From 28581fc2cfc4aaee6cbcb5097ea4ba98d9c1a60f Mon Sep 17 00:00:00 2001
From: Jan Vos <jjcvos@hotmail.nl>
Date: Thu, 23 Jul 2026 14:40:28 +0200
Subject: [PATCH 01/18] implement DMA sniffer method instead of a slow crc32
 lib.

---
 src/crc32.cpp     | 89 -----------------------------------------------
 src/crc32.h       |  8 -----
 src/dmdreader.cpp | 15 +++++---
 3 files changed, 10 insertions(+), 102 deletions(-)
 delete mode 100644 src/crc32.cpp
 delete mode 100644 src/crc32.h

diff --git a/src/crc32.cpp b/src/crc32.cpp
deleted file mode 100644
index 453ca5a5..00000000
--- a/src/crc32.cpp
+++ /dev/null
@@ -1,89 +0,0 @@
-/* crc32.c -- compute the CRC-32 of a data stream
- * Copyright (C) 1995-1996 Mark Adler
- * For conditions of distribution and use, see copyright notice in zlib.h
- */
-
-/* $Id: crc32.c,v 1.1 2007/10/07 20:47:35 matthias Exp $ */
-
-#include "crc32.h"
-
-/* ========================================================================
- * Table of CRC-32's of all single-byte values (made by make_crc_table)
- */
-static uint32_t crc_table[256] = {
-    0x00000000L, 0x77073096L, 0xee0e612cL, 0x990951baL, 0x076dc419L,
-    0x706af48fL, 0xe963a535L, 0x9e6495a3L, 0x0edb8832L, 0x79dcb8a4L,
-    0xe0d5e91eL, 0x97d2d988L, 0x09b64c2bL, 0x7eb17cbdL, 0xe7b82d07L,
-    0x90bf1d91L, 0x1db71064L, 0x6ab020f2L, 0xf3b97148L, 0x84be41deL,
-    0x1adad47dL, 0x6ddde4ebL, 0xf4d4b551L, 0x83d385c7L, 0x136c9856L,
-    0x646ba8c0L, 0xfd62f97aL, 0x8a65c9ecL, 0x14015c4fL, 0x63066cd9L,
-    0xfa0f3d63L, 0x8d080df5L, 0x3b6e20c8L, 0x4c69105eL, 0xd56041e4L,
-    0xa2677172L, 0x3c03e4d1L, 0x4b04d447L, 0xd20d85fdL, 0xa50ab56bL,
-    0x35b5a8faL, 0x42b2986cL, 0xdbbbc9d6L, 0xacbcf940L, 0x32d86ce3L,
-    0x45df5c75L, 0xdcd60dcfL, 0xabd13d59L, 0x26d930acL, 0x51de003aL,
-    0xc8d75180L, 0xbfd06116L, 0x21b4f4b5L, 0x56b3c423L, 0xcfba9599L,
-    0xb8bda50fL, 0x2802b89eL, 0x5f058808L, 0xc60cd9b2L, 0xb10be924L,
-    0x2f6f7c87L, 0x58684c11L, 0xc1611dabL, 0xb6662d3dL, 0x76dc4190L,
-    0x01db7106L, 0x98d220bcL, 0xefd5102aL, 0x71b18589L, 0x06b6b51fL,
-    0x9fbfe4a5L, 0xe8b8d433L, 0x7807c9a2L, 0x0f00f934L, 0x9609a88eL,
-    0xe10e9818L, 0x7f6a0dbbL, 0x086d3d2dL, 0x91646c97L, 0xe6635c01L,
-    0x6b6b51f4L, 0x1c6c6162L, 0x856530d8L, 0xf262004eL, 0x6c0695edL,
-    0x1b01a57bL, 0x8208f4c1L, 0xf50fc457L, 0x65b0d9c6L, 0x12b7e950L,
-    0x8bbeb8eaL, 0xfcb9887cL, 0x62dd1ddfL, 0x15da2d49L, 0x8cd37cf3L,
-    0xfbd44c65L, 0x4db26158L, 0x3ab551ceL, 0xa3bc0074L, 0xd4bb30e2L,
-    0x4adfa541L, 0x3dd895d7L, 0xa4d1c46dL, 0xd3d6f4fbL, 0x4369e96aL,
-    0x346ed9fcL, 0xad678846L, 0xda60b8d0L, 0x44042d73L, 0x33031de5L,
-    0xaa0a4c5fL, 0xdd0d7cc9L, 0x5005713cL, 0x270241aaL, 0xbe0b1010L,
-    0xc90c2086L, 0x5768b525L, 0x206f85b3L, 0xb966d409L, 0xce61e49fL,
-    0x5edef90eL, 0x29d9c998L, 0xb0d09822L, 0xc7d7a8b4L, 0x59b33d17L,
-    0x2eb40d81L, 0xb7bd5c3bL, 0xc0ba6cadL, 0xedb88320L, 0x9abfb3b6L,
-    0x03b6e20cL, 0x74b1d29aL, 0xead54739L, 0x9dd277afL, 0x04db2615L,
-    0x73dc1683L, 0xe3630b12L, 0x94643b84L, 0x0d6d6a3eL, 0x7a6a5aa8L,
-    0xe40ecf0bL, 0x9309ff9dL, 0x0a00ae27L, 0x7d079eb1L, 0xf00f9344L,
-    0x8708a3d2L, 0x1e01f268L, 0x6906c2feL, 0xf762575dL, 0x806567cbL,
-    0x196c3671L, 0x6e6b06e7L, 0xfed41b76L, 0x89d32be0L, 0x10da7a5aL,
-    0x67dd4accL, 0xf9b9df6fL, 0x8ebeeff9L, 0x17b7be43L, 0x60b08ed5L,
-    0xd6d6a3e8L, 0xa1d1937eL, 0x38d8c2c4L, 0x4fdff252L, 0xd1bb67f1L,
-    0xa6bc5767L, 0x3fb506ddL, 0x48b2364bL, 0xd80d2bdaL, 0xaf0a1b4cL,
-    0x36034af6L, 0x41047a60L, 0xdf60efc3L, 0xa867df55L, 0x316e8eefL,
-    0x4669be79L, 0xcb61b38cL, 0xbc66831aL, 0x256fd2a0L, 0x5268e236L,
-    0xcc0c7795L, 0xbb0b4703L, 0x220216b9L, 0x5505262fL, 0xc5ba3bbeL,
-    0xb2bd0b28L, 0x2bb45a92L, 0x5cb36a04L, 0xc2d7ffa7L, 0xb5d0cf31L,
-    0x2cd99e8bL, 0x5bdeae1dL, 0x9b64c2b0L, 0xec63f226L, 0x756aa39cL,
-    0x026d930aL, 0x9c0906a9L, 0xeb0e363fL, 0x72076785L, 0x05005713L,
-    0x95bf4a82L, 0xe2b87a14L, 0x7bb12baeL, 0x0cb61b38L, 0x92d28e9bL,
-    0xe5d5be0dL, 0x7cdcefb7L, 0x0bdbdf21L, 0x86d3d2d4L, 0xf1d4e242L,
-    0x68ddb3f8L, 0x1fda836eL, 0x81be16cdL, 0xf6b9265bL, 0x6fb077e1L,
-    0x18b74777L, 0x88085ae6L, 0xff0f6a70L, 0x66063bcaL, 0x11010b5cL,
-    0x8f659effL, 0xf862ae69L, 0x616bffd3L, 0x166ccf45L, 0xa00ae278L,
-    0xd70dd2eeL, 0x4e048354L, 0x3903b3c2L, 0xa7672661L, 0xd06016f7L,
-    0x4969474dL, 0x3e6e77dbL, 0xaed16a4aL, 0xd9d65adcL, 0x40df0b66L,
-    0x37d83bf0L, 0xa9bcae53L, 0xdebb9ec5L, 0x47b2cf7fL, 0x30b5ffe9L,
-    0xbdbdf21cL, 0xcabac28aL, 0x53b39330L, 0x24b4a3a6L, 0xbad03605L,
-    0xcdd70693L, 0x54de5729L, 0x23d967bfL, 0xb3667a2eL, 0xc4614ab8L,
-    0x5d681b02L, 0x2a6f2b94L, 0xb40bbe37L, 0xc30c8ea1L, 0x5a05df1bL,
-    0x2d02ef8dL};
-
-#define DO1(buf) crc = crc_table[((int)crc ^ (*buf++)) & 0xff] ^ (crc >> 8);
-#define DO2(buf) \
-  DO1(buf);      \
-  DO1(buf);
-#define DO4(buf) \
-  DO2(buf);      \
-  DO2(buf);
-#define DO8(buf) \
-  DO4(buf);      \
-  DO4(buf);
-
-uint32_t crc32(uint32_t crc, const uint8_t *buf, uint32_t len) {
-  if (!buf) return (0L);
-  crc = crc ^ 0xffffffffL;
-  while (len >= 8) {
-    DO8(buf);
-    len -= 8;
-  }
-  if (len) do {
-      DO1(buf);
-    } while (--len);
-  return (crc ^ 0xffffffffL);
-}
diff --git a/src/crc32.h b/src/crc32.h
deleted file mode 100644
index b9e0e359..00000000
--- a/src/crc32.h
+++ /dev/null
@@ -1,8 +0,0 @@
-#ifndef CRC32_H
-#define CRC32_H
-
-#include <stdint.h>
-
-uint32_t crc32(uint32_t crc, const uint8_t *buf, uint32_t len);
-
-#endif
\ No newline at end of file
diff --git a/src/dmdreader.cpp b/src/dmdreader.cpp
index a47cd79a..436b2dc1 100644
--- a/src/dmdreader.cpp
+++ b/src/dmdreader.cpp
@@ -4,7 +4,6 @@
 #include <cstdint>
 #include <cstdlib>
 
