View source for TM4C123 GPIO Port Interrupt Tasks

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== Tasks ==
=== 1. Sample program (SW1 Interrupt) ===
* Create a CCS Project with "Empty Project"
* Download [{{SERVER}}/emsys/tivac/sw1_int.c <big>sw1_int.c</big>] program and <big>Add</big> this file to your project.
* Open tm4c123gh6pm_startup_ccs_gcc.c for editing and replace <u>''IntDefaultHandler''</u> with the ''GPIOPortF_Handler'' in the GPIO PortF vector position.
* Build and Debug (Run) the program.
*: Run this code and load it into the flash of microcontroller. You will see that the blue LED gets turned on when user switch is pressed first then if it is pressed again it gets turned off.

=== 2. GPIOF interrupt from SW1 and SW2 ===
* Rewrite [{{SERVER}}/emsys/tivac/sw1_int.c <big>sw1_int.c</big>] program to distinguish the interrupt pin. Toggle Red LED on PF1 continuously. Upon pressing either SW1 or SW2, the Green or Blue LED will toggle three times. main program toggles Red LED while waiting for interrupt from SW1 or SW2.

=== 3. Interrupt from External Source ===
* Write a program to toggle an LED at the same rate as the input frequency by connecting a square wave of 3.3V to a pin of Portx. (You can make it to toggle on positive or negative edge)
*:'''Hint''': Configure PORTD6 to trigger interrupt by falling edge. In the interrupt handler, the green LED (PF3) is toggled. The green LED should have half the frequency of the input signal at PORTD6. IRQ3 is assigned to PORTD6.
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=== 4. UART0 Interrupt Programming to receive data ===
[{{SERVER}}/emsys/tivac/tm4c_uart_echo.c] 
* UART0 Echo Program showed how UART0 receives data by polling the RXFE status flag. The disadvantage with that program is that it ties down the CPU polling the status flag. Modify it to make it an interrupt driven program.
*: '''Hint:''' Examining the UARTIM (UART Interrupt Mask) register, we see bit 4 allows us to enable the receive interrupt. If the receive interrupt for UART is enabled, when a byte is received, the receive flag is directed to NVIC and that causes the interrupt handler associated with the UART0 to be executed. In the UART0 handler we must read the received byte and clear the interrupt flag.

=== 5. Using SysTick with Interrupt ===
* Setup the SysTick to interrupt at '''1 Hz''' (Assume the system clock is running at 16 Mhz). Toggle the Red LED using the SysTick interrupt.
*:'''Hint''': The SysTick timer was discussed [[EmSys:TM4C123 Using SysTick with Interrupt | here]]. If '''INTEN'''=1 (INTEN is D1 of the STCTRL register), when the COUNT flag is set, it causes an interrupt via the NVIC.
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== See Also ==
# [[EmSys:Tiva C Series TM4C123GXL Board | EK-TM4C123GXL LaunchPad Board]]
# [[EmSys:Programming the GPIO in TM4C123 | GPIO Programming]]




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