I’m trying to maximize limited electrical contacts (8 pin connector) between the pressure vessel with the Artemis Openlog and batteries and an external oceanographic sensor. The sensor requires five contacts for power, ground, and the three for the RS232 communication. My plan was to:
Use one open line to automatically power the main vessel electronics when the sensor is connected. (i.e the wet cable would complete the power path to the 5V regulator which powers the Artemis Openlog )
Bring out D+ and D- (reusing the common return) so I can download files via Zmodem once the system is retrieved. These arent used while it is logging, I just dont want to open the pressure vessel to grab the data. The RS232 data from the sensor is going to the Artemis RX and TX lines so unfortunately I cant put a bluetooth device there.
However, I’ve just realized I would also like two more lines for external “stop logging” and “reset” buttons, which would connect to RST and pin 32. Unfortunately, I can’t simply add more lines to the connector. If the board is not physically accessible are these needed for reliable operation. I have found sometimes the board just starts logging after power up and sometimes I need to hit the reset button.
Question: Has anyone found a creative or clever way to achieve something like these extra control signals internally—without expanding the connector? I’d appreciate any ideas or examples from similar projects where you managed to route extra signals with limited wiring.
You might be able to mount it in such a way that you can use the physical reset button from the outside? Likea small sealed extension, or flexible portion of the vessel, or something that wiggles? Or some plunger machnism that pushes the button?
As for stop logging…is this one a necessity? usually it can be helpful if you risk running out of power/storage space, but otherwise I’d skip it
The thought process was that the stop logging would help prevent the chance of the final log file from being corrupted when the device is turned off / unplugged. To free up a conductor, could I just use the power ground as the coms return. It doesn’t seem like they are isolated on the Openlog Artemis. Then I could use that for the reset line.
It would be cool to design a little driver board right inside the bulkhead that could do some basic systems monitoring for power and comms while possibly providing a bit of isolation, buffering, switching and other desirable things. For example, you could have it watch for a heartbeat from the the individual devices (and the surface?) and issue the hard resets on a timer basis. It would handle the wireless up top.