Tiva Lab 03: Seven Segment Display

EK-TM4C123GXL LaunchPad

Pin configurations:

EK-TM4C1294XL LaunchPad

Pin configurations:

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <stdbool.h>

#include "TM4C123GH6PM.h"
#include "MyDefines.h"

void DelayMs(int ms);   // Software Delay Function
void SegDisplay(uint8_t d);
void Setup_GPIO(void);
// You nave to finish the following array for Seven Segment Display
char SevenSeg[] = { 0x3f,   // 0
                    0x06,   // 1
                            // You have to finish this array for 7-seg display
                  };

int main()
{
    char    ch = 0;
    int     i  = 0;
    // Place your initialization/startup code here (e.g. Setup_GPIO() )
    Setup_GPIO();

    while (1) {
        // Place your application code here
        for (i = 0; i < sizeof(SevenSeg); i++) {
            SegDisplay(ch & 0x0F);
            ch++;
            DelayMs(1000);
        }
    }
}
//------------------------------------------------------------------------------
void SegDisplay(uint8_t d)
{
    char    seg;

    seg = SevenSeg[?];

}
//------------------------------------------------------------------------------
void Setup_GPIO(void)
{
    // Configure GPIOs
    // 1. Enable Clock to the GPIO Modules (SYSCTL->RCGCGPIO |= (_PORTs);)
    SYSCTL->RCGCGPIO |= (__);
    // allow time for clock to stabilize (SYSCTL->PRGPIO & (_PORTs))
    while((SYSCTL->PRGPIO & (__)) != (__)) {};
    // 2. Unlock GPIO only PD7, PF0 on TM4C123G; PD7, PE7 on TM4C1294 (GPIOx->LOCK = 0x4C4F434B; and GPIOx->CR = _PINs;)
    GPIOD->LOCK = 0x4C4F434B;
    GPIOD->CR |= _PIN7;
    GPIOD->LOCK = 0;
    GPIOF->LOCK = 0x4C4F434B;
    GPIOF->CR |= _PIN0;
    GPIOF->LOCK = 0;
    // 3. Set Analog Mode Select bits for each Port (GPIOx->AMSEL = _PINs; 0=digital, 1=analog)
    // 4. Set Port Control Register for each Port (GPIOx->PCTL = PMCn << _PTCL_PINn, check the PCTL table)
    // 5. Set Alternate Function Select bits for each Port (GPIOx->AFSEL = _PINs; 0=regular I/O, 1=PCTL peripheral)
    // 6. Set Output pins for each Port (Direction of the Pins: GPIOx->DIR = _PINs; 0=input, 1=output)

    // 7. Set PUR bits (internal Pull-Up Resistor), PDR (Pull-Down Resistor), ODR (Open Drain) for each Port (0: disable, 1=enable)

    // 8. Set Digital ENable register on all port.pins (GPIOx->DEN = _PINs; 0=disable, 1=enable)

}
//------------------------------------------------------------------------------
// Delay ms milliseconds (16MHz CPU Clock)
void DelayMs(int ms)
{
    volatile int i, j;
    for (i = 0; i < ms; i++)
        for (j = 0; j < 4167; j++) {} // Do nothing for 1ms
}

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <stdbool.h>

#include "TM4C1294NCPDT.h"
#include "MyDefines.h"

void DelayMs(int ms);   // Software Delay Function
void SegDisplay(uint8_t d);
void Setup_GPIO(void);
// You nave to finish the following array for Seven Segment Display
char SevenSeg[] = { 0x3f,   // 0
                    0x06,   // 1
                            // You have to finish this array for 7-seg display
                  };

int main()
{
    char    ch = 0;
    int     i  = 0;
    // Place your initialization/startup code here (e.g. Setup_GPIO() )
    Setup_GPIO();

    while (1) {
        // Place your application code here
        for (i = 0; i < sizeof(sevenSeg); i++) {
            SegDisplay(ch & 0x0F);
            ch++;
            DelayMs(1000);
        }
    }
}
//------------------------------------------------------------------------------
void SegDisplay(uint8_t d)
{
    char    seg;

    seg = SevenSeg[?];

