Blink leds while switches are pressed in Tiva C - c

Question

I'm trying to make the PF0 and PF4 leds blink while the switches are pressed. But it simply does not turn on any leds.
I was told I needed to use two ports, I don't see why, since this can be done with only one port — in this case the port D — but it was suggested that I use the port K as well (?).
The board is a Tiva C TM4c1294nctpd
#include <stdint.h>
#include <stdbool.h>
#include "inc/hw_memmap.h"
#include "driverlib/debug.h"
#include "driverlib/gpio.h"
#include "driverlib/sysctl.h"
#include <inc/tm4c1294ncpdt.h>
uint32_t SW1,SW2; //
int main(void) {
while(1){
SYSCTL_RCGCGPIO_R=0X1100; // Enable port D
GPIO_PORTD_DIR_R=0X03; //enable the GPIO pin PN0,
GPIO_PORTD_DEN_R=0X03;
GPIO_PORTK_AHB_DIR_R=0;
GPIO_PORTK_AHB_DEN_R=0X03;
GPIO_PORTK_AHB_PUR_R=0X01;
SW1 = GPIO_PORTD_DATA_R&0x10; // read PF4 into SW1
SW2 = GPIO_PORTD_DATA_R&0x01; // read PF0 into SW2
if (!SW1 && !SW2) { // both pressed
GPIO_PORTD_DATA_R = 0x04;
} else if (!SW1) { // SW1 pressed
GPIO_PORTD_DATA_R = 0x02;
} else if (!SW2) { // SW2 pressed
GPIO_PORTD_DATA_R = 0x08;
} else { // neither
GPIO_PORTD_DATA_R = 0x00;
}
}
}

Answer 1

You have only enabled D0 and D1, but appear to be using D0, D1, D2, D3 and D4.
You have set D0 and D1 as output, but appear to be be using D1, D2, D3 as outputs.
You have set D0 as an output, but attempt to read it as an input.
The configuration of PORTK is entirely irrelevant if you are not using it.
The RCGCGPIO enables the clock for PORTN and PORTJ which you are not using at all.
I am not familiar with the part and have only briefly read the data sheet, but the the PORTD clock, direction and digital enable configuration should be as follows if the input/output code is itself correct.
SYSCTL_RCGCGPIO_R = 0x0008; // Enable port D clock
GPIO_PORTD_DIR_R = 0x0E; // D4, D0 input, D1 to D3 output.
GPIO_PORTD_DEN_R = 0x1F; // Enable D0 to D4
These initialisation settings need be done once only - before the loop, not inside it.
int main(void)
{
SYSCTL_RCGCGPIO_R = 0x0008; // Enable port D
GPIO_PORTD_DIR_R = 0x0E; // D4, D0 input, D1 to D3 output.
GPIO_PORTD_DEN_R = 0x1F; // Enable D0 to D4
for(;;)
{
uint32_t SW1 = GPIO_PORTD_DATA_R & 0x10; // read PD4 into SW1
uint32_t SW2 = GPIO_PORTD_DATA_R & 0x01; // read PD0 into SW2
if (!SW1 && !SW2) // both pressed
{
GPIO_PORTD_DATA_R = 0x04;
}
else if (!SW1) // SW1 pressed
{
GPIO_PORTD_DATA_R = 0x02;
}
else if (!SW2) // SW2 pressed
{
GPIO_PORTD_DATA_R = 0x08;
}
else // neither
{
GPIO_PORTD_DATA_R = 0x00;
}
}
}
After thought:
The comments in the presumably copy & pasted code suggest the board might be an EK-TM4C1294XL. In that case the the LEDs are called D1, D2, D3, D4 (D for diode, not _PORTD), but are on GPIOs PN1, PN0, PF4 and PF0 respectively, and the switches are on PJ0 and PJ1.
In that case perhaps the following will be more successful:
int main(void)
{
SYSCTL_RCGCGPIO_R |= (1<<5 | 1<<8 | 1<<12); // Enable port F, J and N clocks
GPIO_PORTN_DIR_R |= 0x03; // PN1 = LED0, PN0 = LED1 (Outputs)
GPIO_PORTN_DEN_R |= 0x03; // Enable PN0 and PN1
GPIO_PORTF_DIR_R |= 0x11; // PF4 = LED3, PF0 = LED4 (Outputs)
GPIO_PORTF_DEN_R |= 0x11; // Enable PF0 and PF4
GPIO_PORTJ_DIR_R &= ~0x03; // PJ0 = SW1, PJ1 = SW2 (Inputs)
GPIO_PORTJ_DEN_R &= ~0x03; // Enable PJ0 and PJ4
for(;;)
{
uint32_t SW1 = GPIO_PORTJ_DATA_R & 0x01; // read PJ0 into SW1
uint32_t SW2 = GPIO_PORTJ_DATA_R & 0x02; // read PJ1 into SW2
if (!SW1 && !SW2) // both pressed
{
GPIO_PORTF_DATA_R = 0x01; // LED4
}
else if (!SW1) // SW1 pressed
{
GPIO_PORTF_DATA_R = 0x10; // LED3
}
else if (!SW2) // SW2 pressed
{
GPIO_PORTN_DATA_R = 0x01; // LED2
}
else // neither
{
GPIO_PORTN_DATA_R = 0x02; // LED1
}
}
}
This remains broken because the code only ever switches LED's on - an it does not respect other hardware that may be connected to other pins on ports F and N; you need to add code to read-modify-write the respective pins fo reach LED you set, you need to clear the other three. I'll leave that to you - it goes beyond the original question.