Why use breakout board with Gecko 320X?

[pp7]

I am working on a 3-axis cnc. I have no plans for VFD. I have an E-stop and limit switches controlling a relay that controls 120V AC power. I am told that Gecko 320x's have optoisolation built in. What is the advantage of using a breakout board in this case? Why not wire my parallel port directly to the Gecko 320X ??

[michaelthomas]

I suppose that you could, but using a breakout board makes the process a lot easier since it has all the wire terminals that you will need already there. You could do with a very inexpensive unit like a C-10. I think they are about 30 dollars or less.

[pp7]

Thanks for the reply. I started seeing posts of problems with different breakout boards and I was wanting to keep things simple. I was thinking of using one of these and just soldering the wires to the pins. The gecko says it works with 3.3 or 5v TTL signals. I couldn't find the current draw specs of the Gecko but I'm hoping a parallel port will power it.

5x Parallel Port Connector DR25 25-Pin Adapter Female | eBay

[michaelthomas]

The boards are usually buffered as well, so the parallel port isn't really doing the powering. I had a turd board from keling.....the kl-db25. It gave me a hell of a lot of trouble. I replaced it with a PMDX-122 and all my problems disappeared. Steve Stallings at PMDX has given me an awful lot of help and understanding. That goes a long way for me.

I've never heard anything negative about the C-10's, though.

There are also boards like this which are just parallel ports with screw terminals. CNC4PC

[arizonavideo]

I am running my Gecko steppers and servo drives directly off the printer port and it has been OK.

I did have to whack the printer cable and find the right wires. I have two breakout boards but I needed to save space as both setups used a single ATX box for all the components.

It was still kind of a pain, next time I will try one of the BOB.

[RPCElectronics]

I am running my Gecko steppers and servo drives directly off the printer port and it has been OK.

I did have to whack the printer cable and find the right wires. I have two breakout boards but I needed to save space as both setups used a single ATX box for all the components.

It was still kind of a pain, next time I will try one of the BOB.

I am designing my controller around EasyDriver modules and direct connection to the parallel port. I did add some protection diodes inline with the control lines from the port.

I took a bunch of pictures during the build:

https://picasaweb.google.com/ke4nyv/...eJ9JWthqiNgQE#

[79TigerPilot]

Current I am running 203V directly from the PP. There are two issues you need to watch for. First not all PP are the same. Not only is ther the 3.3V vs 5V issue but how much current the port can sink. Add in cards generally run the IO chip pins directly to the connector with no buffering. You have to look at the opto's specification to see how much current they need to get a good data transfer to the detector. I usually desing for 16 or 20 ma so can you PP support that kind of current and at what voltage. Since there are no real published specks you just have to measure thing. I think this is why some folks have PC that work good and others do not. I discovered a second issues while playing with my setup. Had a opto sourced from 5V through a current limit resistor on the anode, the cathode went to the parallel port. I could not get the thing to work. Turns out, when the PP pin was making a zero all was fine but when it went to a high state the opto output was still showing a zero. The problem turne out to be the 5V. The mobo chip was a 3.3V chip and wasn't truly an open collector output. Current was still flowing from the 5V through the resistor and opto into the PP pin and onto the chips 3.3V rail. The current was fairly low but enough to keept the opto conducting, it never turned off.

Craig

I am working on a 3-axis cnc. I have no plans for VFD. I have an E-stop and limit switches controlling a relay that controls 120V AC power. I am told that Gecko 320x's have optoisolation built in. What is the advantage of using a breakout board in this case? Why not wire my parallel port directly to the Gecko 320X ??