CPU Timer Module

The CPU timer API provides a set of functions for configuring and using the CPU Timer module. Functions are provided to setup and configure the timer module operating conditions along with functions to get the status of the module and to clear overflow flag.

group cputimer_api

Enums

enum CPUTimer_EmulationMode

Values that can be passed to CPUTimer_setEmulationMode() as the mode parameter.

Values:

enumerator CPUTIMER_EMULATIONMODE_STOPAFTERNEXTDECREMENT = 0x0000

Denotes that the timer will stop after the next decrement.

enumerator CPUTIMER_EMULATIONMODE_STOPATZERO = 0x0400

Denotes that the timer will stop when it reaches zero.

enumerator CPUTIMER_EMULATIONMODE_RUNFREE = 0x0800

Denotes that the timer will run free.

enum CPUTimer_ClockSource

The following are values that can be passed to CPUTimer_selectClockSource() as the source parameter.

Values:

enumerator CPUTIMER_CLOCK_SOURCE_SYS = 0x0

System Clock Source.

enumerator CPUTIMER_CLOCK_SOURCE_INTOSC1 = 0x1

Internal Oscillator 1 Clock Source.

enumerator CPUTIMER_CLOCK_SOURCE_INTOSC2 = 0x2

Internal Oscillator 2 Clock Source.

enumerator CPUTIMER_CLOCK_SOURCE_XTAL = 0x3

External Clock Source.

enum CPUTimer_Prescaler

The following are values that can be passed to CPUTimer_selectClockSource() as the prescaler parameter.

Values:

enumerator CPUTIMER_CLOCK_PRESCALER_1 = 0

Prescaler value of / 1.

enumerator CPUTIMER_CLOCK_PRESCALER_2 = 1

Prescaler value of / 2.

enumerator CPUTIMER_CLOCK_PRESCALER_4 = 2

Prescaler value of / 4.

enumerator CPUTIMER_CLOCK_PRESCALER_8 = 3

Prescaler value of / 8.

enumerator CPUTIMER_CLOCK_PRESCALER_16 = 4

Prescaler value of / 16.

Functions

void CPUTimer_clearOverflowFlag(uint32_t base)

Clears CPU timer overflow flag.

This function clears the CPU timer overflow flag.

Parameters

  • base: is the base address of the timer module.

Return

None.

void CPUTimer_disableInterrupt(uint32_t base)

Disables CPU timer interrupt.

This function disables the CPU timer interrupt.

Parameters

  • base: is the base address of the timer module.

Return

None.

void CPUTimer_enableInterrupt(uint32_t base)

Enables CPU timer interrupt.

This function enables the CPU timer interrupt.

Parameters

  • base: is the base address of the timer module.

Return

None.

void CPUTimer_reloadTimerCounter(uint32_t base)

Reloads CPU timer counter.

This function reloads the CPU timer counter with the values contained in the CPU timer period register.

Parameters

  • base: is the base address of the timer module.

Return

None.

void CPUTimer_stopTimer(uint32_t base)

Stops CPU timer.

This function stops the CPU timer.

Parameters

  • base: is the base address of the timer module.

Return

None.

void CPUTimer_resumeTimer(uint32_t base)

Starts(restarts) CPU timer.

This function starts (restarts) the CPU timer.

Parameters

  • base: is the base address of the timer module.

Note: This function doesn’t reset the timer counter.

Return

None.

void CPUTimer_startTimer(uint32_t base)

Starts(restarts) CPU timer.

This function starts (restarts) the CPU timer.

Parameters

  • base: is the base address of the timer module.

Note: This function reloads the timer counter.

Return

None.

void CPUTimer_setPeriod(uint32_t base, uint32_t periodCount)

Sets CPU timer period.

This function sets the CPU timer period count.

Parameters

  • base: is the base address of the timer module.

  • periodCount: is the CPU timer period count.

Return

None.

uint32_t CPUTimer_getTimerCount(uint32_t base)

Returns the current CPU timer counter value.

This function returns the current CPU timer counter value.

Parameters

  • base: is the base address of the timer module.

Return

Returns the current CPU timer count value.

void CPUTimer_setPreScaler(uint32_t base, uint16_t prescaler)

Set CPU timer pre-scaler value.

This function sets the pre-scaler value for the CPU timer. For every value of (prescaler + 1), the CPU timer counter decrements by 1.

Parameters

  • base: is the base address of the timer module.

  • prescaler: is the CPU timer pre-scaler value.

Return

None.

bool CPUTimer_getTimerOverflowStatus(uint32_t base)

Return the CPU timer overflow status.

This function returns the CPU timer overflow status.

Parameters

  • base: is the base address of the timer module.

Return

Returns true if the CPU timer has overflowed, false if not.

void CPUTimer_selectClockSource(uint32_t base, CPUTimer_ClockSource source, CPUTimer_Prescaler prescaler)

Select CPU Timer 2 Clock Source and Prescaler

This function selects the specified clock source and prescaler value for the CPU timer (CPU timer 2 only).

Parameters

  • base: is the base address of the timer module.

  • source: is the clock source to use for CPU Timer 2

  • prescaler: is the value that configures the selected clock source relative to the system clock

The source parameter can be any one of the following:

  • CPUTIMER_CLOCK_SOURCE_SYS - System Clock

  • CPUTIMER_CLOCK_SOURCE_INTOSC1 - Internal Oscillator 1 Clock

  • CPUTIMER_CLOCK_SOURCE_INTOSC2 - Internal Oscillator 2 Clock

  • CPUTIMER_CLOCK_SOURCE_XTAL - External Clock

The prescaler parameter can be any one of the following:

  • CPUTIMER_CLOCK_PRESCALER_1 - Prescaler value of / 1

  • CPUTIMER_CLOCK_PRESCALER_2 - Prescaler value of / 2

  • CPUTIMER_CLOCK_PRESCALER_4 - Prescaler value of / 4

  • CPUTIMER_CLOCK_PRESCALER_8 - Prescaler value of / 8

  • CPUTIMER_CLOCK_PRESCALER_16 - Prescaler value of / 16

Return

None.

void CPUTimer_setEmulationMode(uint32_t base, CPUTimer_EmulationMode mode)

Sets Emulation mode for CPU timer.

This function sets the behaviour of CPU timer during emulation. Valid values mode are: CPUTIMER_EMULATIONMODE_STOPAFTERNEXTDECREMENT, CPUTIMER_EMULATIONMODE_STOPATZERO and CPUTIMER_EMULATIONMODE_RUNFREE.

Parameters

  • base: is the base address of the timer module.

  • mode: is the emulation mode of the timer.

Return

None.

The code for this module is contained in driverlib/cputimer.c, with driverlib/cputimer.h containing the API declarations for use by applications.