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    VOXL PM v3 (MDK-M0041-1-B-03): VBAT INA231 @ 0x44 missing (only 0x45 seen) → no `battery_status`

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    • H
      hula
      last edited by

      IMG_20250810_121243176.jpg Hardware

      • Flight controller: ModalAI Flight Core v2
      • Power module: VOXL Power Module v3, P/N MDK-M0041-1-B-03 (silk: “MODALAI APM LITE / M0041 REV?”)
      • Power applied via XT60 (battery), FC connected to PM on J13 (I²C back to FC).
        Firmware
        PX4 (ModalAI build). (I can provide the exact git tag if needed.)
        Symptom
        listener battery_status
        -> never published
        What I see
        I²C scan on the PM bus (I²C3 / bus 3): 0x45 present, 0x44 absent.
        voxlpm start -X -a 0x45 -T P5VDC
        -> voxlpm #0 on I2C bus 3 (external) address 0x45

      voxlpm status
      -> - V3 (INA231) type: P5VDC
      voltage: 5.0475 VDC
      current: 0.4464 A
      shunt: 2.5000 mV, 500.0000 mA
      rsense: 0.005600 ohm, cal: 4993
      sample: increasing

      voxlpm start -b 3 -a 0x44 -T BATT
      -> WARN [SPI_I2C] voxlpm: no instance started (no device on bus?)
      Visual inspection
      The INA231 near “BAT OUT” is marked U3 (expected VBAT monitor @ 0x44).
      Nearby strap resistors/jumpers: R12 is not populated, R13 is present. Docs indicate U3 should be strapped A1=VS, A0=GND → 0x44.
      Hypothesis
      Either U3 (INA231) is unpopulated/failed or its address strap isn’t set for 0x44 (e.g., missing 0‑Ω link at R12 if that is A1→VS).
      Since 0x45 (U4 / 5 V rail) works, the I²C path, driver (voxlpm), and power to the PM are good.
      Questions for ModalAI

      1. On MDK-M0041-1-B-03, can you confirm the intended A1/A0 strap for U3 and which designators implement those straps (e.g., R12 = A1→VS, R13 = A0→GND)?
      2. Is there any production variant of this PM where U3 is DNI or strapped to a different address than 0x44?
      3. Given the measurements above, do you recommend an RMA for this module, or is it acceptable to populate the missing strap (R12) to A1→VS to restore 0x44?
      4. Any additional checks you’d like me to run (specific test points for U3 VS, A0, A1)?
        Attachments
        Close-ups around U3, R12/R13, and the SDA/SCL/GND/5V header:

      IMG_20250810_121216316_HDR.jpg IMG_20250810_121243176.jpg

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