-#include "crc32.h"
 #include "dmd_counter.h"
 #include "dmd_interface.h"
 #include "dmdreader_pins.h"
@@ -629,6 +628,10 @@ void dmd_dma_reset() {
  *
  */
 void dmd_dma_handler() {
+  // get the frame crc by sniffing the DMA transfer at no cpu cost
+  frame_crc = dma_hw->sniff_data;
+  dma_hw->sniff_data = 0xFFFFFFFF; // always clean after sniffing.
+
   dmd_set_and_enable_new_dma_target();
 
   if (dmd_type == DMD_DE_X16_V2) {
@@ -890,9 +893,6 @@ void dmd_dma_handler() {
   memcpy(current_framebuf, processingbuf,
          loopback ? source_bytes : target_bytes);
 
-  frame_crc =
-      crc32(0, current_framebuf, loopback ? source_bytes : target_bytes);
-
   switch_buffers();
 
   if (frame_crc != crc_previous_frame) {
@@ -1485,6 +1485,11 @@ bool dmdreader_init(bool return_on_no_detection) {
   channel_config_set_dreq(&dmd_dma_channel_cfg,
                           pio_get_dreq(dmd_pio, dmd_sm, false));
 
+  // Configure CRC32 DMA sniffer to detect duplicate frames
+  channel_config_set_sniff_enable(&dmd_dma_channel_cfg, true);
+  dma_sniffer_enable(dmd_dma_channel, DMA_SNIFF_CTRL_CALC_VALUE_CRC32, true);
+  dma_sniffer_set_data_accumulator(0xFFFFFFFF);
+
   // Configure the DMA channel. As soon as the PIO pushed a specified number
   // of words to its RX FIFO, the DMA transfer will be triggered. The amount
   // of words to transfer is source_dwordsperframe.
@@ -1606,4 +1611,4 @@ uint8_t *dmdreader_loopback_render() {
 }
 
 uint16_t dmdreader_get_source_width() { return source_width; }
-uint16_t dmdreader_get_source_height() { return source_height; }
+uint16_t dmdreader_get_source_height() { return source_height; }
\ No newline at end of file

From f82abd5c4a96570301b3722d7cb01fcb652a21e6 Mon Sep 17 00:00:00 2001
From: Jan Vos <jjcvos@hotmail.nl>
Date: Thu, 23 Jul 2026 18:00:23 +0200
Subject: [PATCH 02/18] try with a crc history implemented

---
 src/dmdreader.cpp | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/src/dmdreader.cpp b/src/dmdreader.cpp
index 436b2dc1..364a95b4 100644
--- a/src/dmdreader.cpp
+++ b/src/dmdreader.cpp
@@ -84,6 +84,7 @@ uint16_t source_lineoversampling;
 uint16_t source_dwordsperline;
 uint16_t source_mergeplanes;
 uint16_t offset[MAX_PLANESPERFRAME];
+uint32_t crc_history[MAX_PLANESPERFRAME];
 
 static uint8_t *alloc_aligned_buffer(size_t size, size_t alignment,
                                      void **base_out) {
@@ -561,6 +562,15 @@ upscale_4bit_0_4_to_0_15(uint32_t input) {
 // upscale_4bit_0_4_to_0_15() END
 // -------------------------------
 
+// Keep track of the CRCs for planehistory systems
+void update_crc_history() {
+  crc_previous_frame = crc_history[0];
+  for (int i = 0; i < source_planehistoryperframe; i++) {
+    crc_history[i] = crc_history[i + 1];
+  }
+  crc_history[source_planehistoryperframe] = frame_crc;
+}
+
 void switch_buffers() {
   uint8_t *previousPlaneBuffer = currentPlaneBuffer;
   // Switch to next plane and frame buffers
@@ -579,6 +589,7 @@ void switch_buffers() {
                                 source_planehistoryperframe)],
            previousPlaneBuffer,
            source_bytesperplane * source_planehistoryperframe);
+    update_crc_history();
   }
 }
 
@@ -1468,6 +1479,7 @@ bool dmdreader_init(bool return_on_no_detection) {
   // Calculate offsets for the first pixel of each plane and cache these.
   for (int i = 0; i < MAX_PLANESPERFRAME; i++) {
     offset[i] = i * source_dwordsperplane;
+    crc_history[i] = 0; // initialize to 0
   }
 
   // Read a 128x16 frame but process as 128x32, so, change the number of

From dd13dbfaa6a0be4843ed37a2ca09ad5c67972b12 Mon Sep 17 00:00:00 2001
From: Jan Vos <jjcvos@hotmail.nl>
Date: Thu, 23 Jul 2026 18:27:50 +0200
Subject: [PATCH 03/18] debug print

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

diff --git a/src/dmdreader.cpp b/src/dmdreader.cpp
index 364a95b4..04ff34e5 100644
--- a/src/dmdreader.cpp
+++ b/src/dmdreader.cpp
@@ -907,6 +907,7 @@ void dmd_dma_handler() {
   switch_buffers();
 
   if (frame_crc != crc_previous_frame) {
+    Serial.printf("got frame: %d\n", frame_crc);
     crc_previous_frame = frame_crc;
     frame_received = true;
   }

From bb87feed671174d25bc7db2522ff8d57f6c52b23 Mon Sep 17 00:00:00 2001
From: Jan Vos <jjcvos@hotmail.nl>
Date: Fri, 24 Jul 2026 11:20:29 +0200
Subject: [PATCH 04/18] advanced crc array comparing

---
 src/dmdreader.cpp | 59 +++++++++++++++++++++++++++++++++--------------
 1 file changed, 42 insertions(+), 17 deletions(-)

diff --git a/src/dmdreader.cpp b/src/dmdreader.cpp
index 04ff34e5..184ada2b 100644
--- a/src/dmdreader.cpp
+++ b/src/dmdreader.cpp
@@ -84,7 +84,6 @@ uint16_t source_lineoversampling;
 uint16_t source_dwordsperline;
 uint16_t source_mergeplanes;
 uint16_t offset[MAX_PLANESPERFRAME];
-uint32_t crc_history[MAX_PLANESPERFRAME];
 
 static uint8_t *alloc_aligned_buffer(size_t size, size_t alignment,
                                      void **base_out) {
@@ -119,8 +118,15 @@ uint8_t *framebuf3;
 uint8_t *current_framebuf;
 uint8_t *framebuf_to_send;
 
