The basics: I have an EEC-IV ECU from Ford and a EDIS 4 (FORD).
The SPOUT signal means: SPark OUT wich is a 50% duty-cycle at 12V. On the left edge of the squarewave, for aprox. 2 miliseconds is the DWELL time/signal. This signal is provided by EEC-IV to the TFI (the precursor of EDIS 4).
EDIS 4 needs the SAW (Spark Angle Word) signal. In theory is the same signal like SPOUT with some differences.
SAW:
- It works with 5V
- It is PWM signal
- The algebraic formula is: "The algebraic formula for calculating the SAW pulsewidth is:
SAW Pulsewidth (usec) = 1536 - (25.6 x (desired spark advance in degrees))
Range: 64 - 1792us (57.5° BTDC to 10° ATDC)
Resolution: 4us (5/32nd of a degree)
Example:
You want 29 degrees of advance.
PW = 1536 - (25.6 * 29)
PW = 1536 - (742.4)
PW = 793.6
You would send a pulse that is 793.6 microseconds long to the EDIS module.
The EDIS module will do all the work of timing the spark, you just send the advance pulse.
The EDIS has an advance range of 57.4 degrees BTDC to 10 degrees ATDC. These correspond to the SAW widths of 64 and 1792 microseconds respectively. "
In conclusion I want use the Arduino ,,to translate" the SPOUT signal into SAW signal. The problem is how to reduce the amplitude of the SPOUT signal from 12V to 5V for Arduino?
More info here: Here's a Picoscope waveform of... - Drag Radial Performance | Facebook
Thank you!