TwinTurbo.NET: Nissan 300ZX forum - No, stock ECU needs a 1° signal
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Subject No, stock ECU needs a 1° signal
     
Posted by zromtech on April 30, 2016 at 3:23 PM
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In Reply To Can you use AEM disk with stock ECU? (n/m) posted by ZXoltan on April 29, 2016 at 10:49 AM
     
Message which it filters in software to calculate RPM. The 1° signal is also used to determine if the engine is running or has started cranking (to provide faster engine starts).

The stock ECU has a co-processor (Hitachi HD6314 Universal Pulse Processor) to handle the pulsed I/Os such as the CAS signal input. The co-processor counts the interval between CAS pulses and the main processor uses that number to calculate the actual RPM with a resolution of +/- 12.5RPM. Since the ECU clock runs at 4mhz, the co-processor has no problem counting the interval between 1° CAS pulses even at 7000rpm.

Here's the specific command used by the co-processor:

 photo cas_zpsjsgkk9a9.png


- Sam

     
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