ADD minimal bootloader (main.cpp)

mbed-os-bootloader/main.cpp

@@ -0,0 +1,35 @@
+#include "mbed.h"
+
+#include "mbed_trace.h"
+#if MBED_CONF_MBED_TRACE_ENABLE
+#define TRACE_GROUP "bootloader"
+#endif // MBED_CONF_MBED_TRACE_ENABLE
+
+#if MBED_CONF_MBED_TRACE_ENABLE
+static UnbufferedSerial g_uart(CONSOLE_TX, CONSOLE_RX);
+
+// Function that directly outputs to an unbuffered serial port in blocking mode.
+static void boot_debug(const char *s) {
+    size_t len = strlen(s);
+    g_uart.write(s, len);
+    g_uart.write("\r\n", 2);
+}
+#endif
+
+int main() {
+#if MBED_CONF_MBED_TRACE_ENABLE
+    mbed_trace_init();
+    mbed_trace_print_function_set(boot_debug);
+#endif // MBED_CONF_MBED_TRACE_ENABLE
+
+    tr_debug("BikeComputer bootloader\r\n");
+
+    // at this stage we directly branch to the main application
+    void *sp = *((void **) POST_APPLICATION_ADDR + 0);  // NOLINT(readability/casting)
+    void *pc = *((void **) POST_APPLICATION_ADDR + 1);  // NOLINT(readability/casting)
+    tr_debug("Starting application at address 0x%08x (sp 0x%08x, pc 0x%08x)\r\n", POST_APPLICATION_ADDR, (uint32_t) sp, (uint32_t) pc);
+
+    mbed_start_application(POST_APPLICATION_ADDR);
+
+    return 0;
+}