+// crc array used to prevent duplicate frames
+uint8_t *prev_crc;
+uint8_t *current_crc;
+
+size_t crc_bytes;
+
 uint32_t frame_crc = 0;
 uint32_t crc_previous_frame = 0;
+
 bool detected_0_1_0_1 = false;
 bool detected_1_0_0_0 = false;
 bool locked_in = false;
@@ -562,15 +568,6 @@ upscale_4bit_0_4_to_0_15(uint32_t input) {
 // upscale_4bit_0_4_to_0_15() END
 // -------------------------------
 
-// Keep track of the CRCs for planehistory systems
-void update_crc_history() {
-  crc_previous_frame = crc_history[0];
-  for (int i = 0; i < source_planehistoryperframe; i++) {
-    crc_history[i] = crc_history[i + 1];
-  }
-  crc_history[source_planehistoryperframe] = frame_crc;
-}
-
 void switch_buffers() {
   uint8_t *previousPlaneBuffer = currentPlaneBuffer;
   // Switch to next plane and frame buffers
@@ -589,7 +586,6 @@ void switch_buffers() {
                                 source_planehistoryperframe)],
            previousPlaneBuffer,
            source_bytesperplane * source_planehistoryperframe);
-    update_crc_history();
   }
 }
 
@@ -906,11 +902,20 @@ void dmd_dma_handler() {
 
   switch_buffers();
 
-  if (frame_crc != crc_previous_frame) {
-    Serial.printf("got frame: %d\n", frame_crc);
-    crc_previous_frame = frame_crc;
+  if (crc_bytes >= sizeof(uint32_t)) {
+    memmove(&current_crc[0], &current_crc[sizeof(uint32_t)],
+            crc_bytes - sizeof(uint32_t));
+    memcpy(&current_crc[crc_bytes - sizeof(uint32_t)], &frame_crc,
+           sizeof(uint32_t));
+  } else {
+    memcpy(current_crc, &frame_crc, sizeof(uint32_t));
+  }
+
+  if (!std::is_permutation(current_crc, current_crc + crc_bytes, prev_crc)) {
     frame_received = true;
+    Serial.printf("got legitimate frame: %X08\n", frame_crc);
   }
+  memcpy(prev_crc, current_crc, crc_bytes);
 }
 
 void dmdreader_error_blink(bool no_error) {
@@ -1448,11 +1453,29 @@ bool dmdreader_init(bool return_on_no_detection) {
 
     size_t processing_bytes = source_bytes * source_lineoversampling;
 
+    // The CRC history needs to be configured here.
+    // 1 for non plane systems, 2 for Gottlieb, and 3 for WPC/similar systems.
+    // Any new systems that make use of a potential different plane/history 
+    // setup -> check code below to see if it grants a desired result.
+    uint8_t crc_history_count = 1;
+    if (source_planehistoryperframe > 0) {
+      if (source_planesperframe - source_planehistoryperframe == 1) {
+        // WPC and any system using a similar history plane setup
+        crc_history_count = source_planesperframe;
+      } else if (source_planesperframe % source_planehistoryperframe == 0) {
+        // Gottlieb: plane history is half the amount of total planes.
+        crc_history_count = source_planesperframe / source_planehistoryperframe;
+      }
+    }
+    crc_bytes = crc_history_count * sizeof(uint32_t);
+
     planebuf1 = alloc_aligned_buffer(plane_bytes, 4, nullptr);
     planebuf2 = alloc_aligned_buffer(plane_bytes, 4, nullptr);
     processingbuf = alloc_aligned_buffer(processing_bytes, 8, nullptr);
     framebuf1 = alloc_aligned_buffer(source_bytes, 8, nullptr);
     framebuf2 = alloc_aligned_buffer(source_bytes, 8, nullptr);
+    current_crc = alloc_aligned_buffer(crc_bytes, 4, nullptr);
+    prev_crc = alloc_aligned_buffer(crc_bytes, 4, nullptr);
     size_t framebuf3_bytes = target_bytes;
     size_t loopback_render_bytes =
         source_width * source_height * 4 / 8;  // 4bpp render buffer
@@ -1462,7 +1485,8 @@ bool dmdreader_init(bool return_on_no_detection) {
     framebuf3 = alloc_aligned_buffer(framebuf3_bytes, 8, nullptr);
 
     dmdreader_error_blink(planebuf1 && planebuf2 && processingbuf &&
-                          framebuf1 && framebuf2 && framebuf3);
+                          framebuf1 && framebuf2 && framebuf3 &&
+                          current_crc && prev_crc);
 
     memset(planebuf1, 0, plane_bytes);
     memset(planebuf2, 0, plane_bytes);
@@ -1470,6 +1494,8 @@ bool dmdreader_init(bool return_on_no_detection) {
     memset(framebuf1, 0, source_bytes);
     memset(framebuf2, 0, source_bytes);
     memset(framebuf3, 0, framebuf3_bytes);
+    memset(current_crc, 0, crc_bytes);
+    memset(prev_crc, 0, crc_bytes);
   }
 
   currentPlaneBuffer = planebuf2;
@@ -1480,7 +1506,6 @@ bool dmdreader_init(bool return_on_no_detection) {
   // Calculate offsets for the first pixel of each plane and cache these.
   for (int i = 0; i < MAX_PLANESPERFRAME; i++) {
     offset[i] = i * source_dwordsperplane;
-    crc_history[i] = 0; // initialize to 0
   }
 
   // Read a 128x16 frame but process as 128x32, so, change the number of
@@ -1565,7 +1590,7 @@ void dmdreader_spi_init() {
 bool dmdreader_spi_send() {
   if (!loopback && frame_received) {
     frame_received = false;
-    spi_send_pix(framebuf_to_send, frame_crc, true);
+    spi_send_pix(framebuf_to_send, 0, true);
 
     return true;
   }

From 2ec2a6ae7e0773f07699d5e89eef0734a729a915 Mon Sep 17 00:00:00 2001
From: Jan Vos <jjcvos@hotmail.nl>
Date: Fri, 24 Jul 2026 22:17:59 +0200
Subject: [PATCH 05/18] Implement a buffer filled check to prevent sending the
 first frame as blank, actually send correct stream only.

---
 src/dmdreader.cpp | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/dmdreader.cpp b/src/dmdreader.cpp
index 184ada2b..4812004b 100644
--- a/src/dmdreader.cpp
+++ b/src/dmdreader.cpp
@@ -132,6 +132,7 @@ bool detected_1_0_0_0 = false;
 bool locked_in = false;
 bool plane0_shifted = false;
 bool loopback = false;
+bool filled_buffer;
 
 // SPI PIO
 PIO spi_pio;
@@ -912,8 +913,11 @@ void dmd_dma_handler() {
   }
 
   if (!std::is_permutation(current_crc, current_crc + crc_bytes, prev_crc)) {
+    if (!filled_buffer) {
+      filled_buffer = true;
+      return;
+    }
     frame_received = true;
-    Serial.printf("got legitimate frame: %X08\n", frame_crc);
   }
   memcpy(prev_crc, current_crc, crc_bytes);
 }

From dc342d9e2226bbb5e5ca030d32541d2f6e636326 Mon Sep 17 00:00:00 2001
From: Jan Vos <jjcvos@hotmail.nl>
Date: Fri, 24 Jul 2026 22:35:34 +0200
Subject: [PATCH 06/18] call it a little earlier

---
 src/dmdreader.cpp | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/dmdreader.cpp b/src/dmdreader.cpp
index 4812004b..c83b97cc 100644
--- a/src/dmdreader.cpp
+++ b/src/dmdreader.cpp
@@ -902,6 +902,10 @@ void dmd_dma_handler() {
          loopback ? source_bytes : target_bytes);
 
   switch_buffers();
+  if (!filled_buffer) {
+    filled_buffer = true;
+    return;
+  }
 
   if (crc_bytes >= sizeof(uint32_t)) {
     memmove(&current_crc[0], &current_crc[sizeof(uint32_t)],
@@ -913,10 +917,6 @@ void dmd_dma_handler() {
   }
 
   if (!std::is_permutation(current_crc, current_crc + crc_bytes, prev_crc)) {
-    if (!filled_buffer) {
-      filled_buffer = true;
-      return;
-    }
     frame_received = true;
   }
   memcpy(prev_crc, current_crc, crc_bytes);