}
//------------------------------------------------------------------------------
void Setup_GPIO(void)
{
    // Configure GPIOs
    // 1. Enable Clock to the GPIO Modules (SYSCTL->RCGCGPIO |= (_PORTs);)
    SYSCTL->RCGCGPIO |= (__);
    // allow time for clock to stabilize (SYSCTL->PRGPIO & (_PORTs))
    while((SYSCTL->PRGPIO & (__)) != (__)){};
    // 2. Unlock GPIO only PD7, PF0 on TM4C123G; PD7, PE7 on TM4C1294 (GPIOx->LOCK = 0x4C4F434B; and GPIOx->CR = _PINs;)
    // 3. Set Analog Mode Select bits for each Port (GPIOx->AMSEL = _PINs; 0=digital, 1=analog)
    // 4. Set Port Control Register for each Port (GPIOx->PCTL = PMCn << _PTCL_PINn, check the PCTL table)
    // 5. Set Alternate Function Select bits for each Port (GPIOx->AFSEL = _PINs; 0=regular I/O, 1=PCTL peripheral)
    // 6. Set Output pins for each Port (Direction of the Pins: GPIOx->DIR = _PINs; 0=input, 1=output)

    // 7. Set PUR bits (internal Pull-Up Resistor), PDR (Pull-Down Resistor), ODR (Open Drain) for each Port (0: disable, 1=enable)

    // 8. Set Digital ENable register on all port.pins (GPIOx->DEN = _PINs; 0=disable, 1=enable)

}
//------------------------------------------------------------------------------
// Delay ms milliseconds (16MHz CPU Clock)
void DelayMs(int ms)
{
    volatile int i, j;
    for (i = 0; i < ms; i++)
        for (j = 0; j < 1605; j++) {} // Do nothing for 1ms
}

Write a C code to have your display count up from 0 to F (and then roll over to 0 again), with each digit displayed for one second.

1. Modify your code, and add the onboard SW1 function to your project.
2. After a power reset, the counter is STOP, and displays '0' on the 7-Segment Display.
3. When the user presses SW1, the counter START to count up from 0 to F with a 1-sec interval and rolls over to 0 again.
4. Users can press SW1 to PAUSE / CONTINUE the counter.

You can use software edge detection to implement the code:

The pseudocode for the Polling solution:

// Implement the following code inside the main() function

create bool variables: preSw1, curSw1, isPause
create integer variable: i, count
set preSw1 to true
set isPause to true
set i, count to zero

setup GPIO
display '0' on 7-seg display

loop
    // 1. Read Current State
    read current SW1 state to curSw1

    // 2. Detect the falling edge
    if (falling edge occurred)
        invert isPause value
    endif

    // 3. Update preSw1 from curSw1
    set preSw1 from curSw1

    if isPause not true
        increase count by 1
        if count greater than 50
            set count to zero
            increase i value by 1
            display i value on the 7-seg display
        endif
    endif
    delay for 10 ms

repeat

Questions

1. What type of seven-segment display did you use in this lab?
2. Complete Table 1, which shows which segments must be illuminated to display the hex digits 0..F.
3. If you used a common anode (CA) 7-segment display instead of a common cathode (CC) one, what change would you have to make in the wiring and the code?
4. In this lab, we use eight resistors for each LED on a 7-segment display unit. Instead of using eight resistors, can you just use one 220 ohm resistor connected to the common ground of the unit, and have the equivalent circuit? Explain why or why not.

Now, add on-board SW1 and SW2 to the project. SW1 is for RESET, and SW2 is for COUNT.

1. When the user presses the RESET (SW1) button, reset the counter value to zero and display "0".
2. When the user presses the COUNT (SW2) button, increase the counter value by 1 and display it on the seven-segment display.
3. The counter only increases at the moment when the COUNT (SW2) button is pressed (falling edge on signal input pin).

Hint:

The RESET key has a higher priority than the COUNT key, so you need to check the RESET key state first. If the user does not press the RESET key, then check the COUNT key.

Question

5. How do you detect the rising edge on the COUNT (SW2) button? Show your code and explain it.
6. Do we need to detect the signal edges on the RESET (SW1) button? And why?