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Skip sending of the very first buffer as it is always empty #54

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PastorL69 wants to merge 3 commits into from
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Skip sending of the very first buffer as it is always empty #54

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3f57320
implement skipping of first buffer
PastorL69 Aug 12, 2026
72ae2d7
adjust order of execution when buffer needs to be filled.
PastorL69 Aug 12, 2026
bfe288a
use the already available variable instead for offset_x16.
PastorL69 Aug 12, 2026
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10 changes: 8 additions & 2 deletions src/dmdreader.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -117,6 +117,7 @@ bool detected_1_0_0_0 = false;
bool locked_in = false;
bool plane0_shifted = false;
bool loopback = false;
bool filled_buffer = false;

// SPI PIO
PIO spi_pio;
Expand Down Expand Up @@ -806,7 +807,7 @@ void dmd_dma_handler() {
// merge the rows and convert from 4bpp to 2bpp with a LUT
uint32_t *dst, *src1, *src2;
dst = framebuf + 64; // start in the middle of 128x32 frame
src1 = framebuf + 511; // everything is stored from here onwards
src1 = framebuf + offset_x16; // everything is stored from here onwards
src2 = src1 + source_dwordsperline;

if (dmd_type == DMD_DE_X16_V1) {
Expand Down Expand Up @@ -912,12 +913,17 @@ void dmd_dma_handler() {
loopback ? source_bytes : target_bytes);

dmd_prepare_dma_sniffer();

frame_crc = dma_hw->sniff_data;
dma_hw->sniff_data = 0xFFFFFFFF; // always clean after sniffing!

switch_buffers();

// first buffer sent is empty, so allow it to fill up first.
if (!filled_buffer) {
filled_buffer = true;
return;
}

if (frame_crc != crc_previous_frame) {
crc_previous_frame = frame_crc;
frame_received = true;
Expand Down