the serial cable required for connecting the external device to the projector’s gpio connector, whether it’s a standard serial cable or a custom one, must be compatible with the external device.
configuring the gpio
the gpio connector can be configured to automate any number of events using the serial command code gio. each pin is defined as either an input or output depending on the desired outcome. in general, configure the pin as an input if you want the projector to respond to something the device does and as an output if you want the external device to respond to an action taken by the projector. for example, configure the pin as an output if you want the lighting in a room to automatically dim when the projector is turned on.
by using the gio command, you can also set the state of each pin as high or low. by default, the state of each pin is high. the voltage applied to pins in the high state is + 3.3v.
example 1. turn room lighting on when the projector is turned off. (assumes a control/automation unit is configured to turn the lights on when pin 2 of its input goes high.)
(gio c2 o) set pin #2 configuration to output
(gio 2 h) set pin #2 to high (state)
query command
(gio?) request the state and configuration of all pins
(gio! “hhllhlh” “ooioooi”) reply of pin state and configuration
(gio? c2) request configuration for pin #2
(gio! c2 o) reply with pin #2 configuration as output
(gio? 2) request the state of pin #2
(gio! h) reply with pin #2 state as high
real time event use the serial command rte to specify an action that is initiated at a particular time or based on an external stimulus.
for general purpose io “g”
example 2. projector powers up when a switch on the external device is turned on.
(gio c2 i) set pin #2 configuration as input
(rte g 2 h “(pwr 1)”) power on when pin #2 set to high
(rte g 2 l “(pwr 0)”) power off when pin #2 set to low