[ion] Fix USART communication: wait for transmission done in writeLine

ion/include/ion/console.h

@@ -10,6 +10,7 @@ char readChar();
 // The lines are NULL-terminated
 void writeLine(const char * line);
 void readLine(char * line, int maxLineLength);
+bool transmissionDone();
 
 }
 }

ion/src/device/shared/drivers/console.cpp

@@ -18,9 +18,14 @@ char readChar() {
 }
 
 void writeChar(char c) {
+  Config::Port.TDR()->set(c);
+  // Wait until the write is done
   while (Config::Port.SR()->getTXE() == 0) {
   }
-  Config::Port.TDR()->set(c);
+}
+
+bool transmissionDone() {
+  return Config::Port.SR()->getTC() == 1;
 }
 
 }

ion/src/device/shared/regs/usart.h

@@ -13,6 +13,7 @@ public:
   class SR : Register32 {
   public:
     REGS_BOOL_FIELD(RXNE, 5);
+    REGS_BOOL_FIELD(TC, 6);
     REGS_BOOL_FIELD(TXE, 7);
   };
 

ion/src/shared/console_line.cpp

@@ -5,6 +5,7 @@ namespace Console {
 
 char readChar();
 void writeChar(char c);
+bool transmissionDone();
 
 void writeLine(const char * line) {
   while (*line != 0) {
@@ -12,6 +13,8 @@ void writeLine(const char * line) {
   }
   writeChar('\r');
   writeChar('\n');
+  while (!transmissionDone()) {
+  }
 }
 
 void readLine(char * line, int maxLineLength) {

ion/src/shared/console_stdio.cpp

@@ -13,5 +13,10 @@ void writeChar(char c) {
   fflush(stdout);
 }
 
+bool transmissionDone() {
+  // Always true because we flush after each writeChar
+  return true;
+}
+
 }
 }