff. I will post it here when finished.

Statistics: Posted by inaki — Thu Jan 04, 2007 2:00 pm

Parallax Propeller Controls Hexapod & New BS2 Motherboar

2006-12-29T00:28:07+01:00

Please keep us updated on you progress using the propeller Inaki. I have been intrigued by the Propeller since it's release. I'm looking forward to seeing your progress and hopefully following in your footsteps!

- Marc

Statistics: Posted by NullARC — Fri Dec 29, 2006 12:28 am

Parallax Propeller Controls Hexapod & New BS2 Motherboar

2006-12-28T19:33:51+01:00

Inaki

You don't happen to have any Spin code I could play with do you please?

Mark

Statistics: Posted by pepperm — Thu Dec 28, 2006 7:33 pm

Parallax Propeller Controls Hexapod & New BS2 Motherboar

2006-12-29T07:11:28+01:00

I have selected precisely this chip for my own Bioloid controller board. It is an amazing micro and very nice for robotics. Of course the serial nature of Bioloid servos is a great way to save lots of I/O pins.
RAM is a little scarce however(32K for Spin programs, Spin is the high level language used in Propeller). I have been using FRAM chips to store external data but for certain purposes more internal RAM would be necessary. For certain tasks you need to use ASM instead of Spin because this one becomes too slow, although for most purposes it is fine. You can combine both Spin and ASM to perform critical tasks in ASM while keeping general code in Spin. For example you can use the ASM Fast Serial object to communicate with AX12 servos while keeping the logic of the code in Spin.

There is a strong community of Propeller fans that build very interesting new "objects" every day to support any kind of device.

Parallax has anounced a project for making a new Propeller with more RAM (128K), in the future but this may take some time to be released.

Statistics: Posted by inaki — Thu Dec 28, 2006 10:38 am

Parallax Propeller Controls Hexapod & New BS2 Motherboar

2006-12-26T09:42:51+01:00

Hi

Yes I have had a couple of Propeller chips for a few months now with the intention of using them with my Bioloid. It's a cracking chip (8 processors on one bit of silicon) with a great programming environment. Sadly I have been busy on other things since they arrived and not had much time to investigate the possibilities. But the Propeller is very very fast but I suspect suffers from not having enough memory for storage of things like motion files. I could be very very wrong though and I am sure external "serial" memory could be added if required.

I would encourage everyone who is interested to get hold of the Propeller development board and play with it. They are very cheap really and I think Parallax have recently dropped the price.

Mark

Statistics: Posted by pepperm — Tue Dec 26, 2006 9:42 am

Parallax Propeller Controls Hexapod & New BS2 Motherboar

2006-12-26T03:51:54+01:00

I saw this and thought it might be a viable option for making our bipeds more advanced, adding sensors, processing power etc. I think it would work great for bipeds that use standard PWM servos. I think with a little more effort it could be used to control the Dynamixel Bioloid servos. I know many people here are looking to make their robots more autonomous. Every new piece of equipment takes that much closer!

Here's the link: http://forums.parallax.com/forums/default.aspx?f=25&m=161756

Also I saw this new product from Parallax. It's a neat idea. It has 2 Atmel AVR processors for offloading computationally intense processes while keeping the programming of the BS2 easy. Daughter boards will be made available to easily handle interfacing, data acquisition, and sensing functions etc.

Here's the link: http://www.parallax.com/detail.asp?product_id=28300

Let me know what you guy's think about these. Seems pretty intersting!

- Marc

Statistics: Posted by NullARC — Tue Dec 26, 2006 3:51 am