From ebfb0711b2fd58b058a5ba1c982de13daa3591f1 Mon Sep 17 00:00:00 2001
From: Jan Vos <jjcvos@hotmail.nl>
Date: Fri, 24 Jul 2026 23:37:26 +0200
Subject: [PATCH 07/18] remove unused function, cleanup spi header

---
 src/dmdreader.cpp | 41 ++++++++---------------------------------
 1 file changed, 8 insertions(+), 33 deletions(-)

diff --git a/src/dmdreader.cpp b/src/dmdreader.cpp
index c83b97cc..b819ac2e 100644
--- a/src/dmdreader.cpp
+++ b/src/dmdreader.cpp
@@ -21,8 +21,7 @@ typedef struct buf32_t {
 
 // SPI data types and header blocks
 // header block length should always be a multiple of 32bit
-#define SPI_BLOCK_PIX 0xcc33      // DMD frame
-#define SPI_BLOCK_PIX_CRC 0x44ee  // DMD frame with CRC32 checksum
+#define SPI_BLOCK_PIX 0x44ee  // DMD frame
 
 typedef struct __attribute__((__packed__)) block_header_t {
   uint16_t block_type;  // block type
@@ -34,16 +33,9 @@ typedef struct __attribute__((__packed__)) block_pix_header_t {
   uint16_t rows;          // number of rows
   uint16_t bitsperpixel;  // bits per pixel
   uint16_t padding;
+  uint32_t reserved;
 } block_pix_header_t __attribute__((aligned(4)));
 
-typedef struct __attribute__((__packed__)) block_pix_crc_header_t {
-  uint16_t columns;       // number of columns
-  uint16_t rows;          // number of rows
-  uint16_t bitsperpixel;  // bits per pixel
-  uint16_t padding;
-  uint32_t crc32;  // crc32 of the pixel data
-} block_pix_crc_header_t __attribute__((aligned(4)));
-
 DmdType dmd_type;
 
 // Line oversampling
@@ -132,7 +124,7 @@ bool detected_1_0_0_0 = false;
 bool locked_in = false;
 bool plane0_shifted = false;
 bool loopback = false;
-bool filled_buffer;
+bool filled_buffer = false;
 
 // SPI PIO
 PIO spi_pio;
@@ -214,23 +206,6 @@ bool spi_busy() {
   return false;
 }
 
-/**
- * @brief Abort running SPI transfers. This can be necessary in case the SPI
- * master hangs
- *
- */
-void spi_abort() {
-  if (dma_channel_is_busy(spi_dma_channel)) {
-    dma_channel_abort(spi_dma_channel);
-  }
-
-  if (!(pio_sm_is_tx_fifo_empty(spi_pio, spi_sm))) {
-    pio_sm_clear_fifos(spi_pio, spi_sm);
-  }
-
-  spi_dma_running = false;
-}
-
 /**
  * @brief Notify on pin SPI0_CS that data are ready on SPI
  *
@@ -252,16 +227,15 @@ void finish_spi() { digitalWrite(SPI0_CS, LOW); }
  *
  * @param pixbuf a frame to send
  */
-bool spi_send_pix(uint8_t *pixbuf, uint32_t crc32, bool skip_when_busy) {
-  block_header_t h = {.block_type = SPI_BLOCK_PIX_CRC};
-  block_pix_crc_header_t ph = {};
+bool spi_send_pix(uint8_t *pixbuf, bool skip_when_busy) {
+  block_header_t h = {.block_type = SPI_BLOCK_PIX};
+  block_pix_header_t ph = {};
 
   // round length to 4-byte blocks
   h.len = (((target_bytes + 3) / 4) * 4) + sizeof(h) + sizeof(ph);
   ph.columns = source_width;
   ph.rows = source_height;
   ph.bitsperpixel = target_bitsperpixel;
-  ph.crc32 = crc32;
 
   if (skip_when_busy) {
     if (spi_busy()) return false;
@@ -919,6 +893,7 @@ void dmd_dma_handler() {
   if (!std::is_permutation(current_crc, current_crc + crc_bytes, prev_crc)) {
     frame_received = true;
   }
+  
   memcpy(prev_crc, current_crc, crc_bytes);
 }
 
@@ -1594,7 +1569,7 @@ void dmdreader_spi_init() {
 bool dmdreader_spi_send() {
   if (!loopback && frame_received) {
     frame_received = false;
-    spi_send_pix(framebuf_to_send, 0, true);
+    spi_send_pix(framebuf_to_send, true);
 
     return true;
   }

From 51d416fd7d01edd4cd9a874654fdfff552a1b4c1 Mon Sep 17 00:00:00 2001
From: Jan Vos <jjcvos@hotmail.nl>
Date: Fri, 24 Jul 2026 23:43:41 +0200
Subject: [PATCH 08/18] more clean up and formatting

---
 src/dmdreader.cpp | 111 +++++++++++++++++++---------------------------
 1 file changed, 46 insertions(+), 65 deletions(-)

diff --git a/src/dmdreader.cpp b/src/dmdreader.cpp
index b819ac2e..292f304c 100644
--- a/src/dmdreader.cpp
+++ b/src/dmdreader.cpp
@@ -301,11 +301,10 @@ uint64_t read_clock_count() {
 }
 
 DmdType detect_dmd() {
-
   uint64_t signals = read_clock_count();
   uint32_t dotclk = signals >> 32;
-  uint16_t rclk = signals >> 16; // never exceeds 25000
-  uint16_t rdata = signals; // never exceeds 600
+  uint16_t rclk = signals >> 16;  // never exceeds 25000
+  uint16_t rdata = signals;       // never exceeds 600
 
   // By checking DOTCLK, RCLK and RDATA we can identify system types
   // All values are based on a 1000ms sample of data
@@ -612,7 +611,7 @@ void dmd_dma_reset() {
 void dmd_dma_handler() {
   // get the frame crc by sniffing the DMA transfer at no cpu cost
   frame_crc = dma_hw->sniff_data;
-  dma_hw->sniff_data = 0xFFFFFFFF; // always clean after sniffing.
+  dma_hw->sniff_data = 0xFFFFFFFF;  // always clean after sniffing.
 
   dmd_set_and_enable_new_dma_target();
 
@@ -645,7 +644,8 @@ void dmd_dma_handler() {
   // used. So only the new plane data is fixed here.
   for (int i = 0; i < source_dwordsperframe; i++) {
     v = (buf32_t *)planebuf;
-    *planebuf = (v->byte3 << 24) | (v->byte2 << 16) | (v->byte1 << 8) | (v->byte0);
+    *planebuf =
+        (v->byte3 << 24) | (v->byte2 << 16) | (v->byte1 << 8) | (v->byte0);
     planebuf++;
   }
 
@@ -769,8 +769,8 @@ void dmd_dma_handler() {
   if (dmd_type == DMD_DE_X16_V1 || dmd_type == DMD_DE_X16_V2) {
     // 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
+    dst = framebuf + 64;    // start in the middle of 128x32 frame
+    src1 = framebuf + offset_x16;  // everything is stored from here onwards
     src2 = src1 + source_dwordsperline;
 
     if (dmd_type == DMD_DE_X16_V1) {
@@ -893,7 +893,7 @@ void dmd_dma_handler() {
   if (!std::is_permutation(current_crc, current_crc + crc_bytes, prev_crc)) {
     frame_received = true;
   }
-  
+
   memcpy(prev_crc, current_crc, crc_bytes);
 }
 
@@ -963,28 +963,15 @@ bool dmdreader_init(bool return_on_no_detection) {
 
   } while (dmd_type == DMD_UNKNOWN);
 
