Compared to other microcontrollers i have seen the vex microcontroller seems pretty pricey. an atmaga168 is only a few dollars. The Arduino and basic stamp are both less and they appear to have more flexibility.
A little story…
A decade ago, I worked as a Contractor, at a Large Microchip Manufacture. One of the Regular Employees had previously worked for a Company that had written some Computer Software, that was licensed for $125,000.00 (USD). It fit on one little 5.25" floppy disk (the type of floppy disks used before the 3.5" ones) that cost maybe $2.00 (USD).
Why the Very Large Price?? It was Banking Software, that calculated Exchange Rates of foreign Currency’s.
The cost of an Item (The Vex Controller for instance) is not always the Cost of the Parts.
Would you hand your ATMega168 and a Development board to a 6 year old along with some sensors and Motors and tell them to “put it together”??
The Vex Controller is just about “Bullet Proof”. You can’t plug it in wrong, nor Static Damage it, or Short it Out.
Also the Vex Controller is really Two Microprocessors, the Master and the User. You can only re-programmer the User Processor. The Master Processor is always in control. This is needed for Maintaining Control during a Competition. The ATMega168 or Basic Stamps does not need this level of Master Control.
ok that makes more sense now
I didn’t know the part about the master and user sections of the controller. That’s interesting.
It is vulnerable to static damage, I think, a lot of the robots that I’ve worked on will build up a large static charge on the VEX field. These robots also tend to have a lot of “control” issues.
Otherwise though it is pretty indestructible.
I guess I should rephrase that…
Static can cause permanent damage to Bare Circuit Boards. The Vex Controller seems very well protected against that type of Damage.
Static causing operational issues is another matter.
Thanks… I try real hard…
Where I work, we take Standard Parts, and Add Value by “Engineering Solutions” with them. The Majority of the Cost is the Engineering and the Labor of assembling them, not the Parts themselves or the Profit for the company.
The Official VEX Technical Support FAQs are a very good read.
Read through the VEX Microcontroller FAQs:
You can start with Master / User processor.
The IFI Vex Controller uses two Microchip PIC18F8520 controllers along with the protective circuitry mentioned by MarkO and the plastic enclosure and terminals and leds that complete the controller assembly. The firmware is highly optimized marvel of software engineering designed by IFI that includes most of the functionality necessary to build and control modern robots and devices. I find it very useful for rapid prototyping my own designs and controlling them with Easy C 2.0.
The Vex Controller is faster and has more memory (SRAM) and more on-chip peripherals than the Parallax Stamp BS2/BSX/BSP controller. The Easy C or PIC18C is faster since it is compiled directly to assembly rather than interpreted as is done in PBASIC. I still find Stamps very useful for getting hardware to work since they are so easy to connect and program with PBASIC, thus making them a good choice for prototyping and testing electronic circuits.
By upgrading the Vex Controller with the PWM adapter cables it becomes a true DC motor controller with Quadrature Encoder inputs that could be used to point a telescope at a star and track it across the sky using Easy C to program it. My modified “Shelby” version of the Vexplorer shown in the Vex Gallery uses the Vex Controller to make it “programmable”. I have been able to add Vex sensors and limit switches and bumper switches to it and extra motors to turn the sensor platform.
The majority of the price is not in the components, all of those components together would probably run you about $25, it’s in the labor and proprietary licensing. VEX is a big name, they run an international competition, and they have a huge product line that is all compatible with each other simply, so they charge that high price for the simplicity. Not to mention, it takes a lot of work to get a system that works so well together. A lot of these parts have been made from scratch by them. Those gears are custom molded, along with most of the other plastic parts in the kit, all the metal is custom-punched, and the entire default code library was written by IFI, and simplifies dealing with the dual-processor architecture greatly.
That high price doesn’t make it the best tool for your job, it just makes it a good tool for a lot of jobs. For example, my Seeeduino Mega (Arduino variant) has 4 times the program memory, 3 more TTL ports, over 5 times the number of interrupts, 4 times the RAM, 3 times the number of PWM capable ports, 48 of any of the pins can be run as servo outputs, 70 total I/O pins, including 16 10-bit analog inputs, I2C, SPI, USB, and the list goes on.
The Arduino code is nice an simplified, however there’s still a LOT to manage with all of that. And all of those 70 I/O pins are in single headers, they don’t come in that nice 3-wire interface on the VEX, so anything new you want to do, you have to break out a breadboard. Not to mention, timing things gets hairy because you do only have the one processor. Whereas the VEX has some functions tell the master processor what to do (like all of the Servo outputs, unless otherwise specified using the default code, not in EasyC or RobotC), the Seeeduino has to do everything all on one processor, and there’s not really an easy way to interface any kind of radio control without tricky timing and/or writing your own protocol.
So to sum up, you’re paying for the license, the compatibility, and the engineering that went into development. Overall, it’s worth it if you have the money and the interest. But it’s also worth it to also buy a few other things to play around with for other projects that are better suited, like the ATmega chips. It’s all about what’s better suited for your project.
I believe I stated something similar to this… Thanks for the Second Opinion…
Vex makes sense for getting a project up and running… A lot of the Heavy Lifting is done for you, but with that Speed of getting going quickly, you sacrifice some flexability. Lucklly there is more and more options out there, at a very reasonable cost… Seriously, there has never been a better time to get into Robotics… And the Vex is an EXCELLENT place to start…