DME/KLR data logging

Talk and Tech about turbocharged 924/944/968 cars
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johnb
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Wow, that's fantastic. @whalenlg is doing something similar for the DME.

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whalenlg
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Would be cool to integrate them if feasible.

@andyb - do you have a klr schematic?

I could probably create one based on the pics on the website, but always easier to reuse what’s out there.
1986 951 - Silicon Valley

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andyb
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Hi @whalenlg
Would be cool to integrate them if feasible.
Yeah. It'd be great to have a reasonable physics sim of the engine + DME and KLR simulation ultimately. I need to focus on getting the basics of the KLR working first though. I'm currently trying to figure how to simulate the ADC. I think that will occupy me for a few days yet.
do you have a klr schematic?
Sorry, no. I've just been using the info from John's KLR pages so far, and occasionally looking at my PCB photos.

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johnb
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I have a spare KLR that I use for this stuff, so if photos would be useful let me know. I only ever did enough to understand how things work, so the drawings on my site don't have component values because I didn't really care about that. I just needed to know the basic op amp configurations, and what's logically connected to what etc.

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Tom
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I have spare KLRs is you want to borrow one...

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whalenlg
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andyb wrote: Thu Feb 05, 2026 1:55 pm Hi @whalenlg
Would be cool to integrate them if feasible.
Yeah. It'd be great to have a reasonable physics sim of the engine + DME and KLR simulation ultimately. I need to focus on getting the basics of the KLR working first though. I'm currently trying to figure how to simulate the ADC. I think that will occupy me for a few days yet.
do you have a klr schematic?
Sorry, no. I've just been using the info from John's KLR pages so far, and occasionally looking at my PCB photos.
I did a simple ADC Verilog model - 3 address bits to select which of 8 values go in, 8 data bits, 8 clock cycle latency from address change to output valid
1986 951 - Silicon Valley

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andyb
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Tom wrote: Thu Feb 05, 2026 2:37 pm I have spare KLRs is you want to borrow one...
If that was addressed to me, that is a very kind offer. But I don't really need one. I've currently got the one from my car on my desk. What I really need to do is to put it back in the car, without its metal box and probe it with a 'scope like John has done. But that would involve getting cold and damp at the moment.

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Tom
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andyb wrote: Sat Feb 07, 2026 2:16 pm
Tom wrote: Thu Feb 05, 2026 2:37 pm I have spare KLRs is you want to borrow one...
If that was addressed to me, that is a very kind offer. But I don't really need one. I've currently got the one from my car on my desk. What I really need to do is to put it back in the car, without its metal box and probe it with a 'scope like John has done. But that would involve getting cold and damp at the moment.
Well, I'm open to helping all if I can, but that was honestly directed to whalenlg since he lives down the road from me :)

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andyb
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I've implemented almost everything I can think of, but the code still doesn't seem to run correctly. I suspect the values my simulated ADC generates aren't good enough. What I've done:

Chan 0 (knock sensor noise): returns 0
Chan 1 (battery voltage): returns 200
Chan 2 (unknown): returns 0
Chan 3 (TPS supply voltage): returns 40 (I have no idea what a good number would be)
Chan 4 (MAP): returns 0 for full vacuum, 255 for 2 bar
Chan 5 (Knock sensor integrator): returns 0
Chan 6 (unknown): returns 0
Chan 7 (TPS potentiometer output): returns 0 for closed throttle and 255 for wide-open throttle

Can anyone suggest any improvements?

The code does seem to read from channel 2 and 6. I traced where channel 6 goes on my board, and it looks like it goes to ground through a 6 kOhm resistor.

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andyb
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Tom wrote: Sat Feb 07, 2026 2:25 pm Well, I'm open to helping all if I can, but that was honestly directed to whalenlg since he lives down the road from me :)
That makes sense. The risk of posting rare hardware across country borders would make me nervous.

#20

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