Adafruit hat on pi 4 + wavshare panel(FM6124EJ) : dark panel

1

Hi,

I’ve spent all day trying to get a wavshare 32x64 panel ( RGB Full-Colour LED Matrix Panel - 3mm Pitch, 64x32 Pixels - The Pi Hut ). I’ve been using the adafruit HAT to drive it: Adafruit RGB Matrix HAT + RTC for Raspberry Pi - Mini Kit - The Pi Hut . I belive it’s the latest version of the board(rev c)- it was bought recently. I’m using the hzeler lidbary(clones fresh from github)

I cannot for the life of me manage to get anything to display: no garbled signal, no flashes, no dim lines. I suspected it was a power issue, but I can’t manage to trigger a single led at 50% power- it’s not power draw.

I’ve bridged the E line pads.

I’ve tried recompiling the lidbrary acording to the current instructions, with snd_bcm2835 blacklisted. iomem=relaxed, and isolcpus=3 dtparam=audio=off are set.

GPIO seems to be functioning normally, and levels are getting boosted to 5v by the HAT.

I’ve tried swapping out panels and ribbon cables, but not the HAT or the pi. the PSU is the same throughout(measured 5.1v consistently).

Can’t figure out why it’s stuck high- Has anyone encountered a similar problem before? Any troubleshooting steps I might not have thought of?

2

Measuring between pin 4 and pin 15 on the HUB75 connector on the panel gives me 5v: I think this means the OE line is enabled constantly. If I disconnect power from the panel(but not the pi/hat) then I get ~70mv across it(OE being pulsed?). Presumably this is panel specific.

3

I have 128x64 FM6124EJ panel and what worked for me with adafruit triple bonnet was using regular hardware mapping, not the one dedicated for adafruit. That panel is running for me fine without any tweaking, just with setting –led_rows and led_cols, tho with pi4 you’ll prob need - - gpio_slowdown too.

4

For anyone having similar troubles: The problem was a malfunctioning level shifter on the HAT, and it’s worth checking that if nothing else is fixing it.