I scoped the coil & found that 3.5ms seems to be sufficient but have been playing with different dwell to see if it makes any difference.
Wrt trigger - not sure if I understand
The ECU assumes that the coil will take Xms to charge. Then based upon the crank trigger, it "knows" the RPM hence is able to compute the different triggering timing for each of the 3 (6 in my case) wasted spark coils. The coil is connected to +12V all the time and the ECU basically ground/un-ground it based on dwell & when to fire.
So, how would rising/falling edge fall into this?