Let's Make Robots!

The Robot Builder's R-duino

June 24th, 2011.

I've been asked if I can make a board similar with the Robot Builder's Shield that also has the microcontroller on board and is compatible with regular Arduino shields. Not an easy task to do if I want to keep it with through hole components, but it's a challenge.

So I have designed a first prototype of the Robot Builder's Arduino R-duino. Features:

  • same size as a regular Arduino board, with 3 mounting holes
  • 6 servo connectors (power from battery, digital pins 8-13), 
  • 6 sensor connectors (regulated 5V, all analog pins), 
  • a SN754410 H-bridge (1 amp per motor, digital pins 4-7, uses Timer0 for PWM),
  • screw connectors for motors
  • pins 2 and 3 (external interrupts) available for encoders,
  • a FTDI connector (to program the board using a USB-serial cable),
  • a ISP connector (to program the board using a hardware prorgammer),
  • polarized Molex connector for the battery (4.5-12V, no more than 6V if you use servos),
  • reset button,
  • pin D13 LED,
  • power LED,
  • power switch,
  • 1A LDO voltage regulator,
  • all Arduino female pins are doubled with male pins, arranged to allow easy prototyping shields,
  • filtering caps near the sensor and servo 3 pin connectors.

J1 is to select power to the servos. J2 and J3 allow motor control mode, either 2 pin (Enable High, one Dir for PWM and the other for direction) or 3 pin mode (PWM on Enable, 2 direction pins). In 3 pin mode, 2 I/O pins allocated for servos are routed to the motors, so you end up with 4 servo connectors available. The LED on D13 has no selecting jumper, so it will flicker when a servo is connected to the same pin.

One more thing, the board does not have a 3.3V regulator, so even though the 3.3V pins are in place, they are not connected to anything and do not provide power for other shields. I don't think I can cram in a TO92 regulator in there...

Here is a picture, the blue is the bottom, GND plane, the red is the top, 5V plane. Round pins are male, oval pins are female. 

If you click on the pictures will bring a (latest edited) higher resolution version.

Let me know what you think!


September 13th, 2011:

I was told that the Arduino name is trademarked and can't be used on a product without approval and pay a license fee. So, I have re-named the board the Robot Builder's R-duino and I will order new boards with the new name, take new pictures and change the docs. Until it is all done, I can't sell any kits. Apologies to the Arduino team and thanks for understanding.


June 27th, 2011:

Updated the pictures after changing the 1A LDO regulator with the 3A LDO regulator. This is the final change before ordering the boards.


July 26th, 2011:

I got the boards from SeeedStudio in the mail today. They are a bit thinner than the boards from PCBcart and have white silk screen. Other than that, I think they look great. Here they are:

I got 12 boards and half of them were e-tested. From the ones that were not tested, I soldered all the parts so you can see how it looks like:

To test out the board, I have mounted it on my LMR Start Here Robot:


The only shield I have is a Color LCD Shield V2.0 from nuelectronics.com. I plugged it on the board to see if it fits and if the sensors and servos connectors can be accessible. The servo connectors are a bit tight to plug and half of the sensor connectors are covered by the shield. That may not matter much, as the shield uses pins D8, D9, D10, D11, D13 and A0, so only the pin D12 is available for servo use, but I can do a IR sensor sweep and print it on the LCD. The motor pins are unaffected by this shield.


I haven't programmed the board yet, that will be done tomorrow with some tests to see if all works properly.


Update Aug. 7th, 2011:

It seems that somehow I messed up with the SparkFun's FTDI connector and not swapped the Rx and Tx pins. For the first batch of 10 boards, the customers will receive a free adapter that swaps the pins. Then you can program the board and everything works fine.

Video of it in action comming soon.

Oh, the Robot Builder's R-duino kit is in the store!


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Wow, that board is packed!

A jumper option (you know I love options) to run the servo power from the 5V regulator, so you can run the motors from a battery higher than 6V and still use servos, would be lovely.

Speaking of jumpers, what does jumper J1 do?

I cannot read the schematic, it is too small. Can you post it as a file in a larger size?

I'm fairly sure I see a reset button, though you didn't list it in the features.

I uploaded larger files but they got reduced. I'll do it again and uncheck the reducing thing.

The reset button is included in the features, probably you missed it.

J1 enables power to motors and servos, I may use it just for servos, add a GND pin, so you have the option to use the jumper to select Vin to the servo connectors or plug a separate battery or uBec to power the servos. Not enough space to cram in a 5V-6V selector for servos, but I might use this jumper like that if you think is more usefull.

Forgot to mention, there are 4 more jumpers to select the control mode for the motors, just like in the V3 of the Shield, either 2 pin or 3 pin (with PWM on the Enable). If one chooses 3 pin mode, 2 servo pins will be used for motor control (D8, D9), so there will be only 4 servo pins available (D10-D13). Also, the D13 LED has no jumper, so when a servo is used on D13, the LED will flicker. If you need the LED, you will have only 3 servo connectors available (D10-D12).

If I'll get the part for that 4 pin LDO v-reg, I'll use that, since it will be enough to power the servos from the regulated 5V.

Anything else I missed?

You can attach the larger files and then link them to the inline pictures so that if you click the picture it takes you to the larger file.

Just did it while you were typing...

While I can't comment on the board / electronics desgin side of things,  I certainly like the look of what you have designed.  I have a couple of projects on the go for which that board would be an excellent fit.

I can't wait to see where this goes / i'd love to get my hands on one  :-)




This is a very nice board with a lot of options that makes it good not only for small robots but also for robot experiments.


Thanks! It looks like there will be people interested in this board. I'll order 10 pieces and sell them as kits or just the PCB.

Details where I can purchase this? Perfect for robot building!

I am ordering 10 boards at SeeedStudio, will be here after 3-4 weeks, then you can order. I was still looking into adding a 3.3V regulator on board and change the 1A LDO for the 3A one before I send the order.

The boards are in! Soon in the store, after I do some tests.