µServotino robot controller

Let's Make Robots
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In November 2010 I have started the design of a new piece of hardware, the µServotino. Much like it's brother µBotino, this board is 2x2" in size (5x5cm), has a voltage regulator, switch, ISP connector, FTDI connector, 6 sensor connectors (GND, 5V, Signal) and 12 servo connectors (GND, Vin, Signal). There is also a UART connector (with associate 5V and GND pins) in case one wants to hook up a serial device to the robot. Plenty of filtering capacitors and 2 LEDs, one for power and the other for pin D13, that can be disabled by removing the J1 jumper. This time I used a  Screw terminal connector for the battery, because it is rated for higher amperage than the keyed connector and the servos will draw a lot while moving under load.

I placed an order online at iTead Studios on December 4th 2010 and I asked for yellow color boards, to be in tone with the uBotino and the RBS. The boards were fabricated in a few days and shipped after about one week from placing the order. I have waited and waited... On Jan 6th 2011, the package was returned to sender from the Shenszen customs. iTead Studio wrote me an email explaining that Canada Post did not pick up the parcel. WTF? They shipped the package again, using Hong Kong post and today (Feb 4th 2011) I picked it up from the post office. Finally. But, to my surprise, the boards are green! WTF? Of course, the colored boards cost more... Oh well, I wrote them an email to see what can be done to correct the error. Until I get a response, I don't really want to start soldering... But the boards look great, good quality.

I will place the schematic, PCB layout and pictures of the actual boards tomorrow, I am too tired right now. I have a bitter taste from this experience, although it's not completely iTead Studio's fault. But still, green boards instead of yellow? If they were not sure how to make them, why not ask?

Back tomorrow guys...

 

OK, here are the pictures,

Schematic:

uServotinoSCH_resize.jpg

PCB layout:

uServotinoBRD.jpg

the µServotino, front and back:

uServotino_005_resize.jpg

And with the µBotino:

uServotino_004_resize.jpg

Latter I'll uplod a picture of the assembled board.

 

Ok, here it is:

uServotino.jpg
uServotino.jpg461×500 69.4 KB

And here's what you can do with it:

uServotino_020_resize.jpg

Tests after I upload the bootloader...

2

Man, I like your stuff

That’s it.

I like your designs, use of space, simplicity while still getting all the bells and whistles out of a board… Good stuff.

Yet another one out of the park.

I am still using your “regular” shield on a daily basis. It has become my “standard” “trying something out” test-bed.

3

Thanks Chris!Did I send you

Any beta testers for the µServotino?

4

Thanks Chris!Did I send you

Thanks Chris!

Did I send you a version 2 shield?

I also promissed one (v2 shield) to somebody else but totally forgot who. Stupid me… Please remind me, whoever you are…

5

Could be me. I reviewed your

Could be me. I reviewed your V1 shield and found the trace that needed to be cut to get it working.

I’d be very interested in reviewing the uBotino and uServotino.

6

Cool

Sweet X! So this will drive up to 12 servos eh!! Please let me know when you have this released. :wink:

7

This is making me keen

to get my own board made. Just have to overcome my impatience for using(searching) the parts libraries in eagle. Very nice work R-B-X.

8

Happy to beta test for you.

Happy to beta test for you.

9

Successfully assmebled the

Successfully assmebled the uServotino kit. The pre-installed ‘blink’ program works fine. I need to build an FTDI cable so I can program it. I plan to use this tip by Ro-Bot-X to build it. the cable is already on order.

I’ll post a review soon!

10

You have made some very nice

You have made some very nice Arduino based boards!

Beeing far from you I could not buy one but I have build my own, finally. Not as complete as yours, just the basic circuitry for ATmega328, two LED’s and their resistors, a whole lot of headers and my own communication header.

11

Thanks cr0c0! You just have

Thanks cr0c0! You just have to drop me a PM if you need something. I have send 5 boards of the uBotino and the RBS to the RoboFun.ro store, but they can’t buy from a self employed person, so I am looking to spread them around. I offered some of them as prizes in their local competitions (look at Tehnorama.ro). If you want one, I’ll ask Viorel to send it to you.

12

Glad the board finaly is in

Glad the board finaly is in working condition. I guess you managed the crystal problem, that will be corrected in the next batch. Now I need to know if you have problems programming using the FTDI cable. On the board I assembled, the 10k pull up resistor shows up like 7.2K and the board does not autoreset. I have to press the Reset button manually to make it upload. I did not had time to further investigate the problem, as latelly I didn’t do any work on robotics. So I’m curious if it’s just my board like that or all boards are.

13

OK. I just finished building

OK. I just finished building the programming cable you described.  I get the same result you did. I had to hit the reset button in order for the sketch to load.

14

Thanks! I will revise the

Thanks! I will revise the board design to find out where the bug hides and crush it merciless! Also fix the crystal & caps issue. So it’s good the board is not yellow, green is the way to go for the beta versions.

15

After months of gathering

After months of gathering dust, it was time to get the µServotino up and running. Before I put it into a hard to reach enclosure, I had to find out what was going on with the autoreset malfunction. I started measuring traces with my DMM and to my surprise, I found out that the capacitor that is supposed to be connected in series from the DTR pin of the FTDI cable to the Reset pin of the microcontroller “seemed” unconnected. I took an empty board and scraped the paint off and the traces are interrupted close to the capacitor pads. Not sure if it was my fault or manufacturer’s (some time ago I edited the design and moved around that capacitor, so I can’t say for sure it was unconnected), this is easily fixable. When you solder the capacitor, don’t cut the leads too close, leave them about 1/8" (3mm) long. After you solder the Reset button and the FTDI header, bend the capacitor leads one to touch the Reset button and the other to touch the closest pin of the FTDI header and solder them toghether, making a bridge. If you have your board alredy soldered, use 2 pieces of wire to replace the broken traces. That’s all it takes for this little board to work as intended.

16

That must be satisfying.

Like eliminating an itch you had forgotten you had.

I’ll have to mod my uServotino when I get a chance. Thanks for updating.