NCV1124 VR interface

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AndreyB
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NCV1124 VR interface

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The NCV1124 is a monolithic integrated circuit designed primarily to condition signals from sensors used to monitor rotating parts. The NCV1124 is a dual channel device. Each of the two identical channels interfaces with a variable−reluctance sensor, and continuously compares the sensor output signal to a user−programmable internal reference. An alternating input signal of appropriate amplitude at IN1 or IN2 will result in a rectangular waveform at the corresponding OUT terminal, suitable for interface to either standard microprocessors or standard logic families.
http://www.onsemi.com/PowerSolutions/product.do?id=NCV1124

soic-8 package and available for $2.34 at http://www.digikey.com/ which are both advantageous differences from MAX9926
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Re: NCV1124 VR interface

Post by kb1gtt »

The MAX9926 costs about $7 for 2 channels, as well the LM1815 costs about $7 per channel. So this chip is a couple dollars lower cost. However like the LM11815 it shares the GND with one side of the signal. The MAX9926 uses a differential input, which allows it to have a much better Common Mode Rejection (CMR). This better CMR allows for less sensitivity to electrical noise spikes and results in less noise spikes on your MCU pulse signals. So for a small number of $, you get much less electrical issues for the user.

If we are considering a different chip, I might suggest a PSoC CY8C29666 which could potentially allow 4 channels for about $6. This would be lower cost than all the existing options.
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Re: NCV1124 VR interface

Post by stefanst »

More channels would certainly be welcome by many. Consider V-Engines with variable CAM timing. Or variable CAM timing for intake and exhaust. So a V-Engine with variable CAM timing could need 5 timing inputs!

Add VSS and ABS sensors for launch control and similar shenanigans into the mix and I can see the need for at least 8 VR inputs.

I would also vote for differential input with no connection to ground. Just keeping the noise off my ground traces if at all possible is definitely preferable for a few bucks more.
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Re: NCV1124 VR interface

Post by ZHoob2004 »

Was any hardware ever built using this chip? I'm still having problems with MAX9926 on my Honda, and am looking to build an alternative.

From what I can tell I just need to bypass the MAX chip on frankenso and connect the output of whatever I build into one leg of the cam/crank jumpers.

In addition, where would I connect a third trigger channel, if I so desired?
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Re: NCV1124 VR interface

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I don't think any development has been done with this chip, or the PSoC chip.

What are your problems with the 9926? Is this that low tooth count issue? I understand many honda's have a 3rd signal. Also is your signal a VR?

I recall someone once was doing some stuff with a fairly generic op-amp. I recall some rough schematics posted some years ago. I think that might have been in the Russian side of the forums. Perhaps they have something of interest.
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Re: NCV1124 VR interface

Post by puff »

LM1815?
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Re: NCV1124 VR interface

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kb1gtt wrote:
Tue Apr 09, 2019 4:46 pm
What are your problems with the 9926? Is this that low tooth count issue? I understand many honda's have a 3rd signal. Also is your signal a VR?
The math has probably been beaten to death here, but if I'm correct I need to be above 350rpm to beat the 85ms watchdog with the 4-tooth cam wheel, and over 1400 for the single tooth.

I've tried a little to play with the 9926, but I don't think any of its modes are really suitable for what I need it to do, and the fine pitch makes it difficult to rework in place.

I believe the way I've been getting engine starts so far is being close on the 4-tooth, and random triggers being close enough that the engine is able to catch to get into the usable range of the wheel. Having a distributor probably helps here, since I can't be too far off and still get a usable spark.

What I would like to do is emulate what Honda did on this engine originally, which is use the 4-tooth wheel for cranking only and then switch to the 16/1 trigger for sequential running. I think this might be possible through the FSIO config, but I need a reliable trigger before I start messing with that.
kb1gtt wrote:
Tue Apr 09, 2019 4:46 pm
I recall someone once was doing some stuff with a fairly generic op-amp. I recall some rough schematics posted some years ago. I think that might have been in the Russian side of the forums. Perhaps they have something of interest.
I have seen a few diagrams and designs with generic comparators and such, but this looks to be an integrated solution that just requires a few passives and a lot less board space, not to mention it's cheaper than buying the individual parts.
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Re: NCV1124 VR interface

Post by kb1gtt »

What this VR? If it's either Hall or convert-able to hall, then the signal can likely bypass the 9926.
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Re: NCV1124 VR interface

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VR

I'm drafting a board with this chip that I'll be testing out once I get it back from fab.
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Re: NCV1124 VR interface

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Board draft "done".

Uses:
2x NCV1124DR2G VR chips
2x 23BR50KLFTR trim pots
1x CS-4-22YTB DPDT switch
4x 0805 22K resistors
4x 0805 22nF caps

Available here, though it may not actually work
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Re: NCV1124 VR interface

Post by kb1gtt »

Any chance of source files?
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Re: NCV1124 VR interface

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kb1gtt wrote:
Wed Apr 10, 2019 8:54 am
Any chance of source files?
So needy...

I have them on my home computer, I'll try to remember to get them up tonight.
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Re: NCV1124 VR interface

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I haven't forgotten about posting source, but my computer is across the room and I don't feel like turning it on today...
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Re: NCV1124 VR interface

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I once told my brother that I should call more often to check up and see how the world is treating him. But it's so much effort to reach into my pocket. :P So I understand more than you might think.
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Re: NCV1124 VR interface

Post by ZHoob2004 »

Still no schematics, but I got the boards and am in the process of testing them in vehicle now (it seemed to work on the bench but I'm having a little trouble).

I will say that I think my current design is a bit more than necessary. I included a switch to toggle the chips in/out of DEBUG mode, but I've since come to the conclusion that it's unnecessary in this application and should probably be removed from future variants. I'd also like to change the header layout a bit to make installation a bit easier on frankenso, but that's something for the future when I know it actually works.
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Re: NCV1124 VR interface

Post by AndreyB »

This part is in JLC library https://jlcpcb.com/parts/componentSearch?searchTxt=NCV1124 - for that alone we have to forgive a lot :(
Would software compensation for phase shift help?

I think we need a test module.

5mm screw terminal for VR inputs
2.54 header for everything else
0805 resistor(s)
power LED
output channel LEDs
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Re: NCV1124 VR interface

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Re: NCV1124 VR interface

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A board has arrived! Next step testing "one day" :(
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