Me and Johan read through and fixed tasks session2.

Session2/PWM/main.c

@@ -14,7 +14,7 @@
 
 
 /*
-    In this exercise, you will use PWM to control the brightness of LEDs
+    In this exercise, you will use PWM to control the brightness of LEDs.
     Once we have PWM set up, controling the brightness is super easy!
 */
 
@@ -22,8 +22,9 @@ int main(void)
 {
 	//Set up the leds and buttons. You might want to copy this from previous exercises.
 	
-	/*We will be using timer 1 in split (not single) mode. We use split to get access to WO4 and WO5, see Figure 19-13.
-	  It is highly recommended that you read chapter 19.3.3.4 and 19.3.3.6 in the datasheet. 
+	/*We will be using timer TCA0 in Split (not Single) mode. We use Split mode to output 
+          waveforms on WO4 and WO5, see Figure 19-13.
+	  It is highly recommended that you read chapter 19.3.3.4 and 19.3.3.6 in the megaAVR® 0-series. 
 	  There you will find a sub-chapter on the single-slope PWM we will be using.
 	*/
 	
@@ -33,21 +34,24 @@ int main(void)
 	
 	//We have to override the normal pin opperation so the PWM is pushed directly to the pin
 	//Hint: WO4 and WO5 are connected to leds. We need to override them to get the PWM out.
+	//See Datasheet to ATmega4809 for pins.
 	
-	
-	
+		
 	/*Timer A is a 16 bit timer.
-	When we use split mode, this will be split into two 8 bit timers. This will give us a frequency of 25Hz/2, we can see it flicker.
-	  By lowering the period, (PER) we get higher frequency at the cost of lower resolution. (Since in split mode, we must use HPER or LPER.)
+	When we use split mode, this will be split into two 8 bit timers. 
+	By lowering the period, (PER) we get higher frequency at the cost of lower resolution. 
+	(Since in split mode, we must use LPER(for WO0-WO2) and HPER (for WO3-WO5).
 	*/
 	
 	//Set the period to 0xff bit. (What frequency does this give?)
-	
+
 	
 	//We can now control the PWM duty cycle by simply writing values to the CMP0 and CMP1 registers.
 	TCA0.SPLIT.HCMP1 = 0x00; //Max brightness (Leds are inverted)
 	TCA0.SPLIT.HCMP2 = 0xff; //Min brightness (Leds are inverted)
 	
+	//Set Duty cycle of WO4 to 0x7f to see it twinkle.
+	
 	
     while(1){
 		

Session2/Timer/main.c

@@ -20,21 +20,21 @@ int main(void)
 	*/
 
 	
-	/*We will be using timer A that will trigger an overflow interupt.
+	/*We will be using timer A (TCA0) that will trigger an overflow interupt.
 	  This is a 16 bit timer that can run in 2 modes
-		-single mode as 1 16-bit timer
-		-dual/split mode as 2 8-bit timers
+		-single mode as one 16-bit timer
+		-dual/split mode as two 8-bit timers
 	  We will be using single mode in this exercise.
 	  
 	  Hint because the register names can be hard to understand:
 	  TCA0.SINGLE.CTRLA addresses the control A register for timer A
 	  
 	  First we set the prescaler to clk=clk/256 and enable the timer. 
-	  This is done by setting the right bits in the control A register.
+	  This is done by setting the correct bits in the control A register.
 	*/
 
 	
-	//Next we Enable timer interupt for overflow on timer A. 
+	//Next we Enable timer interupt for overflow on TCA0. 
 
 	
 	//Finally we have to set the max value of the timer, the top. 
@@ -44,7 +44,7 @@ int main(void)
 	
 	
 	//To be able to react to the interrupts from the module we have to enable interrupts globally.
-	//This is done in the function sei(), whih is located in the already included header file <avr/interrupt.h>
+	//This is done in the function sei(), which is located in the already included header file <avr/interrupt.h>
 	sei();
 	
     while(1){
@@ -61,4 +61,4 @@ ISR(TCA0_OVF_vect){
 	//Clear the interrupt flag.
 	//If we do not clear the flag, we will instantly jump back into the ISR again
 	
-}
\ No newline at end of file
+}

Session2/UART/main.c

@@ -8,16 +8,17 @@
 #include <util/delay.h>
 
 /*
-In this exercise we will set up and use UART communication.
+In this exercise we will set up and use USART communication.
 The embedded debugger has a virtual com port that we will use to communicate with the computer.
 
 */
 
 
-void uart_init(unsigned long baud){
+void usart_init(unsigned long baud){
 	
-	//In this function, we want to initialize the UART.
-	//Chapter 24.3 in datasheet tells us how this is done:
+	//In this function, we want to initialize the USART.
+	//Chapter 22.3 in datasheet tells us how this is done:
+	//You can see on the datasheet for Curiosity Nano that USART3 connects to the usb.
 	
 	//Set TX pin as output
  	//Set the TX pin high
@@ -29,38 +30,38 @@ void uart_init(unsigned long baud){
 }
 
 // function to transmit data
-void uart_transmit(unsigned char data){
-	//In this function we will be send data.
+void usart_transmit(unsigned char data){
+	//In this function we will send data.
 	
 	//First we should check that there isn't already data being sent
 	//	-if there is, we should probably wait for it to finish first
 	
-	//Put our new data into se sending register
+	//Put our new data into the DATA register
 
 }
 
 
 int main(void)
 {
-	//Initialize the UART with our function. 
+	//Initialize the USART with our function. 
 	//We will be using a baudrate of 9600 (defined as BAUD_9600 at the top of the file)
 	
-	sei(); //Enable global interrupt, important for anything here to work
+	sei(); //Enable global interrupt, this is important for anything here to work
 	
     while (1) 
     {
 		//We don't really need to do anything here.
+		//If you want, you can continously send something over usart. It will be a good idea to include a small delay.
 		//the ISR will handle receiving. 
     }
 }
 
 
 //Interrupt service routine for the receiver.
-ISR(USART0_RXC_vect){
+ISR(USART3_RXC_vect){
 	
 	//Read out the received data to a variable
 	
-	//Do things with data. Perhaps send something back? 
-	
+	//Do things with data. Perhaps send something back? Maybe not the same as recieved?
 
-}
\ No newline at end of file
+}