add Chapter07

Chapter07/error_handling/app/src/main.cpp

@@ -0,0 +1,30 @@
+#include <cstdint>
+#include <cstdio>
+
+#include <stm32f072xb.h>
+
+#include <hal.hpp>
+#include <uart_stm32.hpp>
+
+#include <retarget.hpp>
+
+
+int main()
+{
+    hal::init();
+
+    hal::uart_stm32 uart(USART2);
+    uart.init();
+
+    uart.write("Hi from main function!\r\n");
+
+    retarget::set_stdio_uart(&uart);
+
+    printf("Printing using printf\r\n");
+    
+    printf("PC: 0x%08lX\r\n", hal::get_pc());
+
+    while(true)
+    {
+    }
+}