Output servo pulse to serial?

[Xnaron]

Does anyone know of a device or how to build a device that would take the servo output from a receiver and convert it to a serial signal.

Basically I am looking for a device that you could plug into 4 or more channels on a stock rc receiver. The device would output the servo positions to a serial port on a computer or other device. The stream of data would be something similar to what is used in the www.seetron.com mini ssc II servo controller. Basically a format like [Sync Byte][Servo Byte][Servo Position Byte]. The mini scc II drives servos from a serial signal. I would like to drive a serial signal from servo ouput. I guess its kind of the opposite as his device.

Thanks,
Brendin

[mmormota]

The FMS PIC simulator cable is a good starting point. It converts the PPM signal to bytes using a Microchip PIC microcontroller.

There are some free designs on the net.

[Malc C]

The problem I think you'll find with normal servos is that they don't feedback their position from power up, but respond to a signal being sent to them. This signal is generally a 1ms - 2ms pulse repeated every 20ms.

The SCCII sends a generated signal to each servo, the position of which is set via the [servo byte] which is a value between 0 and 254 (0 and 254 being full left and full right respectivley)

As mmormota suggests, taking the PPm signal from a buddy box would be a better way than taking it from a receiver, and there are lots of ccts on the net that describe the functioning and building of an interface based around a PIC micro. I'm sure Bruce Abbot or Eric Brouwer will jump in here and advise on how to read the signals into a windows application

[Xnaron]

The FMS PIC simulator cable is a good starting point. It converts the PPM signal to bytes using a Microchip PIC microcontroller.

There are some free designs on the net.

Thats a great idea...thanks

[Xnaron]

The problem I think you'll find with normal servos is that they don't feedback their position from power up, but respond to a signal being sent to them. This signal is generally a 1ms - 2ms pulse repeated every 20ms.

The SCCII sends a generated signal to each servo, the position of which is set via the [servo byte] which is a value between 0 and 254 (0 and 254 being full left and full right respectivley)

As mmormota suggests, taking the PPm signal from a buddy box would be a better way than taking it from a receiver, and there are lots of ccts on the net that describe the functioning and building of an interface based around a PIC micro. I'm sure Bruce Abbot or Eric Brouwer will jump in here and advise on how to read the signals into a windows application

Thanks...I think I might be going a different route as I have another idea that would work better to accomplish what I want.

[Malc C]

Does anyone know of a device or how to build a device that would take the servo output from a receiver and convert it to a serial signal.

Thanks,
Brendin

Quite by accident I came accross this site

http://www.mcmanis.com/chuck/Robotics/projects/ServoGizmo/servo-proc.html

I think it does more or less what you want. Not sure if the HEX is available.. but dropping an e-mail to the guy might bring you the results you need :)

[Xnaron]

Quite by accident I came accross this site

http://www.mcmanis.com/chuck/Robotics/projects/ServoGizmo/servo-proc.html

I think it does more or less what you want. Not sure if the HEX is available.. but dropping an e-mail to the guy might bring you the results you need :)

Thanks...that looks like it would work well.

Brendin

[AeroJDK]

I too am interested in using one of my aircraft transmitters to control a device over a serial line. Is there nothing that can be purchased off of the shelf to do this? What does the output of a Buddy Box look like if it is being connected directly to a serial line? Are there 10 bit numbers coming out of the box representing the servo's positions?

AeroJDK

[slipstick]

See post #2 above ;).

The output from a buddy box is nothing like a standard serial signal. It uses analogue coding, pulses of varying width roughly from 1-2ms encode the positions. It's not a digitally encoded signal of with any number of bits.

BTW a serial port is only 8 bit not 10 but that's enough precision for most purposes.

Steve

[Malc C]

What does the output of a Buddy Box look like if it is being connected directly to a serial line? Are there 10 bit numbers coming out of the box representing the servo's positions?

AeroJDK

A TX set to PPm mode sends signals just as Steve explained, and they look like the attached image.

[AeroJDK]

Well it sounds like the FMS PIC Simulator cable will be the way to go, I was just hoping to find something for sale that I didn't have build myself. Thanks for the help on the matter...

AeroJDK

[Malc C]

Well it sounds like the FMS PIC Simulator cable will be the way to go, I was just hoping to find something for sale that I didn't have build myself. Thanks for the help on the matter...

AeroJDK


Edit - re-read the post.. and notices its not a TX interface thats require so my comments were deleted.