CCS/TMS320F28379D: How to interface alphanumeric keypad?

Adarsh Kumar1

Part Number: TMS320F28379D
Other Parts Discussed in Thread: C2000WARE

Tool/software: Code Composer Studio

I tried interfacing 4x4 alphanumeric keypad with F28379D microcontroller kit but it was of no use. I know out of eight pins 4 correspond to row and 4 other correspond to columns. I think that on pressing a key, two pins get short circuited. How can I proceed further? Please help

over 4 years ago

0 Keith Barkley over 4 years ago

Guru 39760 points

I think we need more details, but if what you are saying is correct, you need to dedicate 4 digital outputs and 4 digital inputs.

And the logic goes like this:

keypressed = false;

Foreach output pin 0 - 3: OP

Foreach input pin 0 - 3: IP

If IP is high

{ return OP and IP ; keypressed = true; break }

next IP

Next OP

if keypressed == true

// figure out what key was pressed based on OP and IP

else

// no key pressed

endif

0 Devin Cottier over 4 years ago in reply to Keith Barkley

TI__Guru 60865 points

Hi Adarsh,

As Keith stated, we'll need additional information to determine the issue. I think you'll want to summarize:

Diagram of how the keypad functions / makes connections
Your strategy of how you intend to interface with the keypad and how you expect to detect the key presses
The results you actually got vs. your expectation

0 Adarsh Kumar1 over 4 years ago in reply to Keith Barkley

Prodigy 70 points

This is the keypad I am using

0 Adarsh Kumar1 over 4 years ago in reply to Devin Cottier

Prodigy 70 points

I have added the image of keypad in a separate reply.

I think logic given by Keith would solve the issue. However, I have just started using the microcontroller kit and want to know how to dedicate a particular pin as input or a output pin

Thanks in advance.

0 Devin Cottier over 4 years ago in reply to Adarsh Kumar1

TI__Guru 60865 points

Hi Adarsh,

Have a read through the GPIO example code in c2000ware here:

\driverlib\f2837xd\examples\cpu1\gpio

In particular, some examples of making a pin a GPIO as input or output:

    //
    // Make GPIO34 an input on GPIO34
    //
    GPIO_setPadConfig(34, GPIO_PIN_TYPE_PULLUP);     // Enable pullup on GPIO34
    GPIO_setPinConfig(GPIO_34_GPIO34);               // GPIO34 = GPIO34
    GPIO_setDirectionMode(34, GPIO_DIR_MODE_IN);     // GPIO34 = input

And

    //
    // Enable an GPIO output on GPIO6
    //
    GPIO_setPadConfig(6, GPIO_PIN_TYPE_PULLUP);   // Enable pullup on GPIO6
    GPIO_writePin(6, 1);                          // Load output latch
    GPIO_setPinConfig(GPIO_6_GPIO6);              // GPIO6 = GPIO6
    GPIO_setDirectionMode(6, GPIO_DIR_MODE_OUT);  // GPIO6 = output

Note that the output state for an output is controlled by

GPIO_writePin(6, 1);                          // Load output latch

You'll also probably want to take a look at the driverlib GPIO module documentation in c2000ware in:

/device_support/f2837xd/docs/html/driverlib_html/group__gpio__api.html

And the "General-Purpose Input/Output (GPIO)" chapter in the TRM (http://www.ti.com/lit/ug/spruhm8i/spruhm8i.pdf)

0 Adarsh Kumar1 over 4 years ago in reply to Keith Barkley

Prodigy 70 points

This is the code I wrote after importing gpio_setup from C2000ware and based on keith's logic:

// Included Files
//
#include "driverlib.h"
#include "device.h"
#include <stdio.h>

#define EXAMPLE1 1  // Basic pinout configuration example
#define EXAMPLE2 0  // Communication pinout example

//
// Function Prototypes
//
void setup1GPIO(void);

//
// Main
//
void main(void)
{
    //
    // Initializes system control, device clock, and peripherals
    //
    Device_init();

    //
    // Initializes PIE and clear PIE registers. Disables CPU interrupts.
    // and clear all CPU interrupt flags.
    //
    Interrupt_initModule();

    //
    // Initialize the PIE vector table with pointers to the shell interrupt
    // Service Routines (ISR).
    //
    Interrupt_initVectorTable();

#if EXAMPLE1

    //
    // This example is a basic pinout
    //
    setup1GPIO();

