Interstate 75 W (RP2350) - 128x64 panel completely blank, driver chip FM6373D not initialising

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I’ve got an Interstate 75 W (RP2350 version) and two 128x64, P2.5-pitch LED panels (sold as “Sunmeit 2Pcs P2.5 Indoor Full Color LED Display Unit Board HUB75 320x160mm 128x64 Pixels SMD RGB”). The panels stay completely blank - no pixels light at all, no errors in Thonny.

Troubleshooting done so far:

  • Flashed the latest MicroPython firmware; sys.implementation confirms Interstate 75 W with RP2350, so firmware matches the board.
  • Confirmed 5V present at the panel’s own power connector with a multimeter.
  • Data connector plugs directly into the panel’s “IN” socket, correct orientation.
  • Ran a minimal script using the raw hub75 module directly (bypassing Interstate75/PicoGraphics) - runs with no errors, sets pixels, but nothing lights up.
  • Tried panel_type=Interstate75.PANEL_FM6126A, stb_invert=True, and different color_order values - no change.
  • Swapped in the second, identical panel - same result on both.

Driver chip: I read the marking off one of the ICs on the panel PCB: FM 6373D / NPT654000. From what I can find, this is a Fineng-made constant-current PWM LED driver, distinct from FM6126A.

I found a couple of forum threads describing what looks like the same failure mode with a different unsupported chip (DP3364S), where your team confirmed you’d reproduced the issue and were updating the library:

Could you let me know whether FM6373D is a known/supported chip, whether there’s an init sequence I could try, or whether this is something you’re planning to add support for? Happy to test a beta build or provide more diagnostics if useful.

Thanks,
Gene