feat(shell): Add commands to configure Modbus

- Implement a new 'modbus' command in the shell.
- Add sub-commands 'set_baud', 'set_id', and 'show'.
- Add validation for baud rate and slave ID inputs.
- The new parameters are applied to the Modbus server at runtime, allowing for live reconfiguration of the communication settings.
- The shell backend is set to RTT.

software/apps/slave_node/CMakeLists.txt

@@ -6,4 +6,4 @@ list(APPEND BOARD_ROOT ${CMAKE_CURRENT_SOURCE_DIR}/../..)
 find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
 project(slave_node)
 
-target_sources(app PRIVATE src/main.c)
+target_sources(app PRIVATE src/main.c src/shell_modbus.c)

software/apps/slave_node/boards/bluepill_f103rb.overlay

@@ -1,7 +1,7 @@
 / {
     chosen {
         zephyr,console = &rtt;
-        zephyr,shell-uart = &rtt; // If using shell
+        zephyr,shell = &rtt;
     };
 
     rtt: rtt {

software/apps/slave_node/prj.conf

@@ -9,6 +9,10 @@ CONFIG_UART_CONSOLE=n
 CONFIG_RTT_CONSOLE=y
 CONFIG_USE_SEGGER_RTT=y
 
+# Enable Shell
+CONFIG_SHELL=y
+CONFIG_SHELL_BACKEND_RTT=y
+
 # Config modbus
 CONFIG_UART_INTERRUPT_DRIVEN=y
 CONFIG_MODBUS=y

software/apps/slave_node/src/main.c

@@ -12,6 +12,8 @@
 #include <zephyr/usb/usb_device.h>
 
 #include <zephyr/logging/log.h>
+#include "modbus_bridge.h"
+
 LOG_MODULE_REGISTER(mbs_sample, LOG_LEVEL_INF);
 
 #define APP_VERSION_MAJOR 1
@@ -32,6 +34,20 @@ enum {
 
 
 static uint16_t watchdog_timeout_s;
+static int modbus_iface;
+
+static struct modbus_iface_param server_param = {
+	.mode = MODBUS_MODE_RTU,
+	.server = {
+		.user_cb = NULL, // Will be set later
+		.unit_id = 1,
+	},
+	.serial = {
+		.baud = 19200,
+		.parity = UART_CFG_PARITY_NONE,
+	},
+};
+
 
 static int coil_rd(uint16_t addr, bool *state)
 {
@@ -112,33 +128,56 @@ static struct modbus_user_callbacks mbs_cbs = {
 	.input_reg_rd = input_reg_rd,
 };
 
-const static struct modbus_iface_param server_param = {
-	.mode = MODBUS_MODE_RTU,
-	.server = {
-		.user_cb = &mbs_cbs,
-		.unit_id = 1,
-	},
-	.serial = {
-		.baud = 19200,
-		.parity = UART_CFG_PARITY_NONE,
-	},
-};
-
 #define MODBUS_NODE DT_COMPAT_GET_ANY_STATUS_OKAY(zephyr_modbus_serial)
 
+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) {
+		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) {
+		LOG_ERR("Failed to re-init Modbus server: %d", err);
+		return err;
+	}
+
+	return 0;
+}
+
+uint32_t modbus_get_baudrate(void)
+{
+	return server_param.serial.baud;
+}
+
+uint8_t modbus_get_unit_id(void)
+{
+	return server_param.server.unit_id;
+}
+
+
 static int init_modbus_server(void)
 {
 	const char iface_name[] = {DEVICE_DT_NAME(MODBUS_NODE)};
-	int iface;
 
-	iface = modbus_iface_get_by_name(iface_name);
+	modbus_iface = modbus_iface_get_by_name(iface_name);
-
+	if (modbus_iface < 0) {
-	if (iface < 0) {
 		LOG_ERR("Failed to get iface index for %s", iface_name);
-		return iface;
+		return modbus_iface;
 	}
 
