ModalAI Forum

@Vinny Glad I could help, and thank you for confirming so quickly on your side.

@Vinny I hate to say this, but I believe you have a batch of defective USB cables. I was running into the same issue as @VictorG and @Michael-Mortensen , so I broke out the multimeter and confirmed that 5V and GND are swapped (note the negative 5V instead of +5V). I grabbed another generic USB cable that I had on-hand and the FCv2 powered up and connected to QGC fine.

ModalAI Support was kind enough to send me 3x replacement USBs...but unfortunately they are all mis-wired as well.

@Ansel-Misfeldt I, too, needed to enable UAVCAN so that I could connect a Here 3 GPS to the FCv2. I was able to modify the board's "default" file to re-enable UAVCAN. Happy to step you through it, just send me a DM.

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: