feat(slave_node): Support multi-board build for bluepill_f103rb and weact_stm32g431_core

Refactor slave_node application to support building for both bluepill_f103rb and
weact_stm32g431_core boards.

- Moved RTT-specific console and shell backend configurations from prj.conf
  into board-specific .conf files (bluepill_f103rb.conf).
- Configured USART2 as console/shell for weact_stm32g431_core.
- Added Device Tree Overlay for weact_stm32g431_core to enable USART1 for Modbus
  communication (PA9/PA10).

software/CMakeLists.txt

@@ -5,4 +5,4 @@ project(software)
 add_subdirectory(modules/modbus_server)
 add_subdirectory(modules/valve)
 add_subdirectory(modules/fwu)
-add_subdirectory(apps/hello_world)
+add_subdirectory(apps/stm32g431_tests)

software/apps/slave_node/boards/bluepill_f103rb.conf

@@ -0,0 +1,6 @@
+# Disable UART console
+CONFIG_UART_CONSOLE=n
+
+# Enable RTT console
+CONFIG_RTT_CONSOLE=y
+CONFIG_USE_SEGGER_RTT=y

software/apps/slave_node/boards/weact_stm32g431_core.overlay

@@ -0,0 +1,9 @@
+&usart1 {
+	modbus0 {
+		compatible = "zephyr,modbus-serial";
+		status = "okay";
+	};
+	status = "okay";
+    pinctrl-0 = <&usart1_tx_pa9 &usart1_rx_pa10>;
+    pinctrl-names = "default";
+};

software/apps/slave_node/prj.conf

@@ -2,13 +2,6 @@
 CONFIG_CONSOLE=y
 CONFIG_LOG=y
 
-# Disable UART console
-CONFIG_UART_CONSOLE=n
-
-# Enable RTT console
-CONFIG_RTT_CONSOLE=y
-CONFIG_USE_SEGGER_RTT=y
-
 # Enable Shell
 CONFIG_SHELL=y
 CONFIG_SHELL_BACKEND_RTT=y

software/apps/stm32g431_tests/CMakeLists.txt

@@ -0,0 +1,6 @@
+cmake_minimum_required(VERSION 3.20)
+
+find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
+project(stm32g431_tests)
+
+target_sources(app PRIVATE src/main.c)

software/apps/stm32g431_tests/prj.conf

@@ -0,0 +1,4 @@
+
+CONFIG_CONSOLE=y
+CONFIG_LOG=y
+CONFIG_UART_CONSOLE=y

software/apps/stm32g431_tests/src/main.c

@@ -0,0 +1,9 @@
+#include <zephyr/kernel.h>
+#include <zephyr/sys/printk.h>
+
+int main(void)
+{
+	printk("Hello World! %s\n", CONFIG_BOARD);
+	return 0;
+}
+