Moving a resistor for EvalBot power when programming

[Riley Porter] posted a picture of his EvalBot USB power hack. In the photo above we’ve put a box around D6 and D7. The development board ships with a 0 Ohm resistor in the D7 location, patching in power from the USB-B connector labeled USB DEVICE. He found that by moving that resistor to D6 he can power the board from the USB-B connector labeled ICDI.

That connector is the In-Circuit Debug Interface. TI sent us an EvalBot bundle so we pulled it out and tried it ourselves. If you plug in the ICDI it doesn’t power the board, and no USB devices register. Shorting the D6 pads changes this and the following USB device registers:

Bus 002 Device 062: ID 0403:bcd9 Future Technology Devices International, Ltd Stellaris Evaluation Board

So it looks like you need to have two USB connections or be using batteries in order to program the board via USB. The uC/OS-III hardcover book that ships with the EvalBot bundle includes board schematics. We took a look and were surprised to see that they show diodes installed on both pads. Rev A of the online schematics have been corrected, showing an omitted diode on D6 and the 0 Ohm resistor on D7. Images of both schematics are included after the break.

It would have been nice to see a selector switch installed here to give you a little more flexibility when prototyping.

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EvalBot: arrival and assembly

[Chris Muncy] just received his EvalBot from TI and took some pictures of the assembly process. He was one of the lucky folks that picked up the kit for just $25 using a short-lived coupon code. Seeing the kit makes us wish we had ordered one. There is some assembly required but as you can see, it’s pretty much just mechanical assembly of the wheels and the front bumper arms.

We think the wheel design is quite good. It consists of two small gearhead motors mounted on the rectangular PCB parts that you can see on the right portion of the image above. Those mount to the circular mainboard using metal L brackets. The wheels themselves are three circular pieces of PCB, one with a smaller diameter sandwiched in between its two larger cousins. This creates a channel that is perfect for a neoprene O-ring to give the wheel traction. The main board uses an optical sensors and a hole through all three parts to function as a rotation counter.

It’s a fancy piece of hardware and we can’t wait to see what you can do with it! If you’ve got one, we want to hear about your adventures.

$125 off the Evalbot is a steal

When you see $125 off something you probably assume it cost several times that to start with. Nope, this drastic discount leaves just $25 plus shipping. Use coupon-code: 2JLP-R4XRT3 when ordering the little rover. There’s a quick video snippet of it embedded after the break.

What you’ll get is a Stellaris ARM Cortex-M3 microcontroller on a board with a bunch of goodies.

  • MicroSD slot
  • USB host and device connectors
  • I2C audio with speakers
  • Ethernet connector
  • 96×6 OLED display
  • Motors
  • Optosensors
  • Bump detectors

As always, we want to hear about the hacks you come up with once you have this little guy in hand.

[update, the code is now expired]

[final update -- Someone from TI explains what is going on.]

—-  from the comments.

As some posts already note, the coupon code is only available to ESC Boston attendees. That said, we’re psyched about all of your interest and understand there seems to have been some confusion, so TI plans to fulfill all of the finalized orders to date. We’re working on some logistics in getting the code up and running again for ESC Boston attendees, but proof of ESC registration will be required. Stay tuned.

We hear you about the e-store and are working as quickly as possible to avoid issues in the future. Thanks for your patience.

Bottom line – we’re glad to see the excitement around EVALBOT and look forward to checking out your projects! We encourage you to share them on our e2e Forums at http://e2e.ti.com/

-Jean Anne Booth, Texas Instruments

——-

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