-	return modbus_init_server(iface, server_param);
+	server_param.server.user_cb = &mbs_cbs;
+
+	return modbus_init_server(modbus_iface, server_param);
 }
 
 int main(void)

software/apps/slave_node/src/modbus_bridge.h

@@ -0,0 +1,27 @@
+#ifndef MODBUS_BRIDGE_H
+#define MODBUS_BRIDGE_H
+
+#include <stdint.h>
+
+/**
+ * @brief Reconfigures the Modbus server with new parameters.
+ *
+ * @param baudrate New baudrate.
+ * @param unit_id New slave unit ID.
+ * @return 0 on success, negative error code on failure.
+ */
+int modbus_reconfigure(uint32_t baudrate, uint8_t unit_id);
+
+/**
+ * @brief Gets the currently active Modbus baudrate.
+ * @return The current baudrate.
+ */
+uint32_t modbus_get_baudrate(void);
+
+/**
+ * @brief Gets the currently active Modbus slave unit ID.
+ * @return The current slave unit ID.
+ */
+uint8_t modbus_get_unit_id(void);
+
+#endif // MODBUS_BRIDGE_H

software/apps/slave_node/src/shell_modbus.c

@@ -0,0 +1,79 @@
+#include <zephyr/shell/shell.h>
+#include <stdlib.h>
+#include "modbus_bridge.h"
+
+static int cmd_modbus_set_baud(const struct shell *sh, size_t argc, char **argv)
+{
+	if (argc != 2) {
+		shell_error(sh, "Usage: set_baud <baudrate>");
+		return -EINVAL;
+	}
+
+	uint32_t new_baud = (uint32_t)strtoul(argv[1], NULL, 10);
+	const uint32_t valid_baud_rates[] = {1200, 2400, 4800, 9600, 19200, 38400, 57600, 115200};
+	bool is_valid = false;
+
+	for (int i = 0; i < ARRAY_SIZE(valid_baud_rates); i++) {
+		if (new_baud == valid_baud_rates[i]) {
+			is_valid = true;
+			break;
+		}
+	}
+
+	if (!is_valid) {
+		char error_msg[128];
+		int offset = snprintf(error_msg, sizeof(error_msg), "Invalid baudrate. Valid rates are: ");
+		for (int i = 0; i < ARRAY_SIZE(valid_baud_rates); i++) {
+			offset += snprintf(error_msg + offset, sizeof(error_msg) - offset, "%u ", valid_baud_rates[i]);
+		}
+		shell_error(sh, "%s", error_msg);
+		return -EINVAL;
+	}
+
+	if (modbus_reconfigure(new_baud, modbus_get_unit_id()) != 0) {
+		shell_error(sh, "Failed to apply new baudrate");
+	} else {
+		shell_print(sh, "Modbus baudrate set to: %u", new_baud);
+	}
+
+	return 0;
+}
+
+static int cmd_modbus_set_id(const struct shell *sh, size_t argc, char **argv)
+{
+	if (argc != 2) {
+		shell_error(sh, "Usage: set_id <slave_id>");
+		return -EINVAL;
+	}
+
+	uint32_t new_id = (uint32_t)strtoul(argv[1], NULL, 10);
+	if (new_id == 0 || new_id > 247) {
+		shell_error(sh, "Invalid slave ID: %s. Must be between 1 and 247.", argv[1]);
+		return -EINVAL;
+	}
+
+	if (modbus_reconfigure(modbus_get_baudrate(), (uint8_t)new_id) != 0) {
+		shell_error(sh, "Failed to apply new slave ID");
+	} else {
+		shell_print(sh, "Modbus slave ID set to: %u", (uint8_t)new_id);
+	}
+
+	return 0;
+}
+
+static int cmd_modbus_show(const struct shell *sh, size_t argc, char **argv)
+{
+	shell_print(sh, "Current Modbus Configuration:");
+	shell_print(sh, "  Baudrate: %u", modbus_get_baudrate());
+	shell_print(sh, "  Slave ID: %u", modbus_get_unit_id());
+	return 0;
+}
+
+SHELL_STATIC_SUBCMD_SET_CREATE(sub_modbus_cmds,
+	SHELL_CMD(set_baud, NULL, "Set Modbus baudrate", cmd_modbus_set_baud),
+	SHELL_CMD(set_id,   NULL, "Set Modbus slave ID", cmd_modbus_set_id),
+	SHELL_CMD(show,     NULL, "Show current Modbus configuration", cmd_modbus_show),
+	SHELL_SUBCMD_SET_END
+);
+
+SHELL_CMD_REGISTER(modbus, &sub_modbus_cmds, "Modbus configuration", NULL);