Workaround for Capture startup hang (#1285)

* Attempt to fix Capture startup hang

* Pump baseband_queue on M4 startup

* Synchronization experiment

* Moved SpectrumCapture member, better hang detection for M0

* Prevent execute from working on members until class has been initialized.

* Formatting

* Remove workaround.

* Rebase on next

firmware/baseband/event_m4.cpp

@@ -19,21 +19,18 @@
  * Boston, MA 02110-1301, USA.
  */
 
-#include "event_m4.hpp"
-#include "debug.hpp"
-
-#include "portapack_shared_memory.hpp"
-
-#include "message_queue.hpp"
-
 #include "ch.h"
-
+#include "debug.hpp"
+#include "event_m4.hpp"
 #include "lpc43xx_cpp.hpp"
-using namespace lpc43xx;
+#include "message_queue.hpp"
+#include "portapack_shared_memory.hpp"
 
 #include <cstdint>
 #include <array>
 
+using namespace lpc43xx;
+
 extern "C" {
 
 CH_IRQ_HANDLER(MAPP_IRQHandler) {
@@ -61,6 +58,10 @@ void EventDispatcher::run() {
 
     lpc43xx::creg::m0apptxevent::enable();
 
+    // Indicate to the M0 thread that
+    // M4 is ready to receive message events.
+    shared_memory.set_baseband_ready();
+
     while (is_running) {
         const auto events = wait();
         dispatch(events);