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

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

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  • H Offline
    H Offline
    hula
    wrote on last edited by
    #1

    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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