libraries/SoftwareSerial/src/SoftwareSerial.cpp

@@ -202,6 +202,14 @@ void SoftwareSerial::setRX(uint8_t rx)
     pinMode(rx, INPUT_PULLUP);  // pullup for normal logic
   else
     pinMode(rx, INPUT);
+
+  // Save gpio_line for turning on/off interrupts
+  _int_maskLine = digitalPinToGpioIntLine(_receivePin);
+  // Init interrupt line
+  HAL_GPIO_InitInterruptLine((HAL_GPIO_Line_Config)digitalPinToGpioIntMux(_receivePin), 
+                            _inverse_logic ? GPIO_INT_MODE_RISING : GPIO_INT_MODE_FALLING);
+  GPIO_IRQ_LINE_DISABLE(_int_maskLine);           // turn off int line (it turning on while line init)
+  HAL_EPIC_MaskEdgeSet(HAL_EPIC_GPIO_IRQ_MASK);   // turn on the mask in EPIC
 }
 
 uint32_t SoftwareSerial::subtract_cap(uint32_t num, uint16_t sub) 
@@ -216,11 +224,8 @@ uint32_t SoftwareSerial::subtract_cap(uint32_t num, uint16_t sub)
 // Public methods
 //
 void SoftwareSerial::begin(long speed)
-{
-  // set pins config
-  setRX(_receivePin);
-  setTX(_transmitPin);
-  
+{ 
+  // delays are empirical values here
   _rx_delay_centering = _rx_delay_intrabit = _rx_delay_stopbit = _tx_delay = 0;
 
   // limit speed
@@ -230,14 +235,15 @@ void SoftwareSerial::begin(long speed)
   // Precalculate the various delays in number of ticks
   uint32_t bit_delay = F_CPU / speed;
   
-  // delays are empirical values here
-
-  // 1 bit delay while transmitting data
-  _tx_delay = subtract_cap(bit_delay, 35);
+  setTX(_transmitPin);
+  _tx_delay = subtract_cap(bit_delay, 35); // 1 bit delay while transmitting data
 
   // Only setup rx when we have a valid INT for this pin
   if (digitalPinToInterrupt(_receivePin) != NOT_AN_INTERRUPT) 
   {
+    // set pin config
+    setRX(_receivePin);
+  
     // We want to have a total delay of 1.5 bit time from start bit. Inside the loop, we already  
     // wait for 1 bit time, so here we wait for 0.5 bit time
     _rx_delay_centering = subtract_cap(bit_delay / 2, 315); 
@@ -248,14 +254,6 @@ void SoftwareSerial::begin(long speed)
     // This delay aims at 3/4 of a bit time, meaning the end of the delay will be at 1/4th of the stopbit. 
     // This allows some extra time for ISR cleanup, which makes 115200 baud at 16Mhz work more reliably   
     _rx_delay_stopbit = subtract_cap(bit_delay * 3 / 4, 142);
-
-    // Save gpio_line for turning on/off interrupts
-    _int_maskLine = digitalPinToGpioIntLine(_receivePin);
-    // Init interrupt line
-    HAL_GPIO_InitInterruptLine((HAL_GPIO_Line_Config)digitalPinToGpioIntMux(_receivePin), 
-                               _inverse_logic ? GPIO_INT_MODE_RISING : GPIO_INT_MODE_FALLING);
-    GPIO_IRQ_LINE_DISABLE(_int_maskLine);           // turn off int line (it turning on while line init)
-    HAL_EPIC_MaskEdgeSet(HAL_EPIC_GPIO_IRQ_MASK);   // turn on the mask in EPIC
   }
   else
     ErrorMsgHandler("SoftwareSerial.begin(): Rx pin does not support interrupts, use different pin");