8266 compatibility builds for older chips (another attempt t o solve #3690 and #3685)

some users have reported that releases after 0.14.0 are not working reliably. So we add a few "compat" for 8266 that try to reproduce the buildenv of 0.14.0 as much as possible.

* platform and platform_packages from 0.14.0
* not using PIO_FRAMEWORK_ARDUINO_MMU_CACHE16_IRAM48
* due to smaller IRAM, we had to move some functions back from IRAM to normal flash (may cause slowdown)

platformio.ini

@@ -11,7 +11,7 @@
 
 # CI binaries
 ; default_envs = nodemcuv2, esp8266_2m, esp01_1m_full, esp32dev, esp32_eth # ESP32 variant builds are temporarily excluded from CI due to toolchain issues on the GitHub Actions Linux environment
-default_envs = nodemcuv2, esp8266_2m, esp01_1m_full, nodemcuv2_160, esp8266_2m_160, esp01_1m_full_160, esp32dev, esp32_eth, esp32dev_audioreactive, lolin_s2_mini, esp32c3dev, esp32s3dev_8MB, esp32s3dev_8MB_PSRAM_opi
+default_envs = nodemcuv2, esp8266_2m, esp01_1m_full, nodemcuv2_compat, esp8266_2m_compat, esp01_1m_full_compat, nodemcuv2_160, esp8266_2m_160, esp01_1m_full_160, esp32dev, esp32_eth, esp32dev_audioreactive, lolin_s2_mini, esp32c3dev, esp32s3dev_8MB, esp32s3dev_8MB_PSRAM_opi
 
 # Release binaries
 ; default_envs = nodemcuv2, esp8266_2m, esp01_1m_full, esp32dev, esp32_eth, lolin_s2_mini, esp32c3dev, esp32s3dev_8MB
@@ -226,6 +226,27 @@ lib_deps =
   ESPAsyncUDP
   ${env.lib_deps}
 
+;; compatibilty flags - same as 0.14.0 which seems to work better on some 8266 boards. Not using PIO_FRAMEWORK_ARDUINO_MMU_CACHE16_IRAM48
+build_flags_compat =
+  -DESP8266
+  -DFP_IN_IROM
+  ;;-Wno-deprecated-declarations
+  -Wno-misleading-indentation
+  ;;-Wno-attributes ;; silence warnings about unknown attribute 'maybe_unused' in NeoPixelBus
+  -DPIO_FRAMEWORK_ARDUINO_ESPRESSIF_SDK22x_190703
+  -DPIO_FRAMEWORK_ARDUINO_LWIP_HIGHER_BANDWIDTH
+  -DVTABLES_IN_FLASH
+  -DMIMETYPE_MINIMAL
+  -DWLED_SAVE_IRAM ;; needed to prevent linker error
+
+;; this platform version was used for WLED 0.14.0
+platform_compat = espressif8266@4.2.0
+platform_packages_compat =
+                    platformio/toolchain-xtensa @ ~2.100300.220621 #2.40802.200502
+                    platformio/tool-esptool #@ ~1.413.0
+                    platformio/tool-esptoolpy #@ ~1.30000.0
+
+
 [esp32]
 #platform = https://github.com/tasmota/platform-espressif32/releases/download/v2.0.2.3/platform-espressif32-2.0.2.3.zip
 platform = espressif32@3.5.0
@@ -336,6 +357,13 @@ build_flags = ${common.build_flags_esp8266} -D WLED_RELEASE_NAME=ESP8266 #-DWLED
 lib_deps = ${esp8266.lib_deps}
 monitor_filters = esp8266_exception_decoder
 
+[env:nodemcuv2_compat]
+extends = env:nodemcuv2
+;; using platform version and build options from WLED 0.14.0
+platform = ${esp8266.platform_compat}
+platform_packages = ${esp8266.platform_packages_compat}
+build_flags = ${common.build_flags} ${esp8266.build_flags_compat} -D WLED_RELEASE_NAME=ESP8266_compat #-DWLED_DISABLE_2D
+
 [env:nodemcuv2_160]
 extends = env:nodemcuv2
 board_build.f_cpu = 160000000L
@@ -350,6 +378,13 @@ build_unflags = ${common.build_unflags}
 build_flags = ${common.build_flags_esp8266} -D WLED_RELEASE_NAME=ESP02
 lib_deps = ${esp8266.lib_deps}
 
