I dont understand where the ground from to the digital io’s come from.
I noticed that John C said that the two black wires in his picture go to the terminal block but don’t we see that they are connected to the terminal block?
Quote:
There is a pic in this post where it’s all visible except the power distribution block.
The two white wires in the zip tie go to 12v from the battery. The two black wires in the zip tie go to ground on the terminal block.
So where does the ground to digital i/o come from?
I also don’t understand why we need to use all four positive/ground pins? I got the board to power up using a 7.2V backup battery where the positive is connected to pin #1 and ground is connected to pin #3 and had it learn some buttons, so I don’t see why it is necessary to use all four pins.
We too had some issues with using the Digital IO for the IR PCB. The Digital IO lines have pull up resistors internal to the Robot controller. They will always look like a ‘1’ to your code, unless a signal can pull them down.
We chose to use the Analog inputs for the IR outputs. This way we trigger on a ‘1’ signal and are not looking for the Digital pins to go low. Choose a value somewhere between 0 and 1023 for a triggered value. The IR PCB puts out a 100ms pulse. between 0 and 5V. The grounding through IR pins 3 and 4 should be sufficient.
We strongly recommend using the 12V supplied from a fuse panel to power the IR PCB. Using 7.2V from a PWM output will drain your backup battery. The backup battery is the sole source of power for your RC communications between the Robot and the Operator interface. Unless you intend to build the on-board charging circuit, you may have spotty IR links late in in the match.