add USB CDC RX & TX LEDs with 10ms minimum on time, tested

Author: ladyada

cores/arduino/USB/CDC.cpp

@@ -23,6 +23,8 @@
 #include <stdio.h>
 #include <stdint.h>
 
+uint8_t USB_TXLEDticks = 0, USB_RXLEDticks = 0;
+
 #ifdef CDC_ENABLED
 
 #define CDC_SERIAL_BUFFER_SIZE	256
@@ -98,6 +100,12 @@ bool CDC_Setup(USBSetup& setup)
 	uint8_t requestType = setup.bmRequestType;
 	uint8_t r = setup.bRequest;
 
+	digitalWrite(PIN_LED_RXL, HIGH);
+	digitalWrite(PIN_LED_TXL, HIGH);
+	pinMode(PIN_LED_RXL, OUTPUT);
+	pinMode(PIN_LED_TXL, OUTPUT);
+	USB_TXLEDticks = USB_RXLEDticks = 0;
+
 	if (requestType == REQUEST_DEVICETOHOST_CLASS_INTERFACE)
 	{
 		if (r == CDC_GET_LINE_CODING)
@@ -209,6 +217,9 @@ int Serial_::read(void)
 {
 	ring_buffer *buffer = &cdc_rx_buffer;
 
+	digitalWrite(PIN_LED_RXL, LOW);
+	USB_RXLEDticks = 10; // how many ms to keep LED on 
+
 	// if the head isn't ahead of the tail, we don't have any characters
 	if (buffer->head == buffer->tail && !buffer->full)
 	{
@@ -243,6 +254,9 @@ size_t Serial_::write(const uint8_t *buffer, size_t size)
 	 bytes sent before the user opens the connection or after
 	 the connection is closed are lost - just like with a UART. */
 
+        digitalWrite(PIN_LED_TXL, LOW);
+	USB_TXLEDticks = 10; // how many ms to keep LED on 
+
 	// TODO - ZE - check behavior on different OSes and test what happens if an
 	// open connection isn't broken cleanly (cable is yanked out, host dies
 	// or locks up, or host virtual serial port hangs)

cores/arduino/delay.c

@@ -19,6 +19,9 @@
 #include "delay.h"
 #include "Arduino.h"
 
+extern uint8_t USB_TXLEDticks, USB_RXLEDticks;
+
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -83,6 +86,21 @@ void SysTick_DefaultHandler(void)
   // Increment tick count each ms
   _ulTickCount++;
   tickReset();
+
+  // turn off CDC LEDs if time
+  if (USB_RXLEDticks) {
+    USB_RXLEDticks--;
+    if (USB_RXLEDticks == 0) {
+      digitalWrite(PIN_LED_RXL, HIGH);
+    }
+  }
+
+  if (USB_TXLEDticks) {
+    USB_TXLEDticks--;
+    if (USB_TXLEDticks == 0) {
+      digitalWrite(PIN_LED_TXL, HIGH);
+    }
+  }
 }
 
 #ifdef __cplusplus