Add Phase 0 RS-232 characterization harness and test firmware with cli

src/board_pins.h

@@ -0,0 +1,33 @@
+#pragma once
+
+#include "driver/gpio.h"
+#include "driver/uart.h"
+
+/*
+ * Hardware profile: ESP32-S3-DevKitC-1-compatible N16R8 board connected to
+ * the Adafruit MAX3243 full-pinout RS-232 breakout (product 5988).
+ *
+ * Keep these definitions in one place so future board profiles can select a
+ * different pin map without scattering hardware assumptions through drivers.
+ */
+#define BOARD_RGB_LED_GPIO GPIO_NUM_48
+
+#define RS232_UART_PORT UART_NUM_1
+#define RS232_TX_GPIO GPIO_NUM_17
+#define RS232_RX_GPIO GPIO_NUM_18
+#define RS232_RTS_GPIO GPIO_NUM_15
+#define RS232_CTS_GPIO GPIO_NUM_16
+
+#define RS232_DTR_GPIO GPIO_NUM_7
+#define RS232_DSR_GPIO GPIO_NUM_5
+#define RS232_DCD_GPIO GPIO_NUM_4
+#define RS232_RI_GPIO GPIO_NUM_6
+
+#define RS232_VALID_GPIO GPIO_NUM_8
+
+/*
+ * Adafruit labels this pin OFF, but it is connected to the MAX3243
+ * active-low !FORCEOFF input. Releasing the open-drain GPIO enables the
+ * transceiver through the breakout's pull-up; driving it low disables it.
+ */
+#define RS232_FORCE_OFF_N_GPIO GPIO_NUM_9