-  // Delay is still needed when blink gets removed above.
-  // delay(1000);
-
-  // Debug blinking to indicate the detected system:
-  /*
-    for (uint8_t i = 0; i < (dmd_type * 3); i++) {
-      digitalWrite(LED_BUILTIN, HIGH);
-      delay(200);
-      digitalWrite(LED_BUILTIN, LOW);
-      delay(200);
-    }
-  */
-
   // Initialize DMD reader
   switch (dmd_type) {
     case DMD_WPC: {
       uint input_pins[] = {RDATA};
-      dmdreader_programs_init(&dmd_reader_2bpp_program,
-                              dmd_reader_2bpp_program_get_default_config,
-                              &dmd_framedetect_generic_program,
-                              dmd_framedetect_generic_program_get_default_config,
-                              input_pins, 1, 0, SDATA);
+      dmdreader_programs_init(
+          &dmd_reader_2bpp_program, dmd_reader_2bpp_program_get_default_config,
+          &dmd_framedetect_generic_program,
+          dmd_framedetect_generic_program_get_default_config, input_pins, 1, 0,
+          SDATA);
 
       // load 4096 - 1 pixels directly to TX fifo
       pio_sm_put(dmd_pio, dmd_sm, 4095);
@@ -1022,16 +1009,15 @@ bool dmdreader_init(bool return_on_no_detection) {
       source_lineoversampling = LINEOVERSAMPLING_NONE;
       source_mergeplanes = MERGEPLANES_ADD;
       break;
-    }    
+    }
 
     case DMD_WHITESTAR: {
       uint input_pins[] = {RDATA};
       dmdreader_programs_init(
-          &dmd_reader_2bpp_program,
-          dmd_reader_2bpp_program_get_default_config,
+          &dmd_reader_2bpp_program, dmd_reader_2bpp_program_get_default_config,
           &dmd_framedetect_generic_program,
-          dmd_framedetect_generic_program_get_default_config, input_pins, 1,
-          0, SDATA);
+          dmd_framedetect_generic_program_get_default_config, input_pins, 1, 0,
+          SDATA);
 
       // load 8192 - 1 pixels directly to TX fifo
       pio_sm_put(dmd_pio, dmd_sm, 8191);
@@ -1074,11 +1060,11 @@ bool dmdreader_init(bool return_on_no_detection) {
 
     case DMD_SAM: {
       uint input_pins[] = {RDATA};
-      dmdreader_programs_init(&dmd_reader_4bpp_program,
-                              dmd_reader_4bpp_program_get_default_config,
-                              &dmd_framedetect_generic_program,
-                              dmd_framedetect_generic_program_get_default_config,
-                              input_pins, 1, 0, SDATA);
+      dmdreader_programs_init(
+          &dmd_reader_4bpp_program, dmd_reader_4bpp_program_get_default_config,
+          &dmd_framedetect_generic_program,
+          dmd_framedetect_generic_program_get_default_config, input_pins, 1, 0,
+          SDATA);
 
       // load 16384 - 1 pixels directly to TX fifo
       pio_sm_put(dmd_pio, dmd_sm, 16383);
@@ -1107,7 +1093,7 @@ bool dmdreader_init(bool return_on_no_detection) {
       // we need it to sample data on the rising edge
 
       source_width = 128;
-      source_height = 32; // is actually 16, but we process as 32
+      source_height = 32;       // is actually 16, but we process as 32
       source_bitsperpixel = 4;  // recorded as 4bpp in the pio
       target_bitsperpixel = 2;  // max pixel value is 3
       // in DE-Sega, there's only one plane,
@@ -1140,7 +1126,7 @@ bool dmdreader_init(bool return_on_no_detection) {
       pio_sm_put(frame_pio, frame_sm, 2500);
 
       source_width = 128;
-      source_height = 32; // is actually 16, but we process as 32
+      source_height = 32;       // is actually 16, but we process as 32
       source_bitsperpixel = 4;  // recorded as 4bpp in the pio
       target_bitsperpixel = 2;  // max pixvalues are 0, 1, 2, 3
       // in DE-Sega, there's only one plane,
@@ -1180,8 +1166,7 @@ bool dmdreader_init(bool return_on_no_detection) {
     case DMD_SEGA_HD: {
       uint input_pins[] = {RDATA};
       dmdreader_programs_init(
-          &dmd_reader_2bpp_program,
-          dmd_reader_2bpp_program_get_default_config,
+          &dmd_reader_2bpp_program, dmd_reader_2bpp_program_get_default_config,
           &dmd_framedetect_generic_program,
           dmd_framedetect_generic_program_get_default_config, input_pins, 1, 0,
           SDATA);
@@ -1206,8 +1191,7 @@ bool dmdreader_init(bool return_on_no_detection) {
     case DMD_GOTTLIEB: {
       uint input_pins[] = {RDATA};
       dmdreader_programs_init(
-          &dmd_reader_4bpp_program,
-          dmd_reader_4bpp_program_get_default_config,
+          &dmd_reader_4bpp_program, dmd_reader_4bpp_program_get_default_config,
           &dmd_framedetect_generic_program,
           dmd_framedetect_generic_program_get_default_config, input_pins, 1, 0,
           SDATA);
@@ -1254,8 +1238,7 @@ bool dmdreader_init(bool return_on_no_detection) {
     case DMD_ISLAND: {
       uint input_pins[] = {RDATA};
       dmdreader_programs_init(
-          &dmd_reader_4bpp_program,
-          dmd_reader_4bpp_program_get_default_config,
+          &dmd_reader_4bpp_program, dmd_reader_4bpp_program_get_default_config,
           &dmd_framedetect_generic_program,
           dmd_framedetect_generic_program_get_default_config, input_pins, 1, 0,
           SDATA);
@@ -1277,8 +1260,7 @@ bool dmdreader_init(bool return_on_no_detection) {
     case DMD_HOMEPIN: {
       uint input_pins[] = {RDATA};
       dmdreader_programs_init(
-          &dmd_reader_4bpp_program,
-          dmd_reader_4bpp_program_get_default_config,
+          &dmd_reader_4bpp_program, dmd_reader_4bpp_program_get_default_config,
           &dmd_framedetect_homepin_program,
           dmd_framedetect_homepin_program_get_default_config, input_pins, 1, 0,
           SDATA);
@@ -1305,8 +1287,9 @@ bool dmdreader_init(bool return_on_no_detection) {
                               &dmd_framedetect_capcom_program,
                               dmd_framedetect_capcom_program_get_default_config,
                               input_pins, 2, 0, SDATA);
-      // Spinball uses the WPC rendering method (timings are very close actually)
-      // The Capcom framedetect method is used to find the start of a frame
+      // Spinball uses the WPC rendering method (timings are very close
+      // actually) The Capcom framedetect method is used to find the start of a
+      // frame
 
       // load 4096 - 1 pixels directly to TX fifo
       pio_sm_put(dmd_pio, dmd_sm, 4095);
@@ -1326,12 +1309,11 @@ bool dmdreader_init(bool return_on_no_detection) {
 
     case DMD_SLEIC: {
       uint input_pins[] = {DE, RDATA};
-      dmdreader_programs_init(
-          &dmd_reader_2bpp_program,
-          dmd_reader_2bpp_program_get_default_config,
-          &dmd_framedetect_sleic_program,
-          dmd_framedetect_sleic_program_get_default_config, input_pins, 2,
-          DE, SDATA);
+      dmdreader_programs_init(&dmd_reader_2bpp_program,
+                              dmd_reader_2bpp_program_get_default_config,
+                              &dmd_framedetect_sleic_program,
+                              dmd_framedetect_sleic_program_get_default_config,
+                              input_pins, 2, DE, SDATA);
 
