Gumstix

[limor]

(moved from newbie thread)

Inaki wrote:

Gumstix uses a general purpose processor, the XScale by Intel. That one is an ARM compatible CPU, one of the so called 'System on Chip' processors, because the processor integrates a lot of peripherals. The good side of such a processor is that is is powerful enough to make a complete system. The bad side is that you must use a full fledged operating system to run it. That is to say, you cannot pretend to start this processor and start doing input/output to a digital pin for example, like you would do on a microcontroller. The Gumstix comes with a version of Linux. So it means everything you do must been done through this operating system. There are other operating system available in case you don't like Linux but then you should count on adapting the operating system to the Gumstix board which may be not a trivial task. This may be good or bad news for you, depending on your preferences and your ultimate goal.

For my taste sys on chips are somewhat overkill for domestic robots. Sys on chip processors may be interesting if you pretend to have a real computer on board rather than a controller board that is most suitable for microcontrollers.

Basic Stamps work very well as peripheral controllers. The problem with Basic Stamps is how to do many things at the same time. They are good for one or two tasks but no more. However you can add several Basic Stamps together to perform complex tasks. The best of BS is that are simple to program and have many peripherals already made for it.

For general purpose control I prefer PICs or AVRs. There are many microcontrollers out there, some of them very powerful, but having a common controller like a PIC or an AVR gives you more comfort when you have to do the real development: programing tools, libraries, thousand of available projects already made, documentation, ...
PICs and AVR are inexpensive for the power they give and you can use several on the same board.

For servos control the best choice is a separate controller that can be controller serially instead of relying on the processor direct control. A typical robot has 12 or more servos which is too much for some microcontrollers. Also note that microcontrollers share lines so if you reserve many pins for one task you lose lines for other tasks. There are dozens of them that you can adapt to your board of choice. For initial programming it is best to have a serial servo controller that you can plug to your PC.

The gumstix potentially gives your robot brain autonomy at a decent price and power consumption. It also has bluetooth for remote human control and potentiall further brain power from a desktop.

Actual servo control can be better done with boards containing processors that specialize in multiple A2D and servo control like oricom or newmicros and serial communications between them.

Kondo's RCB-1 board is also good if you use the Kondo ICS digital servos because it provides interface to the position feedback that can be used for advanced feedback control

[inaki]

I must clear up that I have not used Gumstix boards, but have used many XScale boards. The Gumstix seem to be more compact than other boards and has very accessible I/O pins. However it is still a computer on a chip and requires a much more complex implementation that youw would require using a microcontroller. For the same reason it gives a huge power to control a robot once it is implemented.

I am not against Gumstix or boards in that line. I think they are too much for most domestic robots.

For now I was not thinking on using a Gumstix but, as I am open minded, please, try to convince me of trying a Gumstix for the KHR !!! For starters, where can I place the board on the robot ?