usb<->ttl converter

Martin_1987

Hello,

I'm looking for a USB<->TTL converter for quiet some time now. The problem is that I need a converter that provides only one port for RX and TX to connect a servo motor. I could use this one https://www.sparkfun.com/products/9716 in combination with the devices on page 8 of this datasheet http://www.agaverobotics.com/products/servos/robotis/ax12/docs/AX-12.pdf. But I did not find a turnkey solution which is as small, cheap and elegant as the sparkfun converter.

Anybody who knows where I can get such a device?

Thanks for your help!

Martin

RobotWorkshop

Hello Martin,

If you only need RX and TX then you may want to checkout some of the old USB to Nokia data cables like these:

http://www.ebay.com/itm/USB-Data-Cable-For-NOKIA-6101-6102-6102i-6103-CA-42-/320919853261

http://www.ebay.com/itm/OEM-CA-53-USB-Data-Cable-for-Nokia-6133-2865-6126-2865i-/390034123646

Quite a few people were using these with the Propeller. They can do RX and TX and with some mods can also be used for programming as well. If you only need RX and TX then using these should be easy!

Robert

Duane Degn

Is there some software you're planning on using with your AX-12s?

I don't recall ever seeing a half-duplex FTDI type USB to TTL converter. The Sparkfun device, or the devices Robert linked should work with the AX-12. You just need to join the rx and tx lines. I think it would be good to add a resistor across the tx and rx lines. There may be a way of using a diode to keep the rx from "hearing" the signal from the tx though I doubt this would really be needed.

Even if you use the USB2Dynamixel converter, you'll still need to add in a power connection.

I noticed on the agaverobotics site, they used a Propeller Demo board to communicate with the AX-12 (video on right side of this page). I used the inexpensive QuickStart board to communicate with a bunch of AX-12s a few days ago.

My three wheeled omni-bot is powered by AX-12+ servos (controlled with a Propeller). There's a video of my robot performing a figure 8 in the figure 8 thread (post #177).

I don't think you'd want to use a Propeller board just as a link between the PC and servo since one of the inexpensive devices Robert linked to should work. If you wanted to control the AX-12s with a Prop, there's an object in the OBEX to make this easier.

JonnyMac

If you have one of the original USB2SER modules that Parallax made then you've go it made. Connected properly, you can even use it to program BASIC Stamp 1 modules (align Vss with >>)