Hello Everyone! I am a mentor for a HS robotics team and they have a question for you all.
We have an ROV and we are making our own laser scaler that is controlled by a relay. How can we control the laser using BlueOS?
Our current relay: https://www.circuitbasics.com/wp-content/uploads/2015/11/SRD-05VDC-SL-C-Datasheet.pdf
Thanks in advance for helping students solve their problem.
Hi @pgraven -
I’ve got bad news for you - that relay you link isn’t going to work with the outputs available from the Navigator! You can see how to setup a relay here, but generally the Navigator can only source ~5-8 mA at 3.3v - the relay you link is mechanical and so requires significantly more current to trigger.
This solid state FET is a good option, and is also linked in that resource shared above. Generally any relay compatible with a “Raspberry Pi” from a low current/voltage perspective should work!
This good to know but the odd/ strange thing is, we got it working about 30 minutes after posting - or at least triggering the laser on/off (didn’t do any additional testing).
If it does work, will it fail over time?
With your suggestion, I’ll get them your suggested option for them to work off of next. Thanks for the quick response.
Hi @pgraven -
That’s very interesting! I would be concerned that over time, the output pin could be damaged if excessive current is being drawn. I could have just been misreading the datasheet too! It probably helps that the current draw of the lasers is very low. Glad you got things working - had you already found the documentation I linked?
Yeah, a student got it working prior to seeing your response. When I asked, I got this back in regards to how he got it working.
Used this https://www.youtube.com/watch?v=58XWVDnB7Ss to get understanding and how operation of the controls work.
Then found this Relay ON/OFF for lights control out of pixhawk to get started. Lead to updating the Ardupilot version. It gave the start to setting the relay function on the servo port on the navigator (yes the board in the video is a pixhawk but it still used the same set up).
Then found and used this https://bluerobotics.com/learn/connecting-your-device-with-navigator-and-blueos/#outputting-servo-and-relay-signals to finish setting it up for controlling them. Finally used Cockpit relay commands after the Ardupilot parameters were all set up.
I did take your suggestion and the parts were ordered from Amazon for the students to test next week.