       // load 8192 - 1 pixels directly to TX fifo
       pio_sm_put(dmd_pio, dmd_sm, 8191);
@@ -1376,12 +1358,11 @@ bool dmdreader_init(bool return_on_no_detection) {
     case DMD_ROMSTAR:
     case DMD_CAPCOM_HD: {
       uint input_pins[] = {RDATA, RCLK};
-      dmdreader_programs_init(
-          &dmd_reader_4bpp_program,
-          dmd_reader_4bpp_program_get_default_config,
-          &dmd_framedetect_capcom_program,
-          dmd_framedetect_capcom_program_get_default_config, input_pins, 2,
-          0, SDATA);
+      dmdreader_programs_init(&dmd_reader_4bpp_program,
+                              dmd_reader_4bpp_program_get_default_config,
+                              &dmd_framedetect_capcom_program,
+                              dmd_framedetect_capcom_program_get_default_config,
+                              input_pins, 2, 0, SDATA);
 
       // load 16384 - 1 pixels directly to TX fifo
       pio_sm_put(dmd_pio, dmd_sm, 16383);
@@ -1434,7 +1415,7 @@ bool dmdreader_init(bool return_on_no_detection) {
 
     // The CRC history needs to be configured here.
     // 1 for non plane systems, 2 for Gottlieb, and 3 for WPC/similar systems.
-    // Any new systems that make use of a potential different plane/history 
+    // Any new systems that make use of a potential different plane/history
     // setup -> check code below to see if it grants a desired result.
     uint8_t crc_history_count = 1;
     if (source_planehistoryperframe > 0) {
@@ -1464,8 +1445,8 @@ bool dmdreader_init(bool return_on_no_detection) {
     framebuf3 = alloc_aligned_buffer(framebuf3_bytes, 8, nullptr);
 
     dmdreader_error_blink(planebuf1 && planebuf2 && processingbuf &&
-                          framebuf1 && framebuf2 && framebuf3 &&
-                          current_crc && prev_crc);
+                          framebuf1 && framebuf2 && framebuf3 && current_crc &&
+                          prev_crc);
 
     memset(planebuf1, 0, plane_bytes);
     memset(planebuf2, 0, plane_bytes);
@@ -1490,8 +1471,8 @@ bool dmdreader_init(bool return_on_no_detection) {
   // Read a 128x16 frame but process as 128x32, so, change the number of
   // transfers at this stage to trigger a dma transfer at the right time.
   if (dmd_type == DMD_DE_X16_V1 || dmd_type == DMD_DE_X16_V2) {
-      source_dwordsperframe /= 2;
-      source_dwordsperplane /= 2;
+    source_dwordsperframe /= 2;
+    source_dwordsperplane /= 2;
   }
 
   // DMA for DMD reader

From 23a3a27e3e50bfde46d5e1a069b0c1a796a65100 Mon Sep 17 00:00:00 2001
From: Jan Vos <jjcvos@hotmail.nl>
Date: Sat, 25 Jul 2026 01:18:55 +0200
Subject: [PATCH 09/18] oops, change to the correct frame block type. CRC
 officially removed.

---
 src/dmdreader.cpp | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/src/dmdreader.cpp b/src/dmdreader.cpp
index 292f304c..47c5d877 100644
--- a/src/dmdreader.cpp
+++ b/src/dmdreader.cpp
@@ -21,7 +21,7 @@ typedef struct buf32_t {
 
 // SPI data types and header blocks
 // header block length should always be a multiple of 32bit
-#define SPI_BLOCK_PIX 0x44ee  // DMD frame
+#define SPI_BLOCK_PIX 0xcc33  // DMD frame
 
 typedef struct __attribute__((__packed__)) block_header_t {
   uint16_t block_type;  // block type
@@ -32,8 +32,7 @@ typedef struct __attribute__((__packed__)) block_pix_header_t {
   uint16_t columns;       // number of columns
   uint16_t rows;          // number of rows
   uint16_t bitsperpixel;  // bits per pixel
-  uint16_t padding;
-  uint32_t reserved;
+  uint16_t padding;       // padding bits
 } block_pix_header_t __attribute__((aligned(4)));
 
 DmdType dmd_type;

From 02cf3fed6d58041ddab1a624d8b20418aed42edd Mon Sep 17 00:00:00 2001
From: Jan Vos <jjcvos@hotmail.nl>
Date: Sat, 25 Jul 2026 02:21:02 +0200
Subject: [PATCH 10/18] remove more garbage

---
 docs/install-openocd.md               | 39 ---------------------------
 platformio.ini                        |  4 +--
 scripts/program-pbos.sh               | 15 -----------
 scripts/program-pico.sh               |  2 --
 scripts/raspberrypi-swd-dmdreader.cfg | 12 ---------
 5 files changed, 2 insertions(+), 70 deletions(-)
 delete mode 100644 docs/install-openocd.md
 delete mode 100755 scripts/program-pbos.sh
 delete mode 100755 scripts/program-pico.sh
 delete mode 100644 scripts/raspberrypi-swd-dmdreader.cfg

diff --git a/docs/install-openocd.md b/docs/install-openocd.md
deleted file mode 100644
index da97e859..00000000
--- a/docs/install-openocd.md
+++ /dev/null
@@ -1,39 +0,0 @@
-# OpenOCD
-
-To upload software to the RP2040, OpenOCD is needed.
-
-## Installation
-```
-sudo apt install automake autoconf build-essential texinfo libtool libftdi-dev libusb-1.0-0-dev
-git clone --recurse-submodules --depth 1 --branch rp2040 https://github.com/raspberrypi/openocd.git
-cd openocd/
-./bootstrap 
-./configure --enable-ftdi --enable-sysfsgpio --enable-bcm2835gpio
-make -j 4
-sudo make install
-```
-
-## Configuration
-sudo vi /usr/local/share/openocd/scripts/interface/raspberrypi-swd.cfg
-
-```
-# Use RPI GPIO pins
-adapter driver bcm2835gpio
-
-bcm2835gpio_speed_coeffs 146203 36
-
-# SWD                swclk swdio
-# Header pin numbers
-bcm2835gpio_swd_nums 23    22
-
-transport select swd
-
-adapter speed 1000
-```
-
-## Usage
-
-```
-openocd -f interface/raspberrypi-swd.cfg -f target/rp2040.cfg
-```
-
diff --git a/platformio.ini b/platformio.ini
index 956a868b..4eef6051 100644
--- a/platformio.ini
+++ b/platformio.ini
@@ -2,14 +2,14 @@
 default_envs = ppucdmd
 
 [env:ppucdmd]
-platform = https://github.com/mkalkbrenner/platform-raspberrypi#issue-112
+platform = https://github.com/maxgerhardt/platform-raspberrypi#79ce473e1a8010ed8096388690222fd2c94858a6
 framework = arduino
 board = pico
 board_build.core = earlephilhower
 board_build.filesystem_size = 0.5m
 
 [env:ppucdmd2]
-platform = https://github.com/mkalkbrenner/platform-raspberrypi#issue-112
+platform = https://github.com/maxgerhardt/platform-raspberrypi#79ce473e1a8010ed8096388690222fd2c94858a6
 framework = arduino
 board = rpipico2
 board_build.core = earlephilhower
diff --git a/scripts/program-pbos.sh b/scripts/program-pbos.sh
deleted file mode 100755
index f51f77b9..00000000
--- a/scripts/program-pbos.sh
+++ /dev/null
@@ -1,15 +0,0 @@
-#!/bin/bash
-if [ "$1" == "" ]; then
-	echo "start with $0 hostname to program RPO2040 on PBOS"
-	exit 1
-fi
-
-echo "Stopping DMDReader..."
-sshpass -p pbos scp dmdreader.elf root@$1:/firmware 
-sshpass -p pbos ssh -l root $1 'pkill dmdreader'
-sleep 5
-sshpass -p pbos ssh -l root $1 'pkill -KILL dmdreader'
-echo "Programming RP2040..."
-sshpass -p pbos ssh -l root $1 'cd /firmware; openocd -f raspberrypi-swd-dmdreader.cfg -f target/rp2040.cfg -c "program dmdreader.elf verify reset exit"'
-echo "Rebooting..."
-sshpass -p pbos ssh -l root $1 'reboot'
diff --git a/scripts/program-pico.sh b/scripts/program-pico.sh
deleted file mode 100755
index 5413957c..00000000
--- a/scripts/program-pico.sh
+++ /dev/null
@@ -1,2 +0,0 @@
-#!/bin/sh
-openocd -f raspberrypi-swd-dmdreader.cfg -f target/rp2040.cfg -c "program dmdreader.elf verify reset exit"
diff --git a/scripts/raspberrypi-swd-dmdreader.cfg b/scripts/raspberrypi-swd-dmdreader.cfg
deleted file mode 100644
index f7fe7f56..00000000
--- a/scripts/raspberrypi-swd-dmdreader.cfg
+++ /dev/null
@@ -1,12 +0,0 @@
-# Use RPI GPIO pins
-adapter driver bcm2835gpio
-
-bcm2835gpio_speed_coeffs 146203 36
-
-# SWD                swclk swdio
-# Header pin numbers
-bcm2835gpio_swd_nums 23    22
-
-transport select swd
-
-adapter speed 1000

