Initial GPS system #93
Conversation
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Critical note: This enables the charging of the RTC backup battery, on the assumption that the system is designed to set and forget the output. Further investigation into the actual needs of the RTC battery is suggested if there's any documentation available from the manufacturer. |
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GPS installs and functions as expected from previous iteration. Documentation forthcoming. Current op codes are from previous incarnation and conflict with CE op codes pending discussion of consolidation of interface commands. Actual GPS testing on this iteration is not current, as the device has terrible GPS reception, but the system has worked previously, and it is receiving well-formed NMEA sentences, and is thus expected to be fully functional. RTC battery question still pending, but it has not exploded yet. I would call this ready for wider testing and application development. |
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I would also like to point out that the LilyGO schematics are contradictory regarding the actual circuitry surrounding the battery. |
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AX2101 datasheet shows the battery charging system is set for a linear charge at 100 uA and a 2.9v cutoff. Unless otherwise informed, I will assume this is well-configured. The battery terminals are at 2.9v when tested. However, the GPS may be underpowered (~2.9v) and the ALDO3 setting not respected. Will continue to investigate, but I consider this to be a bug, not a breaking issue. |
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GPS power is correct. Removed a potential safety issue in AXP193 configuration where the 2.9v battery level was forced to 3.3v. I believe this creates a stable situation and have no reservations on anything beyond my world-class edge-case worry skills. |
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Got a clear sky: GPS testing works 100%. |
The words you wanted to hear: untested and undocumented. I need to modify rnodeconf to upload it, and documentation is . . . missing. I'll have to re-do it from the ground up.
This was based on tested code, but at least the power management is VERY VERY different from my source, so I'm not sure what happened. I'm confident, but treat is as a draft for the time being.