I am working with my Roomba 615, to make it a little bit more flexible.
E.g. let it run via remote command.
To do this, I use an Arduino Nano.
In general, it works fine.
I can start the robot and make it run.
Even get sensor data.
But, I cant wake it up from sleep.
This should be the easiest part, but for me, it is not
The general specification (and all of the hundreds of forum and google posts..) say, that one has to send a digital LOW signal (500 ms) to Roomba Pin #5 (Device Detect Pin or Baud Rate Pin).
Where ddPin is my Digital Pin on the Arduino Nano Board (currently pin #1, but I tried also others).
This pin is direcly connected with Pin #5 on the Roomba Interface.
Then: GND of Arduino is connected with GND of the Roomba.
You could hook an led up to power through a resistor, and hook it up to the pin on the nano. The led should light up only when the pin goes low.
Have you tested manually that putting ground to that pin causes the roomba to wake up? Get a momentary push button switch and see if holding it down for half a second or more wakes up the roomba.