From 763ba34110fe7328ec96161d268454ccf69269a2 Mon Sep 17 00:00:00 2001
From: Stanislav N Mikhailov <stas@enso.pro>
Date: Sun, 5 Apr 2026 00:21:12 +0300
Subject: [PATCH] Add ILI9341 backend and fix orientation/color settings

---
 Examples/Thermometr/CMakeLists.txt |  4 +-
 src/core/display_driver.c          | 68 +++++++++++++++++++++++++++---
 src/core/display_driver.h          |  1 +
 3 files changed, 66 insertions(+), 7 deletions(-)

diff --git a/Examples/Thermometr/CMakeLists.txt b/Examples/Thermometr/CMakeLists.txt
index 9134ab6..235290f 100644
--- a/Examples/Thermometr/CMakeLists.txt
+++ b/Examples/Thermometr/CMakeLists.txt
@@ -41,7 +41,9 @@ set(DISPLAY_PIN_CS 13)
 set(DISPLAY_PIN_DC 12)
 set(DISPLAY_PIN_RST 11)
 set(DISPLAY_PIN_BL 10)
-set(DISPLAY_TYPE DISPLAY_TYPE_ST7789)
+# Available values: DISPLAY_TYPE_ST7789, DISPLAY_TYPE_ILI9341
+set(DISPLAY_TYPE "DISPLAY_TYPE_ILI9341" CACHE STRING "Display controller backend")
+set_property(CACHE DISPLAY_TYPE PROPERTY STRINGS DISPLAY_TYPE_ST7789 DISPLAY_TYPE_ILI9341)
 
 # Pass display mapping into display backend without editing engine sources.
 target_compile_definitions(display_engine PUBLIC
diff --git a/src/core/display_driver.c b/src/core/display_driver.c
index 4feeda5..9d3c458 100644
--- a/src/core/display_driver.c
+++ b/src/core/display_driver.c
@@ -4,8 +4,6 @@
 #include "pico/stdlib.h"
 #include "hardware/spi.h"
 
-#if DISPLAY_TYPE == DISPLAY_TYPE_ST7789
-
 static inline void display_send_command(uint8_t cmd)
 {
     gpio_put(DISPLAY_PIN_DC, 0);
@@ -27,7 +25,7 @@ static inline void display_send_data_u8(uint8_t data)
     display_send_data_bytes(&data, 1);
 }
 
-static inline void st7789_set_window(uint16_t width, uint16_t height)
+static inline void display_set_window(uint16_t width, uint16_t height)
 {
     uint16_t x_end = (width > 0) ? (uint16_t)(width - 1u) : 0u;
     uint16_t y_end = (height > 0) ? (uint16_t)(height - 1u) : 0u;
@@ -46,6 +44,8 @@ static inline void st7789_set_window(uint16_t width, uint16_t height)
     display_send_data_bytes(window, sizeof(window));
 }
 
+#if DISPLAY_TYPE == DISPLAY_TYPE_ST7789
+
 void display_driver_panel_init(uint16_t width, uint16_t height)
 {
     gpio_set_function(DISPLAY_PIN_MOSI, GPIO_FUNC_SPI);
@@ -80,7 +80,7 @@ void display_driver_panel_init(uint16_t width, uint16_t height)
     display_send_command(0x3A); /* COLMOD */
     display_send_data_u8(0x55); /* RGB565 */
 
-    st7789_set_window(width, height);
+    display_set_window(width, height);
 
     display_send_command(0x21); /* INVON */
     display_send_command(0x29); /* DISPON */
@@ -89,18 +89,74 @@ void display_driver_panel_init(uint16_t width, uint16_t height)
 
 void display_driver_begin_frame_transfer(uint16_t width, uint16_t height)
 {
-    st7789_set_window(width, height);
+    display_set_window(width, height);
     display_send_command(0x2C); /* RAMWR */
 
     gpio_put(DISPLAY_PIN_DC, 1);
     gpio_put(DISPLAY_PIN_CS, 0);
 }
 
-void display_driver_end_frame_transfer(void)
+#elif DISPLAY_TYPE == DISPLAY_TYPE_ILI9341
+
+void display_driver_panel_init(uint16_t width, uint16_t height)
 {
+    gpio_set_function(DISPLAY_PIN_MOSI, GPIO_FUNC_SPI);
+    gpio_set_function(DISPLAY_PIN_SCK, GPIO_FUNC_SPI);
+
+    gpio_init(DISPLAY_PIN_CS);
+    gpio_init(DISPLAY_PIN_DC);
+    gpio_init(DISPLAY_PIN_RST);
+    gpio_init(DISPLAY_PIN_BL);
+    gpio_set_dir(DISPLAY_PIN_CS, GPIO_OUT);
+    gpio_set_dir(DISPLAY_PIN_DC, GPIO_OUT);
+    gpio_set_dir(DISPLAY_PIN_RST, GPIO_OUT);
+    gpio_set_dir(DISPLAY_PIN_BL, GPIO_OUT);
+
     gpio_put(DISPLAY_PIN_CS, 1);
+    gpio_put(DISPLAY_PIN_DC, 1);
+    gpio_put(DISPLAY_PIN_BL, 0);
+
+    gpio_put(DISPLAY_PIN_RST, 0);
+    sleep_ms(50);
+    gpio_put(DISPLAY_PIN_RST, 1);
+    sleep_ms(50);
+
+    display_send_command(0x01); /* SWRESET */
+    sleep_ms(150);
+    display_send_command(0x11); /* SLPOUT */
+    sleep_ms(150);
+
+    /*
+     * ILI9341 uses a different MADCTL layout than ST7789 for practical panel
+     * orientations; this value keeps 320x240 landscape without mirror and BGR.
+     */
+    display_send_command(0x36); /* MADCTL */
+    display_send_data_u8(0b11101000);
+
+    display_send_command(0x3A); /* PIXFMT */
+    display_send_data_u8(0x55); /* RGB565 */
+
+    display_set_window(width, height);
+
+    display_send_command(0x20); /* INVOFF */
+    display_send_command(0x29); /* DISPON */
+    gpio_put(DISPLAY_PIN_BL, 1);
+}
+
+void display_driver_begin_frame_transfer(uint16_t width, uint16_t height)
+{
+    display_set_window(width, height);
+    display_send_command(0x2C); /* RAMWR */
+
+    gpio_put(DISPLAY_PIN_DC, 1);
+    gpio_put(DISPLAY_PIN_CS, 0);
 }
 
 #else
 #error "Unsupported DISPLAY_TYPE. Add implementation in src/core/display_driver.c."
 #endif
+
+void display_driver_end_frame_transfer(void)
+{
+    gpio_put(DISPLAY_PIN_CS, 1);
+}
diff --git a/src/core/display_driver.h b/src/core/display_driver.h
index 563ed88..fafd909 100644
--- a/src/core/display_driver.h
+++ b/src/core/display_driver.h
@@ -4,6 +4,7 @@
 
 /* Display type identifiers used by DISPLAY_TYPE. */
 #define DISPLAY_TYPE_ST7789 1
+#define DISPLAY_TYPE_ILI9341 2
 
 #ifndef DISPLAY_TYPE
 #define DISPLAY_TYPE DISPLAY_TYPE_ST7789