GI (general illumination)¶
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MPF includes support for GI (general illumination) light strings which are common in existing Williams and Stern machines. You can specify GI strings which you can then enable, disable, or (if the hardware supports it) dim.
GI strings in the “gis:” config section are only for older existing machines that specifically have driver-powered GI strings. New custom machines will just use LEDs for GIs, and they are configured as LEDs, not GIs.
GI Strings are actually kind of complex. Many of them are AC (even in WPC machines), and some Williams WPC machines include triacs (kind of like a transistor for AC) and “zero cross” AC waveform detection circuits so they can sync their dimming commands with the AC current wave. Later Williams WPC machines split their GI into non-dimmable (which used still used AC) and switched their dimmable to DC. Some machines also have “enable” relays that must be activated first before certain GI strings will work.
MPF hides all this complexity from you. You just define your GI strings in your machine configuration file and then you can enable, disable, and dim the dimmable ones as you wish.