1 files changed, 52 insertions, 0 deletions
diff --git a/firmware/c1224/include/board_pins.h b/firmware/c1224/include/board_pins.h
new file mode 100644
index 0000000..1422335
--- /dev/null
+++ b/firmware/c1224/include/board_pins.h
@@ -0,0 +1,52 @@
+/**
+ * T-Modem-c1224 pin map (service Pico — not softmodem).
+ * Frozen copper intent (v0.25 schematic) reused as planning default for 180×180.
+ * GP14/GP15 = unused mux placeholders for v1.0 (single-XTAL; stuff matches image).
+ */
+#ifndef C1224_BOARD_PINS_H
+#define C1224_BOARD_PINS_H
+
+#include <stdint.h>
+#include <stdbool.h>
+
+/* I2C LCD (shared-kit class; level-shifted on board) */
+#define PIN_I2C_SDA           0  /* GP0 */
+#define PIN_I2C_SCL           1  /* GP1 */
+#define I2C_LCD_BAUDRATE      100000
+#define I2C_LCD_ADDR_DEFAULT  0x27  /* common PCF8574 backpack; probe may fail → log-only */
+
+/* Modem chip digital (TCM3105-class) — Pico does NOT generate AFSK */
+#define PIN_MODEM_TXD         6  /* GP6 → chip TXD */
+#define PIN_MODEM_RXD         7  /* GP7 ← chip RXD → Packet UI sense (required · status only) */
+#define PIN_MODEM_CDT         8  /* GP8 ← chip CDT → Signal/RX (required) */
+
+/* PTT keying: Pico GPIO → OC → radio PTT (USB CDC service). Not the TX LED. */
+#define PIN_PTT_DRV           9  /* GP9 · required for USB PTT ON */
+
+/*
+ * Status LEDs (c1224 copper — active-high source via series R; LED cathode = GND).
+ * LED_PWR is NOT a GPIO: +5V_OR → R_LED1 → LED_PWR → GND (rail Power indicator).
+ *
+ * Settled UI (2026-07-26):
+ *   - Dual sense REQUIRED: CDT→GP8 Signal/RX · RXD→GP7 Packet (status only, not data bridge).
+ *   - CDT = carrier/tone · RXD activity ≠ full AX.25 decode.
+ *   - LED_PTT (GP10) = OPTIONAL/SPARE — not required product TX indicator.
+ *   - Display TX optional; PTT keying GPIO (GP9) stays separate from LED_PTT.
+ *   - LED_TXRX = spare/activity.
+ */
+#define PIN_LED_PTT           10 /* GP10 · LED_PTT_N · optional/spare (not required TX LED) */
+#define PIN_LED_DCD           11 /* GP11 · LED_DCD_N · optional RX mirror of CDT */
+#define PIN_LED_TXRX          12 /* GP12 · LED_TXRX_N · spare / optional activity */
+
+/*
+ * Crystal mux placeholders — UNUSED for v1.0.
+ * Product: one crystal stuffed matching flash (Y1 4.4336 / Y2 6.5536).
+ * Dual/mux path abandoned; crystal_steer is a no-op.
+ * Optional keep defines if mux ever returns later.
+ */
+#define PIN_XTAL_SEL_A        14 /* GP14 — unused v1.0 */
+#define PIN_XTAL_SEL_B        15 /* GP15 — unused v1.0 */
+
+void board_pins_init(void);
+
+#endif /* C1224_BOARD_PINS_H */