
krempel
I just want to double check something on the PS2 cable for Roomba connection.
As I understand I need to connect to pin 3 (RXD input) and Pin 7 (ground) Your tutorials say to make sure there is no voltage or I will fry the D0 port.
So here is what I don't understand:
Pin 7 is supposed to be ground and when I connect the multimeter to pin 7 and pin 3 it shows no voltage. However, if I touch one lead of the voltmeter to the grounded base of the serial port (the outer barrel) and the other lead to pin three, I read 4.5 volts. Obviously there is voltage to pin three, but only when it is grounded to the port's barrel and not when I am connected to pin 7 as ground.
Also, pins 1 & 2 read between 12 and 14 volts when I connect the multimeter to those pins and the base of the port, yet when I connect the meter to pin 1 or 2 and the negative lead to pin seven, that voltage drops to 7.5 volts??
I suppose that I should just trust the meter that shows zero voltage when connected to pins 3 & 7, but What exactly is pin seven doing? Why does it show voltage when the multimeter is touching the grounded base and not when it is touching pin 7 ground?
Good Luck!
Me, not being patient, burned up three Roomba motherboards. I had a Factory cable from I-robot and every unit I plugged it in to burned up the communication port making it useless for robotics unless you replace the motherboard.
But, in the end, I built another cable and salvaged what I had left.
There is a wiring diagram on the hardware page though: http://www.ez-robot.com/Tutorials/Hardware.aspx?id=21
Just make sure you connect to the right pins
Mel
I dug up an 8 pin cable from an old serial modem that might work. The only problem with this one is that the ground wire connects to both pin 7 AND pin 8 in the very centre of the plug, but that one just sits in a dead rectangular hole in the roomba serial port,so it should be okay, right?
All I remember, and don't hold me responsible, it is just food for thought:
On a 7 pin connector 3 signal, 7 ground.
On a 6 pin connector 2 Signal, 6 ground.
Make sure you orient the plug correctly , or you will burn up both the Roomba AND the EZB.
The 540 Model is an EXCELLENT Heavy Duty model.
Mel