From 71074a90363b3674ee2b20102d6cb217124bbe3e Mon Sep 17 00:00:00 2001
From: Libor Tomsik <libor@tomsik.eu>
Date: Fri, 17 Feb 2017 20:47:05 +0100
Subject: [PATCH 1/2] Implemented DTR pin feature.

---
 .../libraries/DigisparkCDC/DigiCDC.cpp          | 17 ++++++++++-------
 digistump-avr/libraries/DigisparkCDC/DigiCDC.h  |  1 +
 2 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/digistump-avr/libraries/DigisparkCDC/DigiCDC.cpp b/digistump-avr/libraries/DigisparkCDC/DigiCDC.cpp
index 938283a..c72fc30 100644
--- a/digistump-avr/libraries/DigisparkCDC/DigiCDC.cpp
+++ b/digistump-avr/libraries/DigisparkCDC/DigiCDC.cpp
@@ -16,6 +16,7 @@ and Digistump LLC (digistump.com)
 
 uchar              sendEmptyFrame;
 static uchar       intr3Status;    /* used to control interrupt endpoint transmissions */
+static uchar       portB_dtr_bit;
 
 DigiCDCDevice::DigiCDCDevice(void){}
 
@@ -143,8 +144,8 @@ void DigiCDCDevice::usbBegin()
     RingBuffer_InitBuffer(&rxBuf,rxBuf_Data,sizeof(rxBuf_Data));
 
     intr3Status = 0;
-    sendEmptyFrame = 0;    
-
+    sendEmptyFrame = 0;
+    portB_dtr_bit = 255;
     sei();   
 }
 
@@ -186,11 +187,11 @@ void DigiCDCDevice::usbPollWrapper()
     
 }
 
-
-
-
-
-
+void DigiCDCDevice::setDtrPin(uint8_t dtrPin){
+    portB_dtr_bit = dtrPin;
+    PORTB &= ~(_BV(portB_dtr_bit));
+    DDRB |= (1 << portB_dtr_bit);
+}
 
 #ifdef __cplusplus
 extern "C"{
@@ -320,6 +321,8 @@ usbRequest_t    *rq = (usbRequest_t*)((void *)data);
         /*    SET_LINE_CODING -> usbFunctionWrite()    */
         }
         if(rq->bRequest == SET_CONTROL_LINE_STATE){
+            if(portB_dtr_bit != 0xFF)
+                PORTB  = (PORTB&~(1<<portB_dtr_bit))|((rq->wValue.word&1)<<portB_dtr_bit);
             /* Report serial state (carrier detect). On several Unix platforms,
              * tty devices can only be opened when carrier detect is set.
              */
diff --git a/digistump-avr/libraries/DigisparkCDC/DigiCDC.h b/digistump-avr/libraries/DigisparkCDC/DigiCDC.h
index 31de73f..76a1cbb 100644
--- a/digistump-avr/libraries/DigisparkCDC/DigiCDC.h
+++ b/digistump-avr/libraries/DigisparkCDC/DigiCDC.h
@@ -42,6 +42,7 @@ class DigiCDCDevice  : public Stream {
         void refresh();
         void task();
         void delay(long milli);
+        void setDtrPin(uint8_t dtrPin);
         virtual int available(void);
         virtual int peek(void);
         virtual int read(void);

From 3921dc24ad7250f174055345fadc42890ec93072 Mon Sep 17 00:00:00 2001
From: Libor Tomsik <libor@tomsik.eu>
Date: Fri, 17 Feb 2017 20:54:18 +0100
Subject: [PATCH 2/2] Added example for DTR

---
 .../examples/CDC_DTR_LED/DigisparkDTR.ino             | 11 +++++++++++
 1 file changed, 11 insertions(+)
 create mode 100644 digistump-avr/libraries/DigisparkCDC/examples/CDC_DTR_LED/DigisparkDTR.ino

diff --git a/digistump-avr/libraries/DigisparkCDC/examples/CDC_DTR_LED/DigisparkDTR.ino b/digistump-avr/libraries/DigisparkCDC/examples/CDC_DTR_LED/DigisparkDTR.ino
new file mode 100644
index 0000000..8984c5d
--- /dev/null
+++ b/digistump-avr/libraries/DigisparkCDC/examples/CDC_DTR_LED/DigisparkDTR.ino
@@ -0,0 +1,11 @@
+#include <DigiCDC.h>
+void setup() {                
+  SerialUSB.begin();
+  // initialize the digital pin 1 as an DTR output.
+  SerialUSB.setDtrPin(1);
+}
+
+// the loop routine runs over and over again forever:
+void loop() {
+   SerialUSB.delay(10);
+}