How to hook up non-standard step signal

[mbam]

Not sure if this is the right forum as this is not unique to a Gecko drive, however I am using a 203V for this project. Maybe should be in the general electronics section but I bet I get the best responses here.

I have an device that controls a stepper mounted on a water valve, problem is there is a proprietary drive mounted on the stepper that uses 2 inputs, a CW or CCW step signal, and it basically shuts off if not receiving step pulses, this allows the valve to move from pressure & vibration.

I want to use the 203V but need to figure out how to change the 2 existing signals to conventional step & direction.


Thanks!!

[Mariss Freimanis]

Marc,

Interesting application and you are on the right forum. Possibly two ways to solve this requirement.

1) The hard way: You need to wire some gates together to convert from CW/CCW to STP/DIR. OR the CW and CCW signals to generate STP, use the CW and CCW signals to SET and RESET a latch. The output of the latch forms the DIR signal. Build a retriggerable one-shot clocked by the STP signal. Use its output to DISABLE the G203V.

2) Maybe an easier way: The G203V uses a CPLD. It can be reprogrammed to do what you need (STP becomes CW, DIR becomes CCW, auto standby current becomes zero amps) if there is enough room left in the CPLD. I'll check Tuesday to see if there is. If there is enough room, we'll ask you to send the G203V back and we'll zap it to what you need.

Mariss

[mbam]

Mariss, I really appreciate your help.

Actually, I don't want zero on auto standby. I think that is a flaw in the existing design. The reduced standby current as exists in the present implementation of the 203V should work perfectly, maybe reduce it to 50%.

[Mariss Freimanis]

Marc,

So much the easier.

We have customer variants of our G203V CPLD code. One operates our drives in a vacuum (very bad for heat dissipation) and thus must have a zero standby current. Others have different requirements. The beauty of the G203V is that it can be customized without changing the hardware.

I took a look at what resources are left unused in the G203V's CPLD. They turn out to be considerable; about 30% of the CPLD is unused. Marcus has already coded your changes up in Verilog because he thought it would be fun to do. We will compile the code Tuesday and see if his work works.

Mariss

[mbam]

Mariss, this is more help than I could have ever hoped for. I think I would rather purchase another G203V and keep the one I have for another project I am working on. I'll call Tuesday after I get back to work.

[CoAMarcus]

mbam,

Okay, as I promised you on the phone today, I have an update. I finished coding the new firmware today, and it all looks good. As soon as I can get to our test stand, which is being taken up by G201 backorders, I will plug in a G203 with the new firmware loaded in it. It doesn't look like I will be able to do that today, but tomorrow most definitely. I will let you know how it goes tomorrow.

Marcus Freimanis

[fenn]

Originally Posted by Mariss Freimanis Others have different requirements. The beauty of the G203V is that it can be customized without changing the hardware.

sounds great, mariss. why not open-source the verilog source code so that anyone can improve the drive?

[Mariss Freimanis]

Fenn,

Sure, I'll even throw in the schematic, pcb artwork gerber files and a BOM.:-)

Mariss

[mbam]

Hi Mariss,

Any chance you have been able to test yet? My life is on hold ok - not exactly but I am excited to try your drive set up this way.

Thanks!!

[CoAMarcus]

Marc,

I am so sorry for the long delay. I had it coded and ready to go, and somehow all of the code got erased. I have been trying to salvage it from backups that ISE makes, and have found a good portion of it, but it is not tested yet. I will be doing that this week, and will change the code according to how it tests out. On paper it makes sense, but we have yet to use it in a real drive.

I apologize for taking so long on this, but the G250 and G251 distracted me from finishing this. I just checked ISE, and it appears that my code was safe but for some reason it is not implementing. I am sure it is something stupid that I am doing, but I will sort it out ASAP.

Marcus Freimanis

[CoAMarcus]

Marc,

Let me preface this message with another apology for taking so long. If there is one thing I can not stand it is wasting other people's time, and I hope it was not too much of an inconvenience.

Now that I am done apologizing, I would like to inform you of the good news: The CW/CCW G203V works perfectly on initial test. We have not run the major testing yet, but it ran correctly right off of the bat. We will finish up the testing today and let you know how it goes, but it is looking very good.

Marcus Freimanis