Timer (Timer/Counter)

General Description

High level interface for interacting with the Timer/Counter hardware resource.

The timer block is commonly used to measure the time of occurrence of an event, to measure the time difference between two events or perform an action after a specified period of time. The driver also allows the user to invoke a callback function when a particular event occurs.

Some use case scenarios of timer -

• Creating a periodic interrupt for executing periodic tasks
• Measuring time between two events
• Triggering other system resources after a certain number of events
• Capturing time stamps when events occur

Features

• Runtime configurable parameters like period and compare value
• Configurable counting direction
• Interrupt on various events
• Continuous or One Shot run modes

Quick Start

See Snippet 1: Measuring time of an operation.

Code Snippets

Snippet 1: Measuring time of an operation

The following snippet initializes a Timer and measures the time between two events. The clock will be defined in design.modus, and can be over-ridden with the mtb_hal_timer_setup() call.

    cy_rslt_t rslt;
    uint32_t  read_val;
 
    /* Use the device-configurator output for the alias "timer" */
    rslt = Cy_TCPWM_Counter_Init(timer_HW, timer_NUM, &timer_config);
    if (rslt == CY_RSLT_SUCCESS)
    {
        rslt = mtb_hal_timer_setup(&my_timer, &timer_hal_config, NULL);
        if (rslt == CY_RSLT_SUCCESS)
        {
            Cy_TCPWM_Counter_Enable(timer_HW, timer_NUM);
        }
    }
 
    if (rslt == CY_RSLT_SUCCESS)
    {
        // Start the timer with the configured settings
        rslt = mtb_hal_timer_start(&my_timer);
    }
 
    // Delay Function simulates the time between two events
    mtb_hal_system_delay_ms(500);
 
    // Read the current timer value, which should be close to the amount of delay in ms * 10 (5000)
    read_val = mtb_hal_timer_read(&my_timer);

Snippet 2: Handling an event in a callback function

The following snippet initializes a Timer and triggers an event after every one second. The clock will be defined in design.modus, and can be over-ridden with the mtb_hal_timer_setup() call.

 
/*
 * Timer event handler - called from mtb_hal_timer_process_interrupt()
 */
void my_timer_irq_handler(void* arg, mtb_hal_timer_event_t event)
{
    (void)arg;
    (void)event;
}
 
 
cy_rslt_t snippet_mtb_hal_timer_event_interrupt(void)
{
    cy_rslt_t rslt;
 
    /* Use the device-configurator output for the alias "timer" */
    rslt = Cy_TCPWM_Counter_Init(timer_HW, timer_NUM, &timer_config);
    if (rslt == CY_RSLT_SUCCESS)
    {
        rslt = mtb_hal_timer_setup(&my_timer, &timer_hal_config, NULL);
        if (rslt == CY_RSLT_SUCCESS)
        {
            Cy_TCPWM_Counter_Enable(timer_HW, timer_NUM);
        }
    }
 
    // Enable System IRQ
    if (rslt == CY_RSLT_SUCCESS)
    {
        uint32_t savedIntrStatus = mtb_hal_system_critical_section_enter();
 
        // Enable IRQ
        cy_stc_sysint_t intr_cfg;
        #if defined (CY_IP_M7CPUSS)
        intr_cfg.intrSrc =  _mtb_hal_get_intSrc(timer_IRQ);
        #else
        intr_cfg.intrSrc = (IRQn_Type)_mtb_hal_get_intSrc(timer_IRQ);
        #endif
        intr_cfg.intrPriority = 7u;
 
        // Register system callback
        Cy_SysInt_Init(&intr_cfg, my_test_sys_irq_handler);
        NVIC_EnableIRQ((IRQn_Type)_mtb_hal_get_intVec(timer_IRQ));
 
        mtb_hal_system_critical_section_exit(savedIntrStatus);
    }
 
    // Register the Callback and enable the events
    if (CY_RSLT_SUCCESS == rslt)
    {
        /* set up pointer to our timer before enabling interrupts */
        my_timer_ptr = &my_timer;
 