+[env:esp8266_2m_compat]
+extends = env:esp8266_2m
+;; using platform version and build options from WLED 0.14.0
+platform = ${esp8266.platform_compat}
+platform_packages = ${esp8266.platform_packages_compat}
+build_flags = ${common.build_flags} ${esp8266.build_flags_compat} -D WLED_RELEASE_NAME=ESP02_compat #-DWLED_DISABLE_2D
+
 [env:esp8266_2m_160]
 extends = env:esp8266_2m
 board_build.f_cpu = 160000000L
@@ -365,6 +400,13 @@ build_flags = ${common.build_flags_esp8266} -D WLED_RELEASE_NAME=ESP01 -D WLED_D
   ; -D WLED_USE_UNREAL_MATH ;; may cause wrong sunset/sunrise times, but saves 7064 bytes FLASH and 975 bytes RAM
 lib_deps = ${esp8266.lib_deps}
 
+[env:esp01_1m_full_compat]
+extends = env:esp01_1m_full
+;; using platform version and build options from WLED 0.14.0
+platform = ${esp8266.platform_compat}
+platform_packages = ${esp8266.platform_packages_compat}
+build_flags = ${common.build_flags} ${esp8266.build_flags_compat} -D WLED_RELEASE_NAME=ESP01_compat -D WLED_DISABLE_OTA #-DWLED_DISABLE_2D
+
 [env:esp01_1m_full_160]
 extends = env:esp01_1m_full
 board_build.f_cpu = 160000000L

wled00/FX_2Dfcn.cpp

@@ -163,14 +163,14 @@ void WS2812FX::setUpMatrix() {
 #ifndef WLED_DISABLE_2D
 
 // XY(x,y) - gets pixel index within current segment (often used to reference leds[] array element)
-uint16_t IRAM_ATTR Segment::XY(uint16_t x, uint16_t y)
+uint16_t IRAM_ATTR_YN Segment::XY(uint16_t x, uint16_t y)
 {
   uint16_t width  = virtualWidth();   // segment width in logical pixels (can be 0 if segment is inactive)
   uint16_t height = virtualHeight();  // segment height in logical pixels (is always >= 1)
   return isActive() ? (x%width) + (y%height) * width : 0;
 }
 
-void IRAM_ATTR Segment::setPixelColorXY(int x, int y, uint32_t col)
+void IRAM_ATTR_YN Segment::setPixelColorXY(int x, int y, uint32_t col)
 {
   if (!isActive()) return; // not active
   if (x >= virtualWidth() || y >= virtualHeight() || x<0 || y<0) return;  // if pixel would fall out of virtual segment just exit

wled00/FX_fcn.cpp

@@ -145,6 +145,7 @@ Segment& Segment::operator= (Segment &&orig) noexcept {
 }
 
 bool Segment::allocateData(size_t len) {
+  if (len == 0) return false; // nothing to do
   if (data && _dataLen >= len) {          // already allocated enough (reduce fragmentation)
     if (call == 0) memset(data, 0, len);  // erase buffer if called during effect initialisation
     return true;
@@ -659,7 +660,7 @@ uint16_t Segment::virtualLength() const {
   return vLength;
 }
 
-void IRAM_ATTR Segment::setPixelColor(int i, uint32_t col)
+void IRAM_ATTR_YN Segment::setPixelColor(int i, uint32_t col)
 {
   if (!isActive()) return; // not active
 #ifndef WLED_DISABLE_2D

wled00/const.h

@@ -540,4 +540,12 @@
   #define HW_PIN_MISOSPI MISO
 #endif
 
+// IRAM_ATTR for 8266 with 32Kb IRAM causes error: section `.text1' will not fit in region `iram1_0_seg'
+// this hack removes the IRAM flag for some 1D/2D functions - somewhat slower, but it solves problems with some older 8266 chips
+#ifdef WLED_SAVE_IRAM
+  #define IRAM_ATTR_YN
+#else
+  #define IRAM_ATTR_YN IRAM_ATTR
+#endif
+
 #endif