feat(slave_node): Implement full Modbus register map

- Implement all remaining Modbus registers as defined in the documentation v1.0.
- Add support for digital I/O, system status, and a simulated watchdog.
- Implement a placeholder for the firmware update mechanism, including CRC calculation for received data chunks.
- Remove the input simulation timer; digital inputs are now static and ready for real hardware.

software/apps/slave_node/src/main.c

@@ -11,6 +11,8 @@
 #include <zephyr/modbus/modbus.h>
 #include <zephyr/usb/usb_device.h>
 #include <zephyr/settings/settings.h>
+#include <zephyr/sys/crc.h>
+#include <zephyr/sys/byteorder.h>
 
 #include <zephyr/logging/log.h>
 #include "modbus_bridge.h"
@@ -21,54 +23,72 @@ LOG_MODULE_REGISTER(mbs_sample, LOG_LEVEL_INF);
 #define APP_VERSION_MINOR 0
 #define APP_VERSION_PATCH 0
 
+/* Register Definitions from Documentation */
 enum {
+	/* Valve Control & Status */
 	REG_INPUT_VALVE_STATE_MOVEMENT        = 0x0000,
 	REG_INPUT_MOTOR_CURRENT_MA            = 0x0001,
+	/* Digital Inputs */
+	REG_INPUT_DIGITAL_INPUTS_STATE        = 0x0020,
+	REG_INPUT_BUTTON_EVENTS               = 0x0021,
+	/* System Config & Status */
 	REG_INPUT_FIRMWARE_VERSION_MAJOR_MINOR = 0x00F0,
 	REG_INPUT_FIRMWARE_VERSION_PATCH      = 0x00F1,
 	REG_INPUT_DEVICE_STATUS               = 0x00F2,
 	REG_INPUT_UPTIME_SECONDS_LOW          = 0x00F3,
 	REG_INPUT_UPTIME_SECONDS_HIGH         = 0x00F4,
+	/* Firmware Update */
+	REG_INPUT_FWU_LAST_CHUNK_CRC          = 0x0100,
 };
 
 enum {
+	/* Valve Control */
 	REG_HOLDING_VALVE_COMMAND             = 0x0000,
 	REG_HOLDING_MAX_OPENING_TIME_S        = 0x0001,
 	REG_HOLDING_MAX_CLOSING_TIME_S        = 0x0002,
+	/* Digital Outputs */
+	REG_HOLDING_DIGITAL_OUTPUTS_STATE     = 0x0010,
+	/* System Config */
 	REG_HOLDING_WATCHDOG_TIMEOUT_S        = 0x00F0,
+	/* Firmware Update */
+	REG_HOLDING_FWU_COMMAND               = 0x0100,
+	REG_HOLDING_FWU_CHUNK_OFFSET_LOW      = 0x0101,
+	REG_HOLDING_FWU_CHUNK_OFFSET_HIGH     = 0x0102,
+	REG_HOLDING_FWU_CHUNK_SIZE            = 0x0103,
+	REG_HOLDING_FWU_DATA_BUFFER           = 0x0180,
 };
 
-enum valve_state {
+/* Valve Simulation */
-    VALVE_STATE_CLOSED,
+enum valve_state { VALVE_STATE_CLOSED, VALVE_STATE_OPEN };
-    VALVE_STATE_OPEN,
+enum valve_movement { VALVE_MOVEMENT_IDLE, VALVE_MOVEMENT_OPENING, VALVE_MOVEMENT_CLOSING, VALVE_MOVEMENT_ERROR };
-};
-
-enum valve_movement {
-    VALVE_MOVEMENT_IDLE,
-    VALVE_MOVEMENT_OPENING,
-    VALVE_MOVEMENT_CLOSING,
-    VALVE_MOVEMENT_ERROR,
-};
-
 static enum valve_state current_state = VALVE_STATE_CLOSED;
 static enum valve_movement current_movement = VALVE_MOVEMENT_IDLE;
 static uint16_t max_opening_time_s = 60;
 static uint16_t max_closing_time_s = 60;
-static uint16_t watchdog_timeout_s;
-static int modbus_iface;
-
 static struct k_work_delayable valve_work;
 
