This router, like a bunch that I've taken apart, has a status display driven by a series of registers. There are six 8bit registers here, and they're Fairchild 74VHC164s. The datasheet for them can be found here.
After minor poking, here's the pinout to the display PCB:
- Data (left half)
- Clock (left half)
- ???
- Clock (right half)
- Data (right half)
- VCC
- VCC
- VCC
- Ground
- Ground
Notes:
- The data ground isn't tied to chassis ground. The screws have what looks like the possibility of decoupling caps, but they're not populated, which isolates the board logic (the mainboard isn't isolated).
- It's broken in half because the display is fed by two RTL8208s, one for each half.
- Master reset is permanently disabled
- There's no latch, so have to be quick about shoving data in
All of the LEDs are active low. They're wired in a really weird way. Here's the lookup table (left to right, top to bottom):
// Row 1 0x000010, 0x000002, 0x000400, 0x000080, 0x010000, 0x002000, 0x400000, 0x080000,
// Row 2 0x000008, 0x000001, 0x000200, 0x000040, 0x008000, 0x001000, 0x200000, 0x040000,
// Row 3 0x000020, 0x000004, 0x000800, 0x000100, 0x020000, 0x004000, 0x800000, 0x100000,
You can see a quick Arduino sketch that shows how to access all the LEDs over here: