night199uk - so i got a HALMET up and running a...
so i got a HALMET up and running and monitoring my port engine RPMs. i see 67 rpms at idle right now 🙂
so now i want to configure these two values.
500ms seems like an eternity for monitoring the input pin; am I missing something?
doesn't the sample frequency traditionally have to be double the max frequency you want to sample? so i believe (according to chatgpt) the ratio for the yanmar alternator is something like 1.8?
therefore 3000 rpm = 5400 max alternator rpm, so should the sampling rate be at least 1/10800?
second, is there an accurate way to calculate the multiplier?
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I figured this out; sharing the answers to my questions for anyone else that finds this.
1) the 500ms is how often the pulse counter is sampled, not how often the pulse counter itself samples. so the pulse counter counts all the pulses (no idea what frequency), 500ms is just how often we retrieve the number of pulse from the pulse counter.
2) my 4jh5e has the pulse sensor on the flywheel apparently. i found a reference in the operations manual for configuring the B/C type displays. they use a pulse sensor value of 10.29 or 12.x for hitachi or valeo alternators. I retrieved my current value (10.29) from my C-class display. then configured my multiplier as 1/10.29 = 0.09718172983.
https://www.yanmar.no/theme/yanmarportal/uploadedFiles/Marine/productDownloads/Pleasure-operation-manual/Operation-Manual-3JH5_4JH5_4JH4_TE_4JH4_HTE_4JH4_HTE-10AJHM-M00201.pdf
this seems to give me very accurate RPM on my NMEA and I'm now able to watch the RPM of my engines.