"going high"

[Orzyszpon]

All,

With your kind forbearance for a newbie, I ran across the following statement on
http://msextra.com/doc/ms3/firmware.html

Spark output polarity
The setting value name has been simplified. 99% of users of MS3X logic spark outputs will require "Going High" which means that the coil dwells when the output signal goes high.


What does going high mean? Is it some upper range (pardon my ignorance) or a high state (pardon my ignorance even more) of something or other?
Your kind (or even belittling reply) will be greatly appreciated, as long as it carries the requested information.

Cheers,
"Orzyszpon"

[Ollie8974]

Going high,
The voltage is at zero volts, When a tooth passes in front of the sensor, the voltage goes up to 12 volts.

Going low,
As the tooth leaves the sensor, the voltage returns to zero volts.

[dontz125]

Ollie - he's talking about spark polarity, not tooth polarity.

Orzyszpon - "Going high" means the processor pin goes from 0v to 5v to activate the coil drive circuit, charging the coil. At the end of the dwell period the goes low again, causing the coil to discharge and fire the plug. The positive control of this arrangement is safer, making it the preferred configuration.

In a "Going low" system, the processor pin is normally high to block the coil drive circuit, and by going low allows the coil to charge. When the pin returns to +5v, the charging is interrupted and the plug fires. This style has problems due to the lack of positive control, and other options for 'going low' designs are being discussed.

[Orzyszpon]

Thank you all for your clear and concise answers.