Add wait for serial characters to transmit before deleting serial object.

Author: jeremybrodt

features/unsupported/tests/mbed/echo/main.cpp

@@ -15,6 +15,7 @@ int main() {
     MBED_HOSTTEST_SELECT(echo);
     MBED_HOSTTEST_DESCRIPTION(Serial Echo at 115200);
     MBED_HOSTTEST_START("MBED_A9");
+    wait(0.5);  // wait for characters to finish transmitting
 
     Serial pc(TXPIN, RXPIN);
     pc.baud(115200);

features/unsupported/tests/mbed/serial_nc_rx/main.cpp

@@ -15,6 +15,7 @@ int main() {
     // This should be true, sync the start of test
     if (c == 'S') {
         pc->printf("RX OK - Start NC test\r\n");
+        wait(0.25);  // wait for characters to finish transmitting
 
         // disconnect TX and  get char
         delete pc;
@@ -25,11 +26,13 @@ int main() {
             delete pc;
             pc = new Serial(USBTX, NC);
             pc->printf("RX OK - Expected\r\n");
+            wait(0.25);  // wait for characters to finish transmitting
 
             c = pc->getc();
             // This should be false/not get here
             if (c == 'U') {
                 pc->printf("RX OK - Unexpected\r\n");
+                wait(0.25);  // wait for characters to finish transmitting
             }
         }
         delete pc;

features/unsupported/tests/mbed/serial_nc_tx/main.cpp

@@ -17,15 +17,16 @@ int main() {
     if (c == 'S') {
       Serial *pc = new Serial(USBTX, NC);
       pc->printf("TX OK - Expected\r\n");
+      wait(0.5);  // wait for characters to finish transmitting
+
       delete pc;
 
       pc = new Serial(NC, USBRX);
       pc->printf("TX OK - Unexpected\r\n");
+      wait(0.5);  // wait for characters to finish transmitting
       delete pc;
     }
 
-
-
     while (1) {
     }
 }