picoborgrev daisy chain connection?

Submitted by Jay on Sun, 04/13/2014 - 01:28

Forums:

Hi thanks for the previous help. The PicoBorgReverse is a great, and much simpler to use for motor control than anything I have used so far.
I was wondering if you could help me with something.
I currently have the Pi with just the PicoBorgReverse connected via the 6pins as in the instructions.
What I would like to do is add a single channel relay, that I have, to my project to turn some LED "headlights" on and off.
For the relay I need a 5v pin, a signal/trigger pin, and a ground pin.
Both 5v pins are in use on the pi for the PicoBorgReverse.
I was wondering if I could use the 5v and the ground pins that are on the PicoBorgReverse? (The ones usually used if adding another PicoBorgReverse), and the signal/trigger pin could come from one of the unused GPIO on the Pi?
Or can I just "split" one of the 5v, and one of the ground pins on the pi, off to the relay module? say using a breadboard?
I do not know if this is doable or even safe for the electronics? Sorry if this is a noob kind of question.
If not could you point me towards info for adding a relay or sensors etc, to the Pi when both 5v pins are already taken?

Thank you
Jay

piborg's picture

piborg

Sun, 04/13/2014 - 08:55

It would be fine to use one of the 5v and the ground on the PicoBorg Reverse along with a spare GPIO pin directly from the Raspberry Pis header.

The six-pin connector normally used for daisy chaining may be used for anything else which could be connected directly to the same pins on the Raspberry Pi GPIO header, not just another PicoBorg Reverse.

clankerr02

Tue, 10/18/2016 - 21:28

This is just what I was looking for. I'm in the planning process of of a ROV build. I intend to use the Picoborg reverse to power two thrusters for forward and reverse. I need to control a third thruster for the ascent and descent. I've considered using a relay to control this wired to the daisy chain connector.
I've managed to get the basic controls working and intend to use a usb controller to "Fly" the Rov. As a noob to this I've no idea how to amend the code in order to add a button on the controller to activate the required pins on the connector.

piborg's picture

piborg

Wed, 10/19/2016 - 08:38

The first thing to bear in mind is that you cannot connect a relay directly to the GPIO of the Raspberry Pi, you would probably damage the Pi if you did!

What you want is either:

  1. A relay board intended to work with logic signals
  2. Some wiring involving a transistor
  3. A board like PicoBorg which can have the relay connected directly

There is a good video explaining options 1 and 2 here:
https://www.youtube.com/watch?v=b6ZagKRnRdM

The on/off signal will need to come from a free GPIO pin on the Raspberry Pi.
There are plenty to use :)

In order to drive the relay you simply set the GPIO signal pin level to high or low.
The GPIO pin set to low will turn the relay on.
The GPIO pin set to high will turn the relay off.
There is some example code here: https://www.raspberrypi.org/forums/viewtopic.php?p=750772

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