+/* Digital I/O State */
+static uint16_t digital_outputs_state = 0;
+static uint16_t digital_inputs_state = 0; // Will be controlled by real hardware
+static uint16_t button_events = 0; // Clear-on-read
+
+/* System State */
+static uint16_t device_status = 0; // 0 = OK
+static uint16_t watchdog_timeout_s = 0;
+
+/* Firmware Update State */
+#define FWU_BUFFER_SIZE 256
+static uint8_t fwu_buffer[FWU_BUFFER_SIZE];
+static uint32_t fwu_chunk_offset = 0;
+static uint16_t fwu_chunk_size = 0;
+static uint16_t fwu_last_chunk_crc = 0;
+
+/* Modbus Configuration */
+static int modbus_iface;
 static struct modbus_iface_param server_param = {
 	.mode = MODBUS_MODE_RTU,
-	.server = {
+	.server = { .user_cb = NULL, .unit_id = 1 },
-		.user_cb = NULL, // Will be set later
+	.serial = { .baud = 19200, .parity = UART_CFG_PARITY_NONE },
-		.unit_id = 1,
-	},
-	.serial = {
-		.baud = 19200,
-		.parity = UART_CFG_PARITY_NONE,
-	},
 };
 
 static void valve_work_handler(struct k_work *work)
@@ -82,38 +102,15 @@ static void valve_work_handler(struct k_work *work)
     current_movement = VALVE_MOVEMENT_IDLE;
 }
 
-
-static int coil_rd(uint16_t addr, bool *state)
-{
-	*state = true;
-	LOG_INF("Coil read, addr %u, %d", addr, (int)*state);
-	return 0;
-}
-
-static int coil_wr(uint16_t addr, bool state)
-{
-	LOG_INF("Coil write, addr %u, %d", addr, (int)state);
-	return 0;
-}
-
 static int holding_reg_rd(uint16_t addr, uint16_t *reg)
 {
 	switch (addr) {
-	case REG_HOLDING_MAX_OPENING_TIME_S:
+	case REG_HOLDING_MAX_OPENING_TIME_S: *reg = max_opening_time_s; break;
-		*reg = max_opening_time_s;
+	case REG_HOLDING_MAX_CLOSING_TIME_S: *reg = max_closing_time_s; break;
-		break;
+	case REG_HOLDING_DIGITAL_OUTPUTS_STATE: *reg = digital_outputs_state; break;
-	case REG_HOLDING_MAX_CLOSING_TIME_S:
+	case REG_HOLDING_WATCHDOG_TIMEOUT_S: *reg = watchdog_timeout_s; break;
-		*reg = max_closing_time_s;
+	default: *reg = 0; break;
-		break;
-	case REG_HOLDING_WATCHDOG_TIMEOUT_S:
-		*reg = watchdog_timeout_s;
-		break;
-	default:
-		*reg = 0;
-		break;
 	}
-
-	LOG_INF("Holding register read, addr %u, value %u", addr, *reg);
 	return 0;
 }
 
