In the land of the iRobot Roomba, if you want to turn it on there are presently two ways to do so.
The first way is just a simple button press of the Clean button. Or, one could use a IR remote control to also accomplish the same task. Neither choice is needed when using an EZB controller and three of its Digital ports.
In order to perform the EZB controller option a little pre-design work is required. It involves using some 26 guage wire, a soldering iron and three neat little 5 volt powered relays. The electrial wiring connection is done by soldering a pair of wires across the Clean button contacts located on the printed circuit assembly inside the Roomba that are then connected to the Normally open contacts of the 5 volt relay. Then all you do is wire the signal (White) wire from the digital port of the EZB controller to the activate port (CH1) of the relay. The relay can be turned on by a high (3.3vdc) or low (Gnd) pulse provided by the digital port of the EZB. The voltage reference (3.3vdc, or Gnd) lead is wired to the CH1 port and that will activate the relay. In the example presented in this description a high pulse that lasts for 1 second will accomplish the Clean button press to turn on the Roomba. Now, all the preceding verbiage was needed so that the Roomba is powered on and the Serial Command Interface (SCI) is able to receive serial commands from the EZB controller.
Here is a start up script that will turn on your 500, 600, 700, or 800 model Roomba.
set(d1,off) # start in the off condition
set(d1,on) # This will operate the relay and turn on Roomba
sleep(1000) # replicate a 1 second Clean button press
set(d1,off) # release relay
Now the Roomba is ready to receive serial commands.
Additional electrical connections were also made to the Spot button as well as the Dock button. With the proper sequence of button presses the Roomba can be placed into the Built in Test program and all of its sensors can be accessed and tested for proper operation.
DJ added the UART Serial terminal to the EZ Builder GUI that can be used to actually monitor the individual diagnostic test results on all the internal Roomba sensors.