diff --git a/README.md b/README.md
index 846211d..0a13540 100644
--- a/README.md
+++ b/README.md
@@ -52,10 +52,12 @@ All code is **pure ESP-IDF v5.x (C) / FreeRTOS** — no Arduino.
 | **MFRC522** | SDA (CS) | **5** | dedicated chip select |
 | | RST | **22** | hard reset |
 | | 3.3V / GND | — | feed from board 3.3V rail |
-| **ST7789** | CS | **15** | dedicated chip select |
-| | DC (A0) | **2** | data/command |
+| **ST7789** (7-pin) | CS | **15** | dedicated chip select |
+| | DC | **2** | data/command |
 | | RST | **4** | panel reset |
-| | LED | 3.3V or 5V | optional backlight pin |
+| | SDA | **23** | shared MOSI (data) |
+| | SCL | **18** | shared SCK (clock) |
+| | VCC / GND | 3.3V / GND | panel power (no separate LED pin) |
 | **EC11** | CLK | **32** | interrupt input, pull-up |
 | | DT | **33** | quadrature B |
 | | SW | **25** | button, active low, pull-up |
@@ -67,17 +69,24 @@ All code is **pure ESP-IDF v5.x (C) / FreeRTOS** — no Arduino.
 ```
         ESP32-WROOM-32
   ┌────────────────────────────┐
-  │ 3V3  18 ──── SCK ───────┤ MFRC522  5 ── SDA(CS)  22 ── RST
-  │ GND  23 ──── MOSI ──────┤ (SPI)    3V3/GND
-  │       19 ──── MISO ─────┤
-  │       15 ──── CS ───────┤ ST7789   2 ── DC  4 ── RST
-  │       4 ─────────────────┤ (SPI)
-  │       32 ── CLK ─────────┤ EC11     33 ── DT  25 ── SW/GND
-  │       27 ── Din ─────────┤ WS2812B  (5V + GND)
-  │       14 ── SIG ─────────┤ Buzzer   (GND)
+  │ 3V3  18 ── SCK ──┐         │
+  │ GND  23 ── MOSI ─┼─────┐   │
+  │       19 ── MISO ─┘     │   │
+  │        5 ── SDA ───────┤ MFRC522 22 ── RST
+  │       22 ── RST ───────┤        3V3/GND
+  │       15 ── CS ────────┤ ST7789 (7-pin)
+  │        2 ── DC ────────┤   SDA <-> MOSI, SCL <-> SCK
+  │        4 ── RST ───────┤   VCC = 3V3, GND = GND
+  │       32 ── CLK ────────┤ EC11   33 ── DT  25 ── SW/GND
+  │       27 ── Din ────────┤ WS2812B  (5V + GND)
+  │       14 ── SIG ────────┤ Buzzer   (GND)
   └────────────────────────────┘
 ```
 
+> **7-pin ST7789 wiring recap:** connect the display's **SCL → ESP32 GPIO 18**,
+> **SDA → GPIO 23**, **CS → 15**, **DC → 2**, **RST → 4**, **VCC → 3.3V**,
+> **GND → GND**. The MFRC522 taps the same SCL/SDA lines (its own CS is GPIO 5).
+
 - Keep SPI signal runs short (< 10 cm) for reliable 20 MHz display transfers.
 - NTAG213/215 FPC stickers need to sit flat and close to the MFRC522 antenna.
 - The **WS2812B** draws up to ~60 mA; power it from the 5V rail, never from a GPIO.
diff --git a/main/hw_pins.h b/main/hw_pins.h
index 994ecf0..d043f8f 100644
--- a/main/hw_pins.h
+++ b/main/hw_pins.h
@@ -11,17 +11,20 @@
 #include "hal/gpio_types.h"
 #include "driver/spi_master.h"
 
-/* Shared SPI2_HOST (VSPI) bus */
+/* Shared SPI2_HOST (VSPI) bus.
+ * NOTE: on 7-pin ST7789 modules, the display labels these SDA (MOSI) and
+ * SCL (SCK) - they tap the SAME shared bus as the MFRC522. */
 #define HW_SPI_HOST        (SPI2_HOST)
-#define HW_SPI_SCK_GPIO    (GPIO_NUM_18)
-#define HW_SPI_MOSI_GPIO   (GPIO_NUM_23)
-#define HW_SPI_MISO_GPIO   (GPIO_NUM_19)
+#define HW_SPI_SCK_GPIO    (GPIO_NUM_18)   /* display SCL + MFRC522 SCK */
+#define HW_SPI_MOSI_GPIO   (GPIO_NUM_23)   /* display SDA + MFRC522 MOSI */
+#define HW_SPI_MISO_GPIO   (GPIO_NUM_19)   /* MFRC522 MISO only */
 
 /* MFRC522 RFID reader */
 #define HW_RC522_CS_GPIO   (GPIO_NUM_5)
 #define HW_RC522_RST_GPIO  (GPIO_NUM_22)
 
-/* ST7789 display */
+/* ST7789 display - 7-pin breakout: CS / DC / RST / SDA / SCL / GND / VCC.
+ * SDA and SCL share the SPI bus above (SCL=HW_SPI_SCK, SDA=HW_SPI_MOSI). */
 #define HW_LCD_CS_GPIO     (GPIO_NUM_15)
 #define HW_LCD_DC_GPIO     (GPIO_NUM_2)
 #define HW_LCD_RST_GPIO    (GPIO_NUM_4)