added tud_cdc_write_str, tu_fifo only use mutex for RTOS config

examples/device/nrf52840_freertos/segger/nrf5x_freertos.emProject

@@ -32,12 +32,6 @@
       target_reset_script="Reset();"
       target_script_file="$(ProjectDir)/nRF_Target.js"
       target_trace_initialize_script="EnableTrace("$(TraceInterfaceType)")" />
-    <folder Name="RTT Files">
-      <file file_name="SEGGER_RTT.c" />
-      <file file_name="SEGGER_RTT.h" />
-      <file file_name="SEGGER_RTT_Conf.h" />
-      <file file_name="SEGGER_RTT_SES.c" />
-    </folder>
     <folder Name="Script Files">
       <file file_name="nRF_Target.js">
         <configuration Name="Common" file_type="Reset Script" />
@@ -60,6 +54,12 @@
       <file file_name="../src/msc_flash_qspi.c" />
       <file file_name="../src/msc_app.c" />
       <file file_name="../src/msc_app.h" />
+      <folder Name="segger_rtt">
+        <file file_name="../src/segger_rtt/SEGGER_RTT.c" />
+        <file file_name="../src/segger_rtt/SEGGER_RTT_Conf.h" />
+        <file file_name="../src/segger_rtt/SEGGER_RTT.h" />
+        <file file_name="../src/segger_rtt/SEGGER_RTT_SES.c" />
+      </folder>
     </folder>
     <folder Name="hw">
       <folder Name="bsp">

examples/device/nrf52840_freertos/src/main.c

@@ -101,18 +101,32 @@ void cdc_task(void* params)
   while ( 1 )
   {
     // connected and there are data available
-    if ( tud_mounted() && tud_cdc_available() )
+    if ( tud_cdc_connected() )
     {
-      uint8_t buf[64];
+      if ( tud_cdc_available() )
+      {
+        uint8_t buf[64];
 
-      // read and echo back
-      uint32_t count = tud_cdc_read(buf, sizeof(buf));
+        // read and echo back
+        uint32_t count = tud_cdc_read(buf, sizeof(buf));
+
+        tud_cdc_write(buf, count);
+      }
 
-      tud_cdc_write(buf, count);
       tud_cdc_write_flush();
     }
+  }
+}
 
-    taskYIELD();
+void tud_cdc_line_state_cb(uint8_t itf, bool dtr, bool rts)
+{
+  (void) itf;
+
+  // connected
+  if ( dtr && rts )
+  {
+    // print greeting
+    tud_cdc_write_str("tinyusb usb cdc\n");
   }
 }
 #endif

examples/device/nrf52840_freertos/src/tusb_config.h

@@ -55,7 +55,7 @@
 
 /*------------- RTOS -------------*/
 #define CFG_TUSB_OS                 OPT_OS_FREERTOS
-#define CFG_TUD_TASK_PRIO           (configMAX_PRIORITIES-3)
+#define CFG_TUD_TASK_PRIO           (configMAX_PRIORITIES-1)
 //#define CFG_TUD_TASK_QUEUE_SZ     16
 //#define CFG_TUD_TASK_STACK_SZ     150