PDA

View Full Version : Controlling DC servo motor using FPGA



varungenius2001
07-10-2006, 09:26 AM
Hello friends,

I am new to robotics field. I am pursuing a PG Diploma course in VLSI/Embedded. I have chosen a robotics project.

Its Controlling DC servo motor using SPARTAN II, 2s200, DSP protoboard kit.

I require a level shifter circuitry. The output from the quadrature encoder is sent to the kit. But some of the data coming from the encoder is missed by the kit. May be a level shifter cktry can be useful(to shift logic level from 3.3V to 2.5V.). Pls help me out if any one of u has a solution to the above mentioned case.

docel
07-10-2006, 12:01 PM
Can you provide the details of the quadrature encoder?
Is the Spartan board configured proprely?

varungenius2001
07-11-2006, 02:55 PM
the rotary encoder is of metronix h40-8-1000vl. with 1000 ppr. output voltage +5V dc.

The kit is configured to lvttl level logic.

Normally it should work fine but some of the data is missed when the output of the encoder is connected to the fpga directly.

Now this means we have to convert the ttl 5v to lvttl 3v logic.......

Can a simple opamp solve this problem ? If yes then How ?

varungenius2001
07-11-2006, 03:00 PM
Hi Docel,

Thanks a lot for taking interest in my query.

Coming to the point, the rotary encoder is of metronix h40-8-1000vl. with 1000 ppr. output voltage +5V dc.

The kit is configured to lvttl level logic.

Normally it should work fine but some of the data is missed when the output of the encoder is connected to the fpga directly.

Now this means we have to convert the ttl 5v to lvttl 3v logic.......

Can a simple opamp solve this problem ? If yes then How ?


Regards.
Varun

docel
07-12-2006, 11:37 AM
Use MAX3232 as a level translator.

OR use 74LVX3245 and 74LVX4245

..OR


http://img146.imageshack.us/img146/6778/5vto3v2tu.th.jpg (http://img146.imageshack.us/my.php?image=5vto3v2tu.jpg)

varungenius2001
07-24-2006, 12:50 PM
Dear Docel,
The ICs which u mentioned are not available at my place. You have also provided a picture. Can u pls explain the working of the cktry along with the component names...............


Regards,
Varun

docel
07-25-2006, 07:48 PM
Hi Docel,

:arrow: The kit is configured to lvttl level logic.

Normally it should work fine but some of the data is missed when the output of the :arrow: encoder is connected to the fpga directly.

:arrow: Now this means we have to convert the ttl 5v to lvttl 3v logic.......

Regards.
Varun

To convert....LvTTL to TTL and vice versa. The data sheets for these devices explain everything.