Stopwatch on Xilinx NEXYS A7 Board using Vitis ISE(C-Code)

Max (luit) OP 2023-01-19 14:27 #7321322

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Can anyone help me to build Stopwatch with Start/stop, reset, pause/resume functionalities?

I have .xsa bitstream from Vivado and want to implement it on 7-segment display of Xilinx NEXYS A7 board using C-Code (Xilinx Vitis ISE).

I'm not good with C and have to consider C in this case. The following is the code but not really working.

#include "xparameters.h" #include "xgpio.h" #include "xtmrctr.h" #include <unistd.h> #include "xstatus.h"

#define LED_AN_ADDR 0x40000000 //base address for digit select signals #define LED_DIS_ADDR 0x40010000 //base address for 7-segment displays #define SW_ADDR 0x40020000 //base address for 16 switches #define TMRCTR_DEVICE_ID XPAR_TMRCTR_0_DEVICE_ID //device ID for the on-board timer

#define TIMER_FREQ 100000000 // Timer frequency in Hz #define DISPLAY_PERIOD 100000000/10 // Period for updating the display in clock cycles

XGpio Gpio_LedAn; XGpio Gpio_LedDis; XGpio Gpio_Sw; XTmrCtr Timer;

unsigned int hours = 0; // Time in hours unsigned int minutes = 0; // Time in minutes unsigned int seconds = 0; // Time in seconds int state = 0; // 0 = stopped, 1 = running void delay(unsigned int delay_count) { unsigned int i; for (i = 0; i < delay_count; i++); }

unsigned int get7segData(int num) { static const unsigned int segData[] = {0x3F, 0x06, 0x5B, 0x4F, 0x66, 0x6D, 0x7D, 0x07, 0x7F, 0x6F}; if(num >= 0 && num <= 999999) { unsigned int result = 0; int i; for (i = 0; i < 6; i++) { result |= segData[num % 10] << (i * 8); num /= 10; } return result; } else { return 0; } }

void update_display() { // turn off all digit select signals XGpio_DiscreteWrite(&Gpio_LedAn, 1, 0x00000000);

// Display hour tens digit on the leftmost 7-segment display

XGpio_DiscreteWrite(&Gpio_LedDis, 1, get7segData(hours / 10));

XGpio_DiscreteWrite(&Gpio_LedAn, 1, 0x1); // turn on digit select signal for leftmost display

delay(0.05 * 1000000);

// Display hour ones digit on the second leftmost 7-segment display

XGpio_DiscreteWrite(&Gpio_LedDis, 1, get7segData(hours % 10));

XGpio_DiscreteWrite(&Gpio_LedAn, 1, 0x2); // turn on digit select signal for second leftmost display

delay(0.05 * 1000000);

// Display minute tens digit on the third leftmost 7-segment display

XGpio_DiscreteWrite(&Gpio_LedDis, 1, get7segData(minutes / 10));

XGpio_DiscreteWrite(&Gpio_LedAn, 1, 0x4); // turn on digit select signal for third leftmost display

delay(0.05 * 1000000);

// Display minute ones digit on the fourth leftmost 7-segment display

XGpio_DiscreteWrite(&Gpio_LedDis, 1, get7segData(minutes % 10));

XGpio_DiscreteWrite(&Gpio_LedAn, 1, 0x8); // turn on digit select signal for fourth leftmost display

delay(0.05 * 1000000);

// Display second tens digit on the fifth leftmost 7-segment display

XGpio_DiscreteWrite(&Gpio_LedDis, 1, get7segData(seconds / 10));

XGpio_DiscreteWrite(&Gpio_LedAn, 1, 0x10); // turn on digit select signal for fifth leftmost display

delay(0.05 * 1000000);

// Display second ones digit on the rightmost 7-segment display

XGpio_DiscreteWrite(&Gpio_LedDis, 1, get7segData(seconds % 10));

XGpio_DiscreteWrite(&Gpio_LedAn, 1, 0x20); // turn on digit select signal for rightmost display

delay(0.05 * 1000000);

// turn off all digit select signals

XGpio_DiscreteWrite(&Gpio_LedAn, 1, 0x00000000);

}

void timer_interrupt(void *CallbackRef, u8 TmrCtrNumber) { // call the function to display the time on the 7-segment displays update_display(); // increment the time seconds++; if (seconds == 60) { seconds = 0; minutes++; } if (minutes == 60) { minutes = 0; hours++; } if (hours == 100) { hours = 0; } // reset the timer counter value XTmrCtr_Reset(CallbackRef, TmrCtrNumber); // call the function to display the time on the 7-segment displays //Read switches int switches = XGpio_DiscreteRead(&Gpio_Sw, 1);

// Check the reset switch

if (switches & 0x1) {

    // Reset the timer

    hours = 0;

    minutes = 0;

    seconds = 0;

// Check the start/stop switch

if (switches & 0x2) {

    // Toggle the state of the stopwatch

    state = !state;

// If the stopwatch is running, re-enable the timer interrupt

if (state) {

XTmrCtr_EnableIntr(&Timer, TmrCtrNumber);

}

int main() { int status;

// Initialize the digital I/O for the 7-segment displays and digit select signals

status = XGpio_Initialize(&Gpio_LedDis, LED_DIS_ADDR);

if (status != XST_SUCCESS) return XST_FAILURE;

status = XGpio_Initialize(&Gpio_LedAn, LED_AN_ADDR);

if (status != XST_SUCCESS) return XST_FAILURE;

// Initialize the digital I/O for the 16-bit switches

status = XGpio_Initialize(&Gpio_Sw, SW_ADDR);

if (status != XST_SUCCESS) return XST_FAILURE;

// Initialize the timer

status = XTmrCtr_Initialize(&Timer, TMRCTR_DEVICE_ID);

if (status != XST_SUCCESS) return XST_FAILURE;

// Set the timer to generate an interrupt every 1 second

XTmrCtr_SetResetValue(&Timer, 0, DISPLAY_PERIOD);

XTmrCtr_SetOptions(&Timer, 0, XTC_INT_MODE_OPTION | XTC_AUTO_RELOAD_OPTION);

// Register the timer interrupt handler

XTmrCtr_SetHandler(&Timer, timer_interrupt, &Timer);

// Enable the global interrupt

microblaze_enable_interrupts();

// Start the timer

XTmrCtr_Start(&Timer, 0);

return 0;

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Andreas M. (amesser) 2023-01-19 14:36 #7321332

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Where is the point in using an FPGA board to implement a function using "C" language? What CPU is the "C" code going to be compiled for and run on? Wouldn't it be simpler to just implement the Stopwatch in hdl and use the FPGA as is?

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Max (luit) OP 2023-01-19 14:48 #7321343

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OS : Standalone Processor: Microblaze

I agree with you, it is simpler in hdl but the challenge is to use C and it is not working as expected cause I couldnot find and fix issues.

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Andreas M. (amesser) 2023-01-19 21:15 #7321880

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Its not good style to edit a post afterwards and add big amounts of extra information not provided in the first place. It makes other people look like fools. You should have typed that into your new post. Regarding your program:

Checking every second the input pin state will not work. One has to hold Keys for at least one second to have the keypress recognized. Furthermore if key is pressed a bit longer than one second it might "detect" two key presses. You need proper edge detection. (and maybe as well debouncing)

At the end of main() you just return. That exits your application. If you do that, your application is gone. Most likely the platform specific c runtime code will also do a reset of your software in that case. In most cases, embedded applications are not supposed to return from main() at all.

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