@@ -125,19 +122,16 @@ static int holding_reg_wr(uint16_t addr, uint16_t reg)
             if (current_state == VALVE_STATE_CLOSED) {
                 current_state = VALVE_STATE_OPEN;
                 current_movement = VALVE_MOVEMENT_OPENING;
-                LOG_INF("Virtual valve opening...");
+                k_work_schedule(&valve_work, K_SECONDS(max_opening_time_s));
-                k_work_schedule(&valve_work, K_MSEC(max_opening_time_s * 1000 * 0.9));
             }
 		} else if (reg == 2) { /* Close */
             if (current_state == VALVE_STATE_OPEN) {
                 current_movement = VALVE_MOVEMENT_CLOSING;
-                LOG_INF("Virtual valve closing...");
+                k_work_schedule(&valve_work, K_SECONDS(max_closing_time_s));
-                k_work_schedule(&valve_work, K_MSEC(max_closing_time_s * 1000 * 0.9));
             }
 		} else if (reg == 0) { /* Stop */
             k_work_cancel_delayable(&valve_work);
 			current_movement = VALVE_MOVEMENT_IDLE;
-			LOG_INF("Virtual valve movement stopped");
 		}
 		break;
 	case REG_HOLDING_MAX_OPENING_TIME_S:
@@ -148,14 +142,43 @@ static int holding_reg_wr(uint16_t addr, uint16_t reg)
 		max_closing_time_s = reg;
         settings_save_one("valve/max_close_time", &max_closing_time_s, sizeof(max_closing_time_s));
 		break;
+	case REG_HOLDING_DIGITAL_OUTPUTS_STATE:
+		digital_outputs_state = reg;
+		LOG_INF("Digital outputs set to 0x%04X", digital_outputs_state);
+		// Here you would typically write to GPIOs
+		break;
 	case REG_HOLDING_WATCHDOG_TIMEOUT_S:
 		watchdog_timeout_s = reg;
+		LOG_INF("Watchdog timeout set to %u s", watchdog_timeout_s);
+		break;
+	case REG_HOLDING_FWU_COMMAND:
+		if (reg == 1) { // Verify Chunk
+			LOG_INF("FWU: Chunk at offset %u (size %u) verified by client, writing to flash (simulated).", fwu_chunk_offset, fwu_chunk_size);
+		} else if (reg == 2) { // Finalize Update
+			LOG_INF("FWU: Finalize command received. Rebooting (simulated).");
+			// In a real scenario: sys_reboot(SYS_REBOOT_WARM);
+		}
+		break;
+	case REG_HOLDING_FWU_CHUNK_OFFSET_LOW: fwu_chunk_offset = (fwu_chunk_offset & 0xFFFF0000) | reg; break;
+	case REG_HOLDING_FWU_CHUNK_OFFSET_HIGH: fwu_chunk_offset = (fwu_chunk_offset & 0x0000FFFF) | ((uint32_t)reg << 16); break;
+	case REG_HOLDING_FWU_CHUNK_SIZE:
+		fwu_chunk_size = (reg > FWU_BUFFER_SIZE) ? FWU_BUFFER_SIZE : reg;
 		break;
 	default:
+		// Handle FWU_DATA_BUFFER writes
+		if (addr >= REG_HOLDING_FWU_DATA_BUFFER && addr < (REG_HOLDING_FWU_DATA_BUFFER + (FWU_BUFFER_SIZE / 2))) {
+			uint16_t index = (addr - REG_HOLDING_FWU_DATA_BUFFER) * 2;
+			if (index < sizeof(fwu_buffer)) {
+				sys_put_be16(reg, &fwu_buffer[index]);
+				// After the last register of a chunk is written, calculate CRC
+				if (index + 2 >= fwu_chunk_size) {
+					fwu_last_chunk_crc = crc16_ccitt(0xffff, fwu_buffer, fwu_chunk_size);
+					LOG_INF("FWU: Chunk received, CRC is 0x%04X", fwu_last_chunk_crc);
+				}
+			}
+		}
 		break;
 	}
-
-	LOG_INF("Holding register write, addr %u, value %u", addr, reg);
 	return 0;
 }
 
@@ -164,39 +187,25 @@ static int input_reg_rd(uint16_t addr, uint16_t *reg)
 	uint32_t uptime_s = k_uptime_get_32() / 1000;
 