        // Assign the ISR to execute on timer interrupt
        mtb_hal_timer_register_callback(&my_timer, my_timer_irq_handler, NULL);
 
        // Set the event on which timer interrupt occurs and enable it
        mtb_hal_timer_enable_event(&my_timer, MTB_HAL_TIMER_EVENT_TERMINAL_COUNT, true);
    }
 
    // Start the timer
    if (rslt == CY_RSLT_SUCCESS)
    {
        rslt = mtb_hal_timer_start(&my_timer);
    }
 
    // Delay to allow interrupt to happen
    mtb_hal_system_delay_ms(1000);
 
 
    return rslt;
}
 
 

API Reference
	Timer HAL Results
	Timer specific return codes.

Typedefs
typedef void(*	mtb_hal_timer_event_callback_t) (void *callback_arg, mtb_hal_timer_event_t event)
	Handler for timer events, callback_arg is a pointer to the timer obj.

Enumerations
enum	mtb_hal_timer_event_t {   MTB_HAL_TIMER_EVENT_NONE = (MTB_HAL_MAP_TIMER_EVENT_NONE) ,   MTB_HAL_TIMER_EVENT_TERMINAL_COUNT = (MTB_HAL_MAP_TIMER_EVENT_TERMINAL_COUNT) ,   MTB_HAL_TIMER_EVENT_COMPARE_CC0 = (MTB_HAL_MAP_TIMER_EVENT_COMPARE_CC0) ,   MTB_HAL_TIMER_EVENT_COMPARE_CC0_OR_TERMINAL_COUNT = (MTB_HAL_MAP_TIMER_EVENT_COMPARE_CC0_OR_TERMINAL_COUNT) ,   MTB_HAL_TIMER_EVENT_COMPARE_CC1 = (MTB_HAL_MAP_TIMER_EVENT_COMPARE_CC1) ,   MTB_HAL_TIMER_EVENT_ALL = (MTB_HAL_MAP_TIMER_EVENT_ALL) }
	HAL Timer events. More...

Functions
cy_rslt_t	mtb_hal_timer_setup (mtb_hal_timer_t *obj, const mtb_hal_timer_configurator_t *config, mtb_hal_clock_t *clock)
	Sets up a HAL instance to use the specified hardware resource. More...
cy_rslt_t	mtb_hal_timer_start (mtb_hal_timer_t *obj)
	Starts the timer/counter with the pre-set configuration. More...
cy_rslt_t	mtb_hal_timer_stop (mtb_hal_timer_t *obj)
	Stops the timer/counter. More...
cy_rslt_t	mtb_hal_timer_reset (mtb_hal_timer_t *obj, uint32_t start_value)
	Reset the timer/counter value. More...
uint32_t	mtb_hal_timer_read (const mtb_hal_timer_t *obj)
	Reads the current value from the timer/counter See Snippet 1: Measuring time of an operation. More...
void	mtb_hal_timer_register_callback (mtb_hal_timer_t *obj, mtb_hal_timer_event_callback_t callback, void *callback_arg)
	Register a timer/counter callback handler More...
void	mtb_hal_timer_enable_event (mtb_hal_timer_t *obj, mtb_hal_timer_event_t event, bool enable)
	Configure timer/counter event enablement More...
cy_rslt_t	mtb_hal_timer_process_interrupt (mtb_hal_timer_t *obj)
	Process interrupts related related to a Timer instance. More...

Enumeration Type Documentation

mtb_hal_timer_event_t

enum mtb_hal_timer_event_t

HAL Timer events.

