markagsmith5 wrote: Fri Jun 26, 2026 6:41 pm I did capture the data from both the AFM and MAF by fitting the MAF before the AFM and running the engine, detailed in my 2nd post. I'd be very interested to know exactly how the DME uses the AFM output.
I am calculating the conversion in real time using a best fit curve, a*x^2 + b*X + c, where X is the MAF output {see MAF2AFMwSd.ino}. I guess understanding how the DME uses the AFM output would help me decide if a lookup table would be more appropriate.
My understanding of how the MAF works means that it is not so dependant on air density but the mass of air passing through it, rather than the AFM which measures volume of air and therefore needs to consider things like altitude etc. to calculate the mass of air. Of course I maybe misunderstanding how the MAF works.
The reason I chose the R4 is that it has a real DAC on A0 and not a PWM digital output.
Don't have access to my computer at the moment, so just using my phone to respond, so excuse any typos etc.
I think you have the MAF concept right. So it sounds like you are taking the MAF signal and trying to extract/replicate the flow value the AFM would generate under all the same conditions -- so that the dme gets the signal it is set up to process for those conditions. @johnb has dug into the code and developed some very detailed info on how the dme uses the load input -- see that here. @whalenlg has developed a dme emulator that can run the code against selected inputs. Both of these guys could prove to be very helpful as you continue to develop your project! I understand your R4 selection now and it makes sense. If you end up needing more brute force, Adafruit makes some impressively fast arduino-ide-compatible devices with true 12-but DAC, like the M4 Express https://www.adafruit.com/product/3857?g ... 3lEALw_wcB