From 3f57320f181618b7f655077e4cb01c2b81731515 Mon Sep 17 00:00:00 2001
From: Jan Vos <jjcvos@hotmail.nl>
Date: Wed, 12 Aug 2026 11:04:35 +0200
Subject: [PATCH 1/3] implement skipping of first buffer

---
 src/dmdreader.cpp | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/dmdreader.cpp b/src/dmdreader.cpp
index 74311b3..0acf079 100644
--- a/src/dmdreader.cpp
+++ b/src/dmdreader.cpp
@@ -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;
@@ -912,12 +913,16 @@ void dmd_dma_handler() {
          loopback ? source_bytes : target_bytes);
 
   dmd_prepare_dma_sniffer();
+  switch_buffers();
+
+  if (!filled_buffer) {
+    filled_buffer = true;
+    return;
+  }
 
   frame_crc = dma_hw->sniff_data;
   dma_hw->sniff_data = 0xFFFFFFFF;  // always clean after sniffing!
 
-  switch_buffers();
-
   if (frame_crc != crc_previous_frame) {
     crc_previous_frame = frame_crc;
     frame_received = true;

From 72ae2d7eea263ac34f91ccba4b094693b41961e1 Mon Sep 17 00:00:00 2001
From: Jan Vos <jjcvos@hotmail.nl>
Date: Wed, 12 Aug 2026 16:41:55 +0200
Subject: [PATCH 2/3] adjust order of execution when buffer needs to be filled.

---
 src/dmdreader.cpp | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/src/dmdreader.cpp b/src/dmdreader.cpp
index 0acf079..9b27d9c 100644
--- a/src/dmdreader.cpp
+++ b/src/dmdreader.cpp
@@ -913,16 +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;
   }
 
-  frame_crc = dma_hw->sniff_data;
-  dma_hw->sniff_data = 0xFFFFFFFF;  // always clean after sniffing!
-
   if (frame_crc != crc_previous_frame) {
     crc_previous_frame = frame_crc;
     frame_received = true;

From bfe288aba791d76c2c440036f8464bbdc8e0cff6 Mon Sep 17 00:00:00 2001
From: Jan Vos <jjcvos@hotmail.nl>
Date: Wed, 12 Aug 2026 21:34:17 +0200
Subject: [PATCH 3/3] use the already available variable instead for
 offset_x16.

---
 src/dmdreader.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/dmdreader.cpp b/src/dmdreader.cpp
index 9b27d9c..073b227 100644
--- a/src/dmdreader.cpp
+++ b/src/dmdreader.cpp
@@ -807,7 +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) {