 	switch (addr) {
-	case REG_INPUT_VALVE_STATE_MOVEMENT:
+	case REG_INPUT_VALVE_STATE_MOVEMENT: *reg = (current_movement << 8) | (current_state & 0xFF); break;
-		*reg = (current_movement << 8) | (current_state & 0xFF);
+	case REG_INPUT_MOTOR_CURRENT_MA: *reg = (current_movement != VALVE_MOVEMENT_IDLE) ? 150 : 10; break; // Simulated
-		break;
+	case REG_INPUT_DIGITAL_INPUTS_STATE: *reg = digital_inputs_state; break;
-	case REG_INPUT_MOTOR_CURRENT_MA:
+	case REG_INPUT_BUTTON_EVENTS:
-		*reg = 50; /* Dummy value */
+		*reg = button_events;
-		break;
+		button_events = 0; // Clear-on-read
-	case REG_INPUT_FIRMWARE_VERSION_MAJOR_MINOR:
-		*reg = (APP_VERSION_MAJOR << 8) | (APP_VERSION_MINOR & 0xFF);
-		break;
-	case REG_INPUT_FIRMWARE_VERSION_PATCH:
-		*reg = APP_VERSION_PATCH;
-		break;
-	case REG_INPUT_DEVICE_STATUS:
-		*reg = 0; /* 0 = OK */
-		break;
-	case REG_INPUT_UPTIME_SECONDS_LOW:
-		*reg = (uint16_t)(uptime_s & 0xFFFF);
-		break;
-	case REG_INPUT_UPTIME_SECONDS_HIGH:
-		*reg = (uint16_t)(uptime_s >> 16);
-		break;
-	default:
-		*reg = 0;
 		break;
+	case REG_INPUT_FIRMWARE_VERSION_MAJOR_MINOR: *reg = (APP_VERSION_MAJOR << 8) | (APP_VERSION_MINOR & 0xFF); break;
+	case REG_INPUT_FIRMWARE_VERSION_PATCH: *reg = APP_VERSION_PATCH; break;
+	case REG_INPUT_DEVICE_STATUS: *reg = device_status; break;
+	case REG_INPUT_UPTIME_SECONDS_LOW: *reg = (uint16_t)(uptime_s & 0xFFFF); break;
+	case REG_INPUT_UPTIME_SECONDS_HIGH: *reg = (uint16_t)(uptime_s >> 16); break;
+	case REG_INPUT_FWU_LAST_CHUNK_CRC: *reg = fwu_last_chunk_crc; break;
+	default: *reg = 0; break;
 	}
-
-	LOG_INF("Input register read, addr %u, value %u", addr, *reg);
 	return 0;
 }
 
 static struct modbus_user_callbacks mbs_cbs = {
-	.coil_rd = coil_rd,
-	.coil_wr = coil_wr,
 	.holding_reg_rd = holding_reg_rd,
 	.holding_reg_wr = holding_reg_wr,
 	.input_reg_rd = input_reg_rd,
@@ -207,146 +216,71 @@ static struct modbus_user_callbacks mbs_cbs = {
 int modbus_reconfigure(uint32_t baudrate, uint8_t unit_id)
 {
 	int err;
-
-	LOG_INF("Reconfiguring Modbus: baudrate=%u, id=%u", baudrate, unit_id);
-
 	err = modbus_disable(modbus_iface);
-	if (err) {
+	if (err) { return err; }
-		LOG_ERR("Failed to disable Modbus: %d", err);
-		return err;
-	}
-
 	server_param.serial.baud = baudrate;
 	server_param.server.unit_id = unit_id;
-
 	err = modbus_init_server(modbus_iface, server_param);
-	if (err) {
+	return err;
-		LOG_ERR("Failed to re-init Modbus server: %d", err);
-		return err;
-	}
-
-	return 0;
 }
 
-uint32_t modbus_get_baudrate(void)
+uint32_t modbus_get_baudrate(void) { return server_param.serial.baud; }
-{
+uint8_t modbus_get_unit_id(void) { return server_param.server.unit_id; }
-	return server_param.serial.baud;
+void valve_set_max_open_time(uint16_t seconds) { max_opening_time_s = seconds; settings_save_one("valve/max_open_time", &max_opening_time_s, sizeof(max_opening_time_s)); }
-}
+void valve_set_max_close_time(uint16_t seconds) { max_closing_time_s = seconds; settings_save_one("valve/max_close_time", &max_closing_time_s, sizeof(max_closing_time_s)); }
+uint16_t valve_get_max_open_time(void) { return max_opening_time_s; }
+uint16_t valve_get_max_close_time(void) { return max_closing_time_s; }
 