From 0e1a04ce69717453c24997e52dca01925724deca Mon Sep 17 00:00:00 2001
From: Jan Vos <jjcvos@hotmail.nl>
Date: Mon, 27 Jul 2026 12:57:14 +0200
Subject: [PATCH 11/18] test clean exit

---
 src/dmdreader.cpp | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/src/dmdreader.cpp b/src/dmdreader.cpp
index 47c5d877..3e5aef06 100644
--- a/src/dmdreader.cpp
+++ b/src/dmdreader.cpp
@@ -221,6 +221,21 @@ void start_spi() { digitalWrite(SPI0_CS, HIGH); }
  */
 void finish_spi() { digitalWrite(SPI0_CS, LOW); }
 
+/**
+ * @brief Exit SPI by stopping the DMD pio and sending a blank dummy frame.
+ *
+ */
+void spi_clean_exit() {
+  static bool exit_executed = false;
+  if (spi_busy() || exit_executed) {
+    return;
+  }
+  pio_sm_set_enabled(dmd_pio, dmd_sm, false);
+  memset(framebuf1, 0, target_bytes);
+  spi_send_pix(framebuf1, false);
+  exit_executed = true;
+}
+
 /**
  * @brief Send a pix buffer via SPI
  *
@@ -1546,12 +1561,14 @@ void dmdreader_spi_init() {
   irq_set_enabled(DMA_IRQ_1, true);
 }
 
-bool dmdreader_spi_send() {
+bool dmdreader_spi_send(bool is_restarting) {
   if (!loopback && frame_received) {
     frame_received = false;
     spi_send_pix(framebuf_to_send, true);
 
     return true;
+  } else if (is_restarting) {
+    spi_clean_exit();
   }
 
   return false;

From 9e66ddece73a2bc3218cc4d4f49c677de5e8cb85 Mon Sep 17 00:00:00 2001
From: Jan Vos <jjcvos@hotmail.nl>
Date: Mon, 27 Jul 2026 13:05:08 +0200
Subject: [PATCH 12/18] correct some stuff

---
 src/dmdreader.cpp | 4 ++--
 src/dmdreader.h   | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/dmdreader.cpp b/src/dmdreader.cpp
index 3e5aef06..e27b741c 100644
--- a/src/dmdreader.cpp
+++ b/src/dmdreader.cpp
@@ -232,8 +232,8 @@ void spi_clean_exit() {
   }
   pio_sm_set_enabled(dmd_pio, dmd_sm, false);
   memset(framebuf1, 0, target_bytes);
-  spi_send_pix(framebuf1, false);
-  exit_executed = true;
+  memset(framebuf2, 0, target_bytes);
+  frame_received = exit_executed = true;
 }
 
 /**
diff --git a/src/dmdreader.h b/src/dmdreader.h
index 8acb6b5f..fc6460a0 100644
--- a/src/dmdreader.h
+++ b/src/dmdreader.h
@@ -46,7 +46,7 @@ enum DmdType : uint8_t {
 bool dmdreader_init(bool return_on_no_detection = false);
 
 void dmdreader_spi_init();
-bool dmdreader_spi_send();
+bool dmdreader_spi_send(bool is_restarting = false);
 
 void dmdreader_loopback_init(uint8_t *buffer1, uint8_t *buffer2, Color color);
 void dmdreader_loopback_stop();

From 7e992af5ed7259303b600d8b523fe9aec6d200d5 Mon Sep 17 00:00:00 2001
From: Jan Vos <jjcvos@hotmail.nl>
Date: Mon, 27 Jul 2026 13:19:55 +0200
Subject: [PATCH 13/18] try some debug quickly

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

diff --git a/src/dmdreader.cpp b/src/dmdreader.cpp
index e27b741c..bf7f6074 100644
--- a/src/dmdreader.cpp
+++ b/src/dmdreader.cpp
@@ -228,12 +228,15 @@ void finish_spi() { digitalWrite(SPI0_CS, LOW); }
 void spi_clean_exit() {
   static bool exit_executed = false;
   if (spi_busy() || exit_executed) {
+    Serial.printf("was busy or executed.\n");
     return;
   }
+
   pio_sm_set_enabled(dmd_pio, dmd_sm, false);
   memset(framebuf1, 0, target_bytes);
   memset(framebuf2, 0, target_bytes);
   frame_received = exit_executed = true;
+  Serial.printf("Executed! done.\n");
 }
 
 /**

From 696ec091aa6f141559ac2eb83a5d476044be79c9 Mon Sep 17 00:00:00 2001
From: Jan Vos <jjcvos@hotmail.nl>
Date: Mon, 27 Jul 2026 13:26:16 +0200
Subject: [PATCH 14/18] is too quick

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

diff --git a/src/dmdreader.cpp b/src/dmdreader.cpp
index bf7f6074..b665fb00 100644
--- a/src/dmdreader.cpp
+++ b/src/dmdreader.cpp
@@ -229,6 +229,7 @@ void spi_clean_exit() {
   static bool exit_executed = false;
   if (spi_busy() || exit_executed) {
     Serial.printf("was busy or executed.\n");
+    delay(1);
     return;
   }
 

From 14df459eeec5bfcbfa75739ffae9f756193b8e31 Mon Sep 17 00:00:00 2001
From: Jan Vos <jjcvos@hotmail.nl>
Date: Mon, 27 Jul 2026 13:28:47 +0200
Subject: [PATCH 15/18] try

---
 src/dmdreader.cpp | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/dmdreader.cpp b/src/dmdreader.cpp
index b665fb00..80b5f1f9 100644
--- a/src/dmdreader.cpp
+++ b/src/dmdreader.cpp
@@ -228,8 +228,6 @@ void finish_spi() { digitalWrite(SPI0_CS, LOW); }
 void spi_clean_exit() {
   static bool exit_executed = false;
   if (spi_busy() || exit_executed) {
-    Serial.printf("was busy or executed.\n");
-    delay(1);
     return;
   }
 
@@ -263,6 +261,7 @@ bool spi_send_pix(uint8_t *pixbuf, bool skip_when_busy) {
   spi_send_blocking((uint32_t *)&ph, sizeof(ph));
   spi_send_dma((uint32_t *)pixbuf, target_bytes);
   start_spi();
+  Serial.printf("SPI sent.\n");
 
   return true;
 }

From 90d7c3bf85ad3ca225011bab4641c57ea2dd6dfc Mon Sep 17 00:00:00 2001
From: Jan Vos <jjcvos@hotmail.nl>
Date: Mon, 27 Jul 2026 14:45:58 +0200
Subject: [PATCH 16/18] remove debug print

---
 src/dmdreader.cpp | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/src/dmdreader.cpp b/src/dmdreader.cpp
index 80b5f1f9..432487f9 100644
--- a/src/dmdreader.cpp
+++ b/src/dmdreader.cpp
@@ -222,7 +222,8 @@ void start_spi() { digitalWrite(SPI0_CS, HIGH); }
 void finish_spi() { digitalWrite(SPI0_CS, LOW); }
 
 /**
- * @brief Exit SPI by stopping the DMD pio and sending a blank dummy frame.
+ * @brief Cleanly exit SPI by stopping the DMD pio and sending a blank dummy
+ * frame.
  *
  */
 void spi_clean_exit() {
@@ -235,7 +236,6 @@ void spi_clean_exit() {
   memset(framebuf1, 0, target_bytes);
   memset(framebuf2, 0, target_bytes);
   frame_received = exit_executed = true;
-  Serial.printf("Executed! done.\n");
 }
 
 /**
@@ -261,7 +261,6 @@ bool spi_send_pix(uint8_t *pixbuf, bool skip_when_busy) {
   spi_send_blocking((uint32_t *)&ph, sizeof(ph));
   spi_send_dma((uint32_t *)pixbuf, target_bytes);
   start_spi();
-  Serial.printf("SPI sent.\n");
 
   return true;
 }

From 4139bf73f516b9333b629b4dc991a40f8e04d224 Mon Sep 17 00:00:00 2001
From: Jan Vos <jjcvos@hotmail.nl>
Date: Mon, 27 Jul 2026 17:22:02 +0200
Subject: [PATCH 17/18] Move crc updating code into their own functions + some
 comments.