Enumerator
MTB_HAL_TIMER_EVENT_NONE	No event.
MTB_HAL_TIMER_EVENT_TERMINAL_COUNT	Timer Event Terminal Count = (timer reached max count),.
MTB_HAL_TIMER_EVENT_COMPARE_CC0	Timer Event Compare Count 0 = (timer reached compare 0 count),.
MTB_HAL_TIMER_EVENT_COMPARE_CC0_OR_TERMINAL_COUNT	Timer Event Compare Count 0 -or- Terminal Count.
MTB_HAL_TIMER_EVENT_COMPARE_CC1	Timer Event Compare Count 1 = (timer reached compare 1 count),.
MTB_HAL_TIMER_EVENT_ALL	All Timer Events Combined.

Function Documentation

mtb_hal_timer_setup()

cy_rslt_t mtb_hal_timer_setup	(	mtb_hal_timer_t *	obj,
		const mtb_hal_timer_configurator_t *	config,
		mtb_hal_clock_t *	clock
	)

Sets up a HAL instance to use the specified hardware resource.

This hardware resource must have already been configured via the PDL.

Parameters

[out]	obj	The HAL driver instance object. The caller must allocate the memory for this object, but the HAL will initialize its contents
[in]	config	The configurator-generated HAL config structure for this peripheral instance
[in]	clock	The HAL clock object that is connected to this peripheral instance

Returns

the status of the HAL setup

mtb_hal_timer_start()

cy_rslt_t mtb_hal_timer_start

(

mtb_hal_timer_t *

obj

)

Starts the timer/counter with the pre-set configuration.

This does not reset the counter. The count value will start from the value that was set by the last operation to modify it. See Snippet 1: Measuring time of an operation.

Parameters

[in]

obj

The timer/counter object

Returns

The status of the start request

mtb_hal_timer_stop()

cy_rslt_t mtb_hal_timer_stop

(

mtb_hal_timer_t *

obj

)

Stops the timer/counter.

Does not reset counter value.

Parameters

[in]

obj

The timer/counter object

Returns

The status of the stop request

mtb_hal_timer_reset()

cy_rslt_t mtb_hal_timer_reset	(	mtb_hal_timer_t *	obj,
		uint32_t	start_value
	)

Reset the timer/counter value.

Parameters

[in]	obj	The timer/counter object
[in]	start_value	Start value for the timer.

Returns

The status of the reset request

mtb_hal_timer_read()

uint32_t mtb_hal_timer_read

(

const mtb_hal_timer_t *

obj

)

Reads the current value from the timer/counter
See Snippet 1: Measuring time of an operation.

Parameters

[in]

obj

The timer/counter object

Returns

The current value of the timer/counter

mtb_hal_timer_register_callback()

void mtb_hal_timer_register_callback	(	mtb_hal_timer_t *	obj,
		mtb_hal_timer_event_callback_t	callback,
		void *	callback_arg
	)

Register a timer/counter callback handler

This function will be called when one of the events enabled by mtb_hal_timer_enable_event occurs.

See Snippet 2: Handling an event in a callback function.

Parameters

[in]	obj	The timer/counter object
[in]	callback	The callback handler which will be invoked when the event occurs
[in]	callback_arg	Generic argument that will be provided to the callback when called

mtb_hal_timer_enable_event()

void mtb_hal_timer_enable_event	(	mtb_hal_timer_t *	obj,
		mtb_hal_timer_event_t	event,
		bool	enable
	)

Configure timer/counter event enablement

When an enabled event occurs, the function specified by mtb_hal_timer_register_callback will be called.

See Snippet 2: Handling an event in a callback function.

Parameters

[in]	obj	The timer/counter object
[in]	event	The timer/counter event mtb_hal_timer_event_t
[in]	enable	True to turn on interrupts, False to turn off

mtb_hal_timer_process_interrupt()

cy_rslt_t mtb_hal_timer_process_interrupt

(

mtb_hal_timer_t *

obj

)

Process interrupts related related to a Timer instance.

Parameters

obj	HAL object for which the interrupt should be processed

Returns

CY_RSLT_SUCCESS if the interrupt was processed successfully; otherwise an error