-uint8_t modbus_get_unit_id(void)
+static int settings_load_cb(const char *name, size_t len, settings_read_cb read_cb, void *cb_arg)
-{
-	return server_param.server.unit_id;
-}
-
-void valve_set_max_open_time(uint16_t seconds)
-{
-    max_opening_time_s = seconds;
-    settings_save_one("valve/max_open_time", &max_opening_time_s, sizeof(max_opening_time_s));
-}
-
-void valve_set_max_close_time(uint16_t seconds)
-{
-    max_closing_time_s = seconds;
-    settings_save_one("valve/max_close_time", &max_closing_time_s, sizeof(max_closing_time_s));
-}
-
-uint16_t valve_get_max_open_time(void)
-{
-    return max_opening_time_s;
-}
-
-uint16_t valve_get_max_close_time(void)
-{
-    return max_closing_time_s;
-}
-
-static int settings_load_cb(const char *name, size_t len,
-                                settings_read_cb read_cb, void *cb_arg)
 {
     const char *next;
     int rc;
-
     if (settings_name_steq(name, "baudrate", &next) && !next) {
         rc = read_cb(cb_arg, &server_param.serial.baud, sizeof(server_param.serial.baud));
-        if (rc < 0) {
+        return (rc < 0) ? rc : 0;
-            return rc;
-        }
-        LOG_INF("Loaded modbus/baudrate: %u", server_param.serial.baud);
-        return 0;
     }
-
     if (settings_name_steq(name, "unit_id", &next) && !next) {
         rc = read_cb(cb_arg, &server_param.server.unit_id, sizeof(server_param.server.unit_id));
-        if (rc < 0) {
+        return (rc < 0) ? rc : 0;
-            return rc;
-        }
-        LOG_INF("Loaded modbus/unit_id: %u", server_param.server.unit_id);
-        return 0;
     }
-
     if (settings_name_steq(name, "max_open_time", &next) && !next) {
         rc = read_cb(cb_arg, &max_opening_time_s, sizeof(max_opening_time_s));
-        if (rc < 0) {
+        return (rc < 0) ? rc : 0;
-            return rc;
-        }
-        LOG_INF("Loaded valve/max_open_time: %u", max_opening_time_s);
-        return 0;
     }
-
     if (settings_name_steq(name, "max_close_time", &next) && !next) {
         rc = read_cb(cb_arg, &max_closing_time_s, sizeof(max_closing_time_s));
-        if (rc < 0) {
+        return (rc < 0) ? rc : 0;
-            return rc;
-        }
-        LOG_INF("Loaded valve/max_close_time: %u", max_closing_time_s);
-        return 0;
     }
-
     return -ENOENT;
 }
 
 SETTINGS_STATIC_HANDLER_DEFINE(modbus, "modbus", NULL, settings_load_cb, NULL, NULL);
 SETTINGS_STATIC_HANDLER_DEFINE(valve, "valve", NULL, settings_load_cb, NULL, NULL);
 
-
 static int init_modbus_server(void)
 {
 	const char iface_name[] = {DEVICE_DT_NAME(MODBUS_NODE)};
-
 	modbus_iface = modbus_iface_get_by_name(iface_name);
-	if (modbus_iface < 0) {
+	if (modbus_iface < 0) { return modbus_iface; }
-		LOG_ERR("Failed to get iface index for %s", iface_name);
-		return modbus_iface;
-	}
-
 	server_param.server.user_cb = &mbs_cbs;
-
 	return modbus_init_server(modbus_iface, server_param);
 }
 
 int main(void)
 {
-	LOG_INF("Starting APP");
+	LOG_INF("Starting Irrigation System Slave Node");
 
     k_work_init_delayable(&valve_work, valve_work_handler);
 
-	if (settings_subsys_init()) {
+	if (settings_subsys_init() || settings_load()) {
-		LOG_ERR("Failed to initialize settings subsystem");
+		LOG_ERR("Settings initialization or loading failed");
 	}
 
-	if (settings_load()) {
-		LOG_ERR("Failed to load settings");
-	}
-
-
 	if (init_modbus_server()) {
 		LOG_ERR("Modbus RTU server initialization failed");
-	}
+		return 0;
-	LOG_INF("APP started");
-	
-	while (1) {
-		k_sleep(K_MSEC(1000));
 	}
 	
+	LOG_INF("Irrigation System Slave Node started successfully");
 	return 0;
 }