---
 src/dmdreader.cpp | 58 ++++++++++++++++++++++++++++++-----------------
 1 file changed, 37 insertions(+), 21 deletions(-)

diff --git a/src/dmdreader.cpp b/src/dmdreader.cpp
index 432487f9..80aabf9c 100644
--- a/src/dmdreader.cpp
+++ b/src/dmdreader.cpp
@@ -620,12 +620,36 @@ void dmd_dma_reset() {
   dmd_set_and_enable_new_dma_target();
 }
 
+/**
+ * @brief Updates the current CRC array with the new frame CRC hash.
+ *
+ */
+void save_current_crc() {
+  if (crc_bytes >= sizeof(uint32_t)) {
+    memmove(&current_crc[0], &current_crc[sizeof(uint32_t)],
+            crc_bytes - sizeof(uint32_t));
+    memcpy(&current_crc[crc_bytes - sizeof(uint32_t)], &frame_crc,
+           sizeof(uint32_t));
+  } else {
+    memcpy(current_crc, &frame_crc, sizeof(uint32_t));
+  }
+}
+
+/**
+ * @brief Updates the previous CRC array with the current CRC array.
+ *
+ */
+void save_previous_crc() {
+  memcpy(prev_crc, current_crc, crc_bytes);
+}
+
 /**
  * @brief Handles DMD DMA requests by switching between the buffers
  *
  */
 void dmd_dma_handler() {
-  // get the frame crc by sniffing the DMA transfer at no cpu cost
+  // get the frame crc by sniffing the DMA transfer at no cpu cost.
+  // must be called before setting a new dma target!
   frame_crc = dma_hw->sniff_data;
   dma_hw->sniff_data = 0xFFFFFFFF;  // always clean after sniffing.
 
@@ -897,20 +921,13 @@ void dmd_dma_handler() {
     return;
   }
 
-  if (crc_bytes >= sizeof(uint32_t)) {
-    memmove(&current_crc[0], &current_crc[sizeof(uint32_t)],
-            crc_bytes - sizeof(uint32_t));
-    memcpy(&current_crc[crc_bytes - sizeof(uint32_t)], &frame_crc,
-           sizeof(uint32_t));
-  } else {
-    memcpy(current_crc, &frame_crc, sizeof(uint32_t));
-  }
-
+  save_current_crc();
+  // perform a comparison check to see if the current CRC bytes differ
   if (!std::is_permutation(current_crc, current_crc + crc_bytes, prev_crc)) {
     frame_received = true;
   }
 
-  memcpy(prev_crc, current_crc, crc_bytes);
+  save_previous_crc();
 }
 
 void dmdreader_error_blink(bool no_error) {
@@ -1430,28 +1447,28 @@ bool dmdreader_init(bool return_on_no_detection) {
     size_t processing_bytes = source_bytes * source_lineoversampling;
 
     // The CRC history needs to be configured here.
-    // 1 for non plane systems, 2 for Gottlieb, and 3 for WPC/similar systems.
-    // Any new systems that make use of a potential different plane/history
-    // setup -> check code below to see if it grants a desired result.
+    // 1 for non planehistory systems, 2 for Gottlieb, and 3 for WPC/similar
+    // systems. Any new systems that make use of a potential different
+    // planehistory setup: double check code below.
     uint8_t crc_history_count = 1;
     if (source_planehistoryperframe > 0) {
       if (source_planesperframe - source_planehistoryperframe == 1) {
-        // WPC and any system using a similar history plane setup
+        // WPC: planehistory is sourceplanesperframe - 1.
         crc_history_count = source_planesperframe;
       } else if (source_planesperframe % source_planehistoryperframe == 0) {
-        // Gottlieb: plane history is half the amount of total planes.
+        // Gottlieb: planehistory is half the amount of total planes.
         crc_history_count = source_planesperframe / source_planehistoryperframe;
       }
     }
     crc_bytes = crc_history_count * sizeof(uint32_t);
 
+    current_crc = alloc_aligned_buffer(crc_bytes, 4, nullptr);
+    prev_crc = alloc_aligned_buffer(crc_bytes, 4, nullptr);
     planebuf1 = alloc_aligned_buffer(plane_bytes, 4, nullptr);
     planebuf2 = alloc_aligned_buffer(plane_bytes, 4, nullptr);
     processingbuf = alloc_aligned_buffer(processing_bytes, 8, nullptr);
     framebuf1 = alloc_aligned_buffer(source_bytes, 8, nullptr);
     framebuf2 = alloc_aligned_buffer(source_bytes, 8, nullptr);
-    current_crc = alloc_aligned_buffer(crc_bytes, 4, nullptr);
-    prev_crc = alloc_aligned_buffer(crc_bytes, 4, nullptr);
     size_t framebuf3_bytes = target_bytes;
     size_t loopback_render_bytes =
         source_width * source_height * 4 / 8;  // 4bpp render buffer
@@ -1460,9 +1477,8 @@ bool dmdreader_init(bool return_on_no_detection) {
     }
     framebuf3 = alloc_aligned_buffer(framebuf3_bytes, 8, nullptr);
 
-    dmdreader_error_blink(planebuf1 && planebuf2 && processingbuf &&
-                          framebuf1 && framebuf2 && framebuf3 && current_crc &&
-                          prev_crc);
+    dmdreader_error_blink(current_crc && prev_crc && planebuf1 && planebuf2 &&
+                          processingbuf && framebuf1 && framebuf2 && framebuf3);
 
     memset(planebuf1, 0, plane_bytes);
     memset(planebuf2, 0, plane_bytes);

From 4a854879c59088984039894c8a643999e3e8e4c0 Mon Sep 17 00:00:00 2001
From: Jan Vos <jjcvos@hotmail.nl>
Date: Mon, 27 Jul 2026 17:22:32 +0200
Subject: [PATCH 18/18] oops, place here.

---
 src/dmdreader.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/dmdreader.cpp b/src/dmdreader.cpp
index 80aabf9c..872d5424 100644
--- a/src/dmdreader.cpp
+++ b/src/dmdreader.cpp
@@ -1480,14 +1480,14 @@ bool dmdreader_init(bool return_on_no_detection) {
     dmdreader_error_blink(current_crc && prev_crc && planebuf1 && planebuf2 &&
                           processingbuf && framebuf1 && framebuf2 && framebuf3);
 
+    memset(current_crc, 0, crc_bytes);
+    memset(prev_crc, 0, crc_bytes);
     memset(planebuf1, 0, plane_bytes);
     memset(planebuf2, 0, plane_bytes);
     memset(processingbuf, 0, processing_bytes);
     memset(framebuf1, 0, source_bytes);
     memset(framebuf2, 0, source_bytes);
     memset(framebuf3, 0, framebuf3_bytes);
-    memset(current_crc, 0, crc_bytes);
-    memset(prev_crc, 0, crc_bytes);
   }
 
   currentPlaneBuffer = planebuf2;