Output to two devices

[Chris K]

G'Day All,

I have a Spartan2 outputting to a simple digital gauge and it's all working exactly as it should. It's a sensational piece of kit.

I also have a Blitz iColour SBC which offers basic datalogging/display and a dedicated input for AUX/WidebandO2.

When I connect both devices to the output at the same time the two of them still read but both values drop about 10-15%

So simple question; can the Spartan2 output to two devices? Is there something that I'm missing, or is it just not possible? 

TIA

[Jerald Cheong]

G'Day Chris,

This discussion might be able to shed some light on what you are seeing. I'm not sure but I'm guessing you may be seeing the same thing.

https://groups.google.com/g/14point7/c/9bIUGG54MYE

Regards.

[Chris K]

Certainly sounds like me. However I have no way of recalibrating anything, so I'm likely out of luck...

Thanks for pointing me to the discussion above!

[Jerald Cheong]

No worries, I have every intention to link it to my Hondata and an external gauge as well. So I'm doing my homework first.

Good luck with your search for a solution.

[Jeff]

I have the same question as "Jerald". I tried asking the question previously but received no answer.

I'd like to install an external AFR gauge in addition to the ECU, both feeding from the Spartan2, but not sure if that will work. The other discussion that you linked sounds like it is a bit 'hiss or miss' with a 'trial and error' approach. Is there a way of knowing before buying a gauge or other device? What parameters should one look for? I'd appreciate hearing what you've learned so far. Thanks.

[Jerald Cheong]

Hi Jeff,

I don't profess to be an expert, but as I far as my understanding goes, the current draw of the "reading" device has some level of impact to the voltage reading.

I've been exploring amplifying circuits for current but maintaining the same voltage. However, due to supply voltages, it doesn't seem to be a simple/trivial solution due to the nature of the output voltage of any Wideband O2 system, and building a circuit like that seems to be over complicating the entire set up. And it's starting to look like making compromises to me.

At the same time, I open to listening to any ideas you might have.

[Jeff]

Thanks Jerald. I was hoping there would be some basic parameters to guide the selection of compatible components, so that attempting to make some sort of "adaptor" circuit would not be necessary. Based on other posts, it sounds like some reading devices will work correctly in the setup we seek. But knowing which ones do seems to be unpredictable. Shame there isn't more input from the source for these questions. Please keep us posted if you learn more, thanks.