Pololu 8 servo controller

Hi all,

I've just received my pololu 8 servo controller card (RS-232 / DB9), but I didn't succed to do anything with.
I have a question concerning the jumpers on the card.

1) What should I do with the jumper DTR / RTS. I've read the user guide but I'm not sure to understand everything.
2) Same question with the jumper Mode. At the moment, I've removed the jumper. So it is normal mode.

Here is the link to the card : http://www.pololu.com/catalog/product/727

I've read the post of mboracing. So I think I did evething I should do with Force-sender and X-sim profiler.
The LED color of the card is yellow (normal ?).

I've set only 1 axis for the moment, with a vertical force. Everything seems to be ok with X-sim profiler. I try with GTR2, and I can see the value (verticla force) changing when I run the game, but the servo motor doesn't move.

Any help for me ? Please look at my questions 1) and 2).

Thanks
Adbgg

I give one more information...

The yellow LED of the card is flashing when I launch X-Sim, so I believed there is a data transmition between X-sim and the card. Then the LED stop flashing and the light keep yellow color.

I can't understand why the servo doesn't move, when the game is running.
Because all the values in X-sim (speed, gear, lateral and vertical forece, etc.) change when the game is running.

Any suggestion for helping me ?

Thanks

Adbgg

Maybe reading the controller's datasheet or manual will help. Make sure you are transmitting information that is expected by the pololu.

I did : I've read the user guide. But my english is not perfect, and also I'm a newbie in this kind of stuff.
However, I'm looking at many posts, and others website to try to understand, and to make it works (pololu card).
But still nothing. I have been trying for 2-3 weeks and I'm very disappointed for the moment.
So...I will look and try again and again, but I don't know what to do now.
Thanks
Adbgg

Have you tried it with the provided software? Is it only X-Sim that cannot move the servo? Troubleshoot piece by piece. Start with something that works, then work your way up.

Hello adbgg

First, as Frakk sayd, have you tested the card without x-sim and it works?
Second, please post some pictures of youre work. (the polulu with the cables and a screenshot of youre uso settings). Pictures say more than 1000 words ;D

Cheers, mbo

Edit: Open the jumper dts. Put the jumper for the mode in place (we use miniSCC Mode)

Many thanks for your reply !

The servo works with an other usb card (pololu USB micro maestro) ans his software. So the servo motor is not the problem.
The card RS-232 pololu 8 servo seems to work. Sometimes the yellow LED is flashing, that means the card receive data information. For example, when I run X-sim the yellow LED is flashing, and when I close X-sim the LED keep yellow but without flashing.

So I believed it is the configuration. Please have a look at the pictures here : http://picasaweb.google.com/104580337905152916967/XSim#

Concerning the pololu card. I've put out the jumper DTR/RTS, and placed the mode jumper in.
Servo motor is connected to n°0, battery 4,8V to the S/+/- and the battery 6V to the VIN/GND. SO nothing special to say.

Please have a look at the pictures, and perhaps you have already some comments or advices to give me. It would be kind of you.

Thanks
Adbgg

You should try it with this program.
http://www.pololu.com/docs/0J23

You have to Connect to the controller, so you probably need to send a start byte. Also note the resolution.

Thanks Frakk !

I've got this software. I've already downloaded it from the pololu website. But I didn't do anything with until now. Is there a configuration to do with this software ?

My question is : what do you mean by you probably need to send a start byte ? Could you precise the command line, and where I must fill in ? I've read the user guide. I didn't see anything concerning the start byte.

I've tested my servo motor with an other pololu card (micro maestro), and the resolution of my servo motor (the range) goes from 992 to 2000, when I use the software adapted to the micro maestro card. It is a software easier to use than the one of the pololu 8 servo controller.

The range is 992-2000 => Is that your question when you speak about resolution ?

My servo motor is a little servo from graupner, with a 180° range.

Thanks again for your advice. cu.

I never used these servo controllers, so I'm only suggesting these things. I don't know if you have to configure anything, maybe the Baudrate if it is not automatic when you Connect.

In that pololu program you see that Connect and Disconnect button? When you click these, the program sends the controller a command saying Hello, I am going to start transmitting data, so you better control those servos. When you Disconnect you're telling the controller I am done controlling the servos, you can go back to sleep now!

In the profiler above your Datapacket with axis information you can see: Datapacket sent at simulator start and Datapacket sent at simulator stop.
These will be your Connect and Disconnect commands. If the Serial utility doesn't show you the exact bytes in the Sent/Received data(hex): section, you can use a serial port monitor to analyze the data flow. Search this forum and google.

By resolution I mean how many bits of information you need to transmit for one axis. Profiler can transmit 8bits (0-255) , 16bits (0-65535) and 32bits. The controller will convert the received byte to the output pulse length needed for the servos 1ms - 2ms, so your OUTPUT resolution is 1us.
In the serial utility you can send bytes, which makes me think it will be an 8bit axis information.

As I said before, just go down to the basics and get it working with their software. You have to learn how to walk before you run.

OK, thanks for your advice.
I'm aware I'm still a newbie, but I progress every day. I want to make it works, so I thnak you for you comments, and I will read other posts, and I will try again, and again.
It is strange that it looks so easy, and in fact it is not.
Easy to move the servo with the pololu micro maestro card, and not so easy with the pololu serial transmitter. And more difficult to combine with X-sim.
Thanks again
cu
Adbgg

Hello adbgg

You give already a start byte; is the ~255~ at the start.
Try out with changing the 0 to an 8 (~255~~8~~a01~) As you can see in the Manual, 0 is in 90°, 8 in 180°. If you want you can send your rn file so i can give it a try.

For tests you can use the Testtablet, locatet into force sender aplication, so you dont have run a game for testing some values. Also for youre test please let the calibration offset of this axis in center, you can use it for fine adjusting later...

Cheers, mbo

Hi Mboracing !
Very kind of you.
As you proposed, I have sent you an email with my *rn file and some questions.
Again, many thanks for your help.
cu
Adbgg