#endif  // - EXAMPLE1


}

void setup1GPIO(void){
    GPIO_setPadConfig(6, GPIO_PIN_TYPE_PULLUP);     // Enable pullup on GPIO6
    GPIO_writePin(6, 1);
    GPIO_setPinConfig(GPIO_6_GPIO6);                // GPIO6 = GPIO6
    GPIO_setDirectionMode(6, GPIO_DIR_MODE_OUT);    // GPIO6 = output

    GPIO_setPadConfig(7, GPIO_PIN_TYPE_PULLUP);     // Enable pullup on GPIO7
    GPIO_writePin(7, 1);
    GPIO_setPinConfig(GPIO_7_GPIO7);                // GPIO7 = GPIO7
    GPIO_setDirectionMode(7, GPIO_DIR_MODE_OUT);    // GPIO7 = output

    GPIO_setPadConfig(8, GPIO_PIN_TYPE_PULLUP);     // Enable pullup on GPIO8
    GPIO_writePin(8, 1);
    GPIO_setPinConfig(GPIO_8_GPIO8);                // GPIO8 = GPIO8
    GPIO_setDirectionMode(8, GPIO_DIR_MODE_OUT);    // GPIO8 = output

    GPIO_setPadConfig(9, GPIO_PIN_TYPE_PULLUP);     // Enable pullup on GPIO9
    GPIO_writePin(9, 1);
    GPIO_setPinConfig(GPIO_9_GPIO9);                // GPIO9 = GPIO9
    GPIO_setDirectionMode(9, GPIO_DIR_MODE_OUT);    // GPIO9 = output

    //Input Pins

    GPIO_setPadConfig(10, GPIO_PIN_TYPE_PULLUP);     // Enable pullup on GPIO10
    GPIO_setPinConfig(GPIO_10_GPIO10);               // GPIO10 = GPIO10
    GPIO_setDirectionMode(10, GPIO_DIR_MODE_IN);     // GPIO10 = input

    GPIO_setPadConfig(11, GPIO_PIN_TYPE_PULLUP);     // Enable pullup on GPIO11
    GPIO_setPinConfig(GPIO_11_GPIO11);               // GPIO11 = GPIO11
    GPIO_setDirectionMode(11, GPIO_DIR_MODE_IN);     // GPIO11 = input

    GPIO_setPadConfig(14, GPIO_PIN_TYPE_PULLUP);     // Enable pullup on GPIO14
    GPIO_setPinConfig(GPIO_14_GPIO14);               // GPIO14 = GPIO14
    GPIO_setDirectionMode(14, GPIO_DIR_MODE_IN);     // GPIO14 = input

    GPIO_setPadConfig(15, GPIO_PIN_TYPE_PULLUP);     // Enable pullup on GPIO15
    GPIO_setPinConfig(GPIO_15_GPIO15);               // GPIO15 = GPIO15
    GPIO_setDirectionMode(15, GPIO_DIR_MODE_IN);     // GPIO15 = input

    int op = 0, ip = 0;
    int input_pin[4] = {10, 11, 14, 15};
    int output_pin[4] = {6, 7, 8, 9};

    int keypad[4][4] = { {1, 2, 3, 10},
                       {4, 5, 6, 11},
                       {7, 8, 9, 12},
                       {13, 14, 15, 16} };

    while(true){
        bool flag = 0;
        for(op = 0; op <= 3 && !flag; op++){
            GPIO_writePin(output_pin[op], 0);
            for(ip = 0; ip <= 3 && !flag; ip++){
                bool res = GPIO_readPin(input_pin[ip]);
                if(!res) flag = 1;
            }
        }
        if(flag)
            break;
    }
    int key_pressed = keypad[op][ip];
}

However, whatever key I press, 'res' remains 1. Any suggestions?

0 Devin Cottier over 4 years ago in reply to Adarsh Kumar1

TI__Guru 60865 points

Hi Adarsh,

I think if you directly connect one or more of the outputs to one or more of the inputs you can take the keypad out of the debug and just focus on the SW / GPIO setup portion of the debug?

Alternately or in addition, you might try using a DMM or scope to confirm that the pin logic levels are as expected when the keys are pressed or not?

0 Keith Barkley over 4 years ago in reply to Adarsh Kumar1

Guru 39760 points

GPIO_writePin(output_pin[op], 0);

I think this should be '1', not 0.

In any case you need to make sure that only one output is on at a time, i.e., you need to make sure all the outputs are 0 to start and that you turn off the previous one before you turn on the current one.

Also, since you do not have any breaks, op and ip will simply contain the last value from the for loop.

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CCS/TMS320F28379D: How to interface alphanumeric keypad?