Possible roles of General Purpose Output ports.

Values of this enumeration:

• GPO_OFF - Output is off (zero voltage or switched_off)
• GPO_ON - Output is on (voltage or switched_on)
• GPO_FRAME_ACTIVE - Output is on while frame exposure,read,transfer
• GPO_FRAME_ACTIVE_NEG - Output is off while frame exposure,read,transfer
• GPO_EXPOSURE_ACTIVE - Output is on while frame exposure
• GPO_EXPOSURE_ACTIVE_NEG - Output is off while frame exposure