Module bitplane 

Bitplane-oriented framebuffer implementations for HUB75 LED panels.

These framebuffers store colour data as one bit-plane per colour bit (typically 8 planes for full 8-bit colour). To render, output each plane a number of times equal to its bit-weight (the MSB plane 2^7 times, the LSB plane once) — either with a DMA descriptor chain or by reprogramming the DMA address/length registers per segment from a transfer-complete interrupt — so that the weighted repetition counts produce correct BCM brightness.

All layouts store planes LSB-first (plane 0 = LSB), and each BCM segment streams a contiguous suffix of planes, repeated just enough times to bring each plane’s total coverage to its bit-weight — halving the number of DMA transfers per scan with identical brightness. Drivers should follow the FrameBuffer segment sequence rather than assuming an order; see its documentation for the segment/group/sequence terminology.

Two variants are provided:

• plain – 16-bit entries with all signals (address, latch, OE, colour) packed into each word. No external latch circuit needed.
• latched – 8-bit entries with separate address bytes, requiring an external latch circuit but halving per-entry memory.

Modules

latched

Bitplane framebuffers for an 8-bit latched HUB75 interface.

plain

Bitplane framebuffers for a 16-bit plain HUB75 interface.