- Sat Mar 20, 2021 8:41 am
#49162
The ignition signal from Speeduino is +5v, 12v or 0v. You got to adjust this in hard- (5/12v) and soft- ware (going high or low) to match your specific coil.
No "negative" signal.
This is the perfect write up for the LS1 coil, copied from MS documentation:
"The LS1 built in coil igniters (the amplifier that drives the coil's primary current based on the sequencer signal) will follow the sequencer signal pulse width. When the signal from the sequencer is high (3 to 5+ Volts - with very little current from the controller, a few dozen milliAmps), the coil current will be building. When the signal from the sequencer is pulled low (shut off), the coil will spark. The duration of the signal from the sequencer determines the dwell (though the coil igniter limits this to no more than ~8 milliseconds).
As the dwell time increases, the peak coil charge current increases. The coil output current is not as linear. The LS1 coils do not fully saturate until around 8 milliseconds, but the spark energy does not increase much when the dwell exceeds 6 milliseconds. So stick with a 'running' dwell setting near the design value of 5.6 to 5.8 milliseconds. This will keep the coils cooler and extend their life. Note that MegaSquirt-II uses a nominal dwell setting, called the 'maximum dwell', at 12.0 Volts and adjusts this for the continuously measured running voltage (since higher voltages charge the coil more quickly, the dwell is shortened, and conversely, low cranking voltages need extended dwells to properly charge the coil for easy starting).
To get 5.6 milliseconds of running dwell, the nominal dwell parameters should be set to:
Maximum Dwell 6.1 milliseconds
Maximum Spark Duration 2.0 milliseconds
Acceleration Compensation 0.6 milliseconds
Battery Voltage Compensation
Setting Net Voltage Dwell Compensation
-4.0 8.0 Volts 2.4 milliseconds
-2.0 10.0 Volts 0.9 milliseconds
0.0 12.0 Volts 0.0 milliseconds
2.0 14.0 Volts -0.5 milliseconds
4.0 16.0 Volts -0.9 milliseconds
This will give 6.1 - 0.5 = 5.6 milliseconds at 14.0 volts while running with the alternator charging normally."