TimerLib

Overview

The Timer class provides a lightweight and precise timing abstraction over the TM4C1294XL’s hardware GPTM (General-Purpose Timer Module). It supports both 32-bit and 64-bit (Wide Timer) modes, allowing you to measure elapsed time in microseconds or milliseconds without relying on SysTick, which makes it ideal for FreeRTOS or interrupt-based applications.

Hardware timer abstraction Supports 32-bit and 64-bit

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Features

• Uses TivaWare driverlib functions for reliability and precision.
• Works with TIMERx_BASE (32-bit) or WTIMERx_BASE (64-bit) peripherals.
• Provides micros() and millis() methods for elapsed time measurement.
• Independent from SysTick and non-blocking.
• Automatically enables and configures timer peripherals.
• Compatible with low-level hardware timing and performance profiling.

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Basic Usage

#include "timerLib.h"

Timer t;

int main(void)
{
    uint32_t gSystemClock = SysCtlClockFreqSet(
        SYSCTL_XTAL_25MHZ | SYSCTL_OSC_MAIN |
        SYSCTL_USE_PLL | SYSCTL_CFG_VCO_480, 120000000);

    t.begin(gSystemClock, WTIMER0_BASE);

    while (1) {
        uint64_t ms = t.millis();
        // Use ms for periodic tasks or delay control
    }
}

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API Summary

Constructor

Timer();

Creates an uninitialized timer instance.

Initialization

bool begin(uint32_t sysclkHz, uint32_t timerBase);

Initializes and enables the selected timer peripheral.

• sysclkHz: System clock frequency in Hz (e.g., 120000000).
• timerBase: Base address of the timer (e.g., TIMER0_BASE, WTIMER0_BASE).
• Returns true on success.

Control Methods

Method	Description
void stop()	Stops the timer without resetting configuration.
void reset()	Resets the logical start time reference.

Time Access

Method	Description
uint64_t micros() const	Returns elapsed time in microseconds.
uint64_t millis() const	Returns elapsed time in milliseconds.

Query Methods

Method	Description
uint32_t base() const	Returns the base address used by the timer.
bool isWide() const	Returns true if using a 64-bit wide timer.

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Example: LED Blink with millis()

#include "timerLib.h"
#include "driverlib/gpio.h"

#define LED_PORT GPIO_PORTN_BASE
#define LED_PIN  GPIO_PIN_1

Timer t;

int main(void)
{
    uint32_t sysclk = SysCtlClockFreqSet(
        SYSCTL_XTAL_25MHZ | SYSCTL_OSC_MAIN |
        SYSCTL_USE_PLL | SYSCTL_CFG_VCO_480, 120000000);

    SysCtlPeripheralEnable(SYSCTL_PERIPH_GPION);
    while(!SysCtlPeripheralReady(SYSCTL_PERIPH_GPION));
    GPIOPinTypeGPIOOutput(LED_PORT, LED_PIN);

    t.begin(sysclk, TIMER0_BASE);

    uint64_t last = t.millis();
    bool led = false;

    while (1) {
        uint64_t now = t.millis();
        if (now - last >= 500) {
            led = !led;
            GPIOPinWrite(LED_PORT, LED_PIN, led ? LED_PIN : 0);
            last = now;
        }
    }
}

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Integration Notes

• Always call begin() after system clock setup.
• Works with any GPTM module (Timer0–Timer5, WideTimer0–WideTimer5).
• Does not configure interrupts; meant for software polling.
• Ideal for measuring time intervals, creating periodic events, or benchmarking.

Dependencies

• driverlib/sysctl.h
• driverlib/timer.h
• inc/hw_memmap.h

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License and Credits

Developed for ECE3849 — Real-Time Embedded Systems. Based on TI TivaWare GPTM drivers and adapted for object-oriented use in C++.

Author: Edwin R. Version 1.0