I do not remember how I was giving power to the iridium modem, I wonder if I was just using the 3.3V from the arduino mega, but I may be remembering wrong. The answer should be in the Logger_and_Power.sch file (that can be opened with kicad).
Very interesting discussions about power supplies. It may be that my method of having batteries in parallel is a bit suboptimal when using these nice pololu regulators, and that it would be better to put cells in series to get to for example 8-10ish volts, and then use the pololu in step down mode - this looks like this could be more energy efficient and possible to supply more power as you pointed out. Maybe in this case the 3.3V regulator is enough, but as we have discussed it should be easy to put a 5v regulator, and to reduce quiescent current when not in use to switch it off fully with the shdn pin ( https://www.pololu.com/product/2123 ) .
Note that pololu has many regulators, including "old" designs that are much worse than the newer S7V8 series (guess they keep them to supply existing designs :) ), but these more recent S7V8FX regulators are really good :) .
Apololgies for the mess in the OMB code, I have never had the time to clean this up. Let me know if you have any questions. I think that given that the MCU and components are the same, it should be easy to adapt the OMB firmware, with just a few pin number / port number updates as we discussed :) . For the I2C / "Wire" in SF lingua ports, see for example https://github.com/sparkfun/Arduino_Apollo3/blob/v1/libraries/Wire/examples/Example2_MoreI2CPorts/Example2_MoreI2CPorts.ino and adjacent files.
This will be very exciting, looking forward to see how you develop this forward :) .
Thanks for the good discussion @gauteh @askbreivik , and very nice to meet you digitally @askbreivik :) .
The modem you use now is the same I had on:
https://github.com/jerabaul29/LoggerWavesInIce_InSituWithIridium
The PCB schematics are at:
https://github.com/jerabaul29/LoggerWavesInIce_InSituWithIridium/tree/master/PCB_electronics/Logger_and_power_v1
I do not remember how I was giving power to the iridium modem, I wonder if I was just using the 3.3V from the arduino mega, but I may be remembering wrong. The answer should be in the Logger_and_Power.sch file (that can be opened with kicad).
Very interesting discussions about power supplies. It may be that my method of having batteries in parallel is a bit suboptimal when using these nice pololu regulators, and that it would be better to put cells in series to get to for example 8-10ish volts, and then use the pololu in step down mode - this looks like this could be more energy efficient and possible to supply more power as you pointed out. Maybe in this case the 3.3V regulator is enough, but as we have discussed it should be easy to put a 5v regulator, and to reduce quiescent current when not in use to switch it off fully with the shdn pin ( https://www.pololu.com/product/2123 ) .
Note that pololu has many regulators, including "old" designs that are much worse than the newer S7V8 series (guess they keep them to supply existing designs :) ), but these more recent S7V8FX regulators are really good :) .
Apololgies for the mess in the OMB code, I have never had the time to clean this up. Let me know if you have any questions. I think that given that the MCU and components are the same, it should be easy to adapt the OMB firmware, with just a few pin number / port number updates as we discussed :) . For the I2C / "Wire" in SF lingua ports, see for example https://github.com/sparkfun/Arduino_Apollo3/blob/v1/libraries/Wire/examples/Example2_MoreI2CPorts/Example2_MoreI2CPorts.ino and adjacent files.
This will be very exciting, looking forward to see how you develop this forward :) .