HID LED patch to stop flashing on UART poll

This happens in WebUSB polling the UART for reads and the returned length 0 meaning no data

source/board/microbit.c

@@ -20,7 +20,8 @@
  */
 #include "fsl_device_registers.h"
 #include "IO_Config.h"
-
+#include "DAP.h"
+#include "RTL.h"
 // URL_NAME and DRIVE_NAME must be 11 characters excluding
 // the null terminated character
 // Note - 4 byte alignemnt required as workaround for ARMCC compiler bug with weak references
@@ -76,3 +77,12 @@ void prerun_board_config(void) {
     mb_version_t board_version = (mb_version_t)read_board_type_pin();
     set_board_id(board_version);
 }
+
+// USB HID override function return 1 if the activity is trivial or response is null 
+uint8_t usbd_hid_no_activity(U8 *buf)
+{
+    if(buf[0] == ID_DAP_Vendor3 &&  buf[1] == 0)
+        return 1;
+    else
+        return 0;
+}

source/daplink/cmsis-dap/usbd_user_hid.c

@@ -103,9 +103,17 @@ int usbd_hid_get_report(U8 rtype, U8 rid, U8 *buf, U8 req)
     return (0);
 }
 
+// USB HID override function return 1 if the activity is trivial or response is null 
+__attribute__((weak))
+uint8_t usbd_hid_no_activity(U8 *buf)
+{
+    return 0;
+}
+
 // USB HID Callback: when data is received from the host
 void usbd_hid_set_report(U8 rtype, U8 rid, U8 *buf, int len, U8 req)
 {
+    main_led_state_t led_next_state = MAIN_LED_FLASH;
     switch (rtype) {
         case HID_REPORT_OUTPUT:
             if (len == 0) {
@@ -123,6 +131,10 @@ void usbd_hid_set_report(U8 rtype, U8 rid, U8 *buf, int len, U8 req)
                 free_count--;
                 memcpy(USB_Request[recv_idx], buf, len);
                 DAP_ExecuteCommand(buf, USB_Request[recv_idx]);
+                if(usbd_hid_no_activity(USB_Request[recv_idx]) == 1){
+                    //revert HID LED to default if the response is null
+                    led_next_state = MAIN_LED_DEF;
+                }
                 recv_idx = (recv_idx + 1) % DAP_PACKET_COUNT;
                 send_count++;
                 if (USB_ResponseIdle) {
@@ -132,8 +144,8 @@ void usbd_hid_set_report(U8 rtype, U8 rid, U8 *buf, int len, U8 req)
             } else {
                 util_assert(0);
             }
-
-            main_blink_hid_led(MAIN_LED_FLASH);
+            
+            main_blink_hid_led(led_next_state);
 
             break;