Tach Output Problems

[grippo]

What Maxzillian said is correct - the older code used the MSII injector led pin as the tach output and was on whenever the injectors were open, so it was on for several ms. The newer code outputs a 12V, .15 ms tach output. This should be sufficient, but if not it can be extended with a simple external device. I have checked that this output is indeed what the processor is outputting, but it may be hard to see on the scope if you don't know the duration of the pulse.

[RedRocketRally]

I was more wondering if Maxzillian ever got his tach working. Where the thread left off, he had identified the reversed polarity and shorter pulse and was guessing the pulse was too short for his tach to recognize, though in the earlier software versions using the injector pulse, it had worked fine. If he did get it working, I'm curious what he did so I can try that and see if it gets mine going.

Or perhaps there could be a fix through software, since the output seems quite flexible. Is it possible to make that tach output configurable? Maybe select between old or new versions, or better yet set polarity and duration?

[grippo]

I just replied to this on the beta tester thread. Yes it is possible to extend the pw in sw, or set up a duty cycle and give people control of it. But we really don't want to get into the business of handling every tach out there - there are just too many. So I intend to pick one type and use that. But I need to think about it first. There are plenty of ways to extend the tach output electronically, A 555 timer is one way. This could be put on a small perf board inside a tiny case and could provide the required signal.

[RedRocketRally]

Any rough idea for a time frame on this change? Also, is there an inexpensive brand of tachometer that is known to work with the microsquirt as it is now? I have my first race in 2 weeks, and I'd prefer to have a working tach, though I can just set up the ALED as a "shift light" for now. I have plenty of other stuff to do to the car before I mess with extra circuitry for the tach pulse (especially if a software fix is in the works).

[grippo]

I have the code finished - it puts out a 12V, 30% duty cycle on the same pin it is on now. However I have put the change in code vsn 3.230 which is a beta test code for the Sequencer but also works with all previous versions and modes. The 3.x code is the only code I will be releasing in the future because it is too difficult to maintain multiple code versions.

I can release this to you in tomrrow along with the correct ini file if you want to beta test it. Bruce tried the v3.110 code on his engine, which had been set up with 2.89 code and microsquirt just like yours I believe. He put in his msq and it fired up and ran same as the 2.89 code. The 3.110 code is very similar to to the 3.220 code - most of the differences pertain to the sequencer, except of course the tach mod, so you would be more like the second data point rather than the first. Let me know.

[RedRocketRally]

Wow! I'll be back home a week from tomorrow, and I'd be happy (more like thrilled) to beta-test it then. I am running 2.89 on microsquirt now, so I can always go back if I run into problems. Send me the files or info or whatever, and I'll fire it up as soon as I get back home.

Thanks!

[grippo]

The download file and ini file are attached.You will see some inputs you don't recognize- just leave them as default or ask me about them. You don't have to do or set anything to get the tach to work. Just load your present msq and check that everything looks reasonable, then try to start. If you have problems let me know.

[robh]

I was having the same problem (w/ 2.87x code tach output worked but w/ 2.88x code I had no tach) and in addition to that I'm running wasted spark so I was getting half the RPMs I was supposed to on my tach.

With the 3.23 code the tach reads exactly same as Megatune, Wohoo!

Thanks Al!