Servo Micro Controller to ATMEGA 644


Im looking through your forums as we speak to see if i can find solution. I purchased the Micro Serial Servo Controller and I thought I had it working correctly, sending bytes off the AVR did cause the Servos to move correctly.

Now we are nearing the dead line of our project and I am starting to run into trouble.

I am currently using the STK500 AVR Eval Board and when I tried to send 3 bytes to the Controller it would not respond, at most the servos would flutter to a non-specific location then the green led would remain solid while the red led would flash.

So I looked at the web site and downloaded the Serial Transmitter Utility. When I send 3 bytes to the controller via the COM I.e:

0xFF,0x08 (180 mode),0xFE then 0xFF, 0x08, 0x00

the servo would move around 1/4th to the position then move again till the position was reached. Then it gets worse every time I send the same exact bytes it will flutter to another location… as though it was lost in the process.

I plan to implement servo motors on to robotic arms where I will run two servos one on the Elbow and one on the Shoulder of one arm.

I state this because I also get the problem of the servo reaching the desired location and not Holding that position. The arm raises then falls flat. The arms are made of light wooden dowels.
I currently have the jumper bridging the the power to the servo and the micro-controller on the controller
Thanks for your help and I will be on this post till I find some similar forum.
Is there some kind of start up sequence of bytes I should send first? Via Mini SSC-II mode.

Also I would like have a link explaining in great detail the Pololu mode. The Data Sheet it comes with is not that clear. I understand sending 5~6 bytes and the cmd to do so but It does not explain much about the Data1 Data2 Byte with each cmd, or I’m confusing my self.


Everything Is running at 5V

Ugh Sorry wanted to make it more clear:

5V Micro Servo,
When Testing it off the AVR I use the Logic level in Pin

When Testing it off the COM I use Pin 3 Logic out Serial Data to RS-232 pint

Mental Notes:

Just found One nice thread… for any one reading this… will check this out tomorrow

ReEdit everything, Yeah sorry Reading more about Pololu Mode, would like to learn more,

Mental Note:

"Pololu Micro Serial Servo Controller" not working //will try separate DC power supply … (-.-:wink:

More I read the more it sounds like power issue… And will attach the 4.7k Ohm resistor… WIll test tomorrow
Almost Positive its power issue… I was testing LCD, Micro, Pololu Cont., Xbee, Logic Level Converter… all off the STK500 Eval board PWR/GND Header pins

Ok Quick Update.

I am now using a septate power supply to the Servo pins (6V with 2A at no load)

and connected the VTG/GND header pins off the STK500 to the micro controller pins. Now when I send the bytes off the COM channel using the Transmitter it goes to the Starting Position but when I send more bytes it does not respond… It just stays put.

For Example I send bytes:

0xFF 0x00 0xFE / 0xFF 0x08 0xFE … it stay put… Ive sent variations of the code…

I have connected a Jumper from Pin 3 of COM to the rs-232 Pin and Pin 5 ground to GND pin beside the rs-232

I see the Green Light Flash when i send Bytes and All the LEDs are off and I set the Baud to 9600

Is there something im over looking?


Ok… Im very sorry…

Let this be a lesson to people who dont read data sheets…

Read on a forum to do 0x80/ 0x02/ 0x08 to read the amount of LEDs flickering… Kinda got lost my self.

Read the Data Sheet and reprogrammed the servo numbers to lol 200 something…

Reprogrammed to respond to 0-F servo numbers…

Everything Works lika Charm

VIVA Pololu!!!


I’m glad you got your servo controller working! Was your problem with your power or with your serial commands? Let us know if you have any other questions.

- Ryan

It was the Power. My team member the previous day questioned that I may not be providing enough power to the Servo pins I just blew him off on accident cause its what I do lol.

Man did he enjoy rubbing my face in it.

I will definitely come to you guys if I run into any more problems.

Thank you guys.