PWM (Pulse Width Modulator)

General Description

High level interface for interacting with the pulse width modulator (PWM) hardware resource.

The PWM driver can be used to generate periodic digital waveforms with configurable frequency and duty cycle. The driver allows assigning the PWM output and an optional inverted output to supplied pins. The driver supports interrupt generation on PWM terminal count and compare events.

Features

• Configurable pin assignment for the PWM output
• Optional complementary (inverted) PWM output to a second pin
• Configurable dead time between normal and inverted PWM outputs
• Configurable alignment: left, right or center
• Continuous or One-shot operation
• Option to instantiate and use a new clock or use pre-allocated clock for clock input
• Configurable interrupt and callback assignment on PWM events: terminal count, compare match or combination of both

Quick Start

See Snippet 1: Simple PWM initialization and output to pin for a code snippet that generates a signal with the specified frequency and duty cycle on the specified pin.

Code snippets

Snippet 1: Simple PWM initialization and output to pin

The clock parameter clk is optional and need not be provided (NULL), to generate and use an available clock resource with a default frequency.
The clock frequency and the duty cycle is set using mtb_hal_pwm_set_period.
mtb_hal_pwm_start starts the PWM output on the pin.

    cy_rslt_t        rslt;
    mtb_hal_pwm_t    pwm_obj;
    // Specify the clock source
    mtb_hal_clock_t pwm_clock;
 
    // Initialize the PWM configuration structure
    const cy_stc_tcpwm_pwm_config_t pwm_config = { 0 };
 
    // Initialize PWM
    rslt = (cy_rslt_t)Cy_TCPWM_PWM_Init(PWM_HW, PWM_CNTNUM, &pwm_config);
    rslt = mtb_hal_pwm_setup(&pwm_obj, &PWM_hal_cfg, &pwm_clock);
 
    // Set a 10us pulse with 100us period
    rslt = mtb_hal_pwm_set_period(&pwm_obj, 100, 10);
 
    // Start the PWM output
    rslt = mtb_hal_pwm_start(&pwm_obj);

Snippet 2: Starting and stopping the PWM output

mtb_hal_pwm_start and mtb_hal_pwm_stop functions can be used after PWM initialization to start and stop the PWM output.

    mtb_hal_pwm_t pwm_obj;
    // Specify the clock source
    mtb_hal_clock_t pwm_clock;
    const cy_stc_tcpwm_pwm_config_t pwm_config = { 0 };
 
    // Initialize PWM
    rslt = (cy_rslt_t)Cy_TCPWM_PWM_Init(PWM_HW, PWM_CNTNUM, &pwm_config);
    CY_ASSERT(CY_RSLT_SUCCESS == rslt);
    rslt = mtb_hal_pwm_setup(&pwm_obj, &PWM_hal_cfg, &pwm_clock);
    CY_ASSERT(CY_RSLT_SUCCESS == rslt);
 
    // Set a 10us pulse with 100us period
    rslt = mtb_hal_pwm_set_period(&pwm_obj, 100, 10);
 
    while (loop)
    {
        // Stop the PWM output
        rslt = mtb_hal_pwm_stop(&pwm_obj);
 
        // Delay for observing the output
        mtb_hal_system_delay_ms(5000);
 
        // (Re-)start the PWM output
        rslt = mtb_hal_pwm_start(&pwm_obj);
 
        // Delay for observing the output
        mtb_hal_system_delay_ms(5000);
    }

API Reference
	PWM HAL Results
	PWM specific return codes.

Functions
cy_rslt_t	mtb_hal_pwm_setup (mtb_hal_pwm_t *obj, const mtb_hal_pwm_configurator_t *config, const mtb_hal_clock_t *clock)
	Sets up a HAL instance to use the specified hardware resource. More...
cy_rslt_t	mtb_hal_pwm_set_period (mtb_hal_pwm_t *obj, uint32_t period_us, uint32_t pulse_width_us)
	Set the number of microseconds for the PWM period & pulse width. More...
cy_rslt_t	mtb_hal_pwm_start (mtb_hal_pwm_t *obj)
	Starts the PWM generation and outputs on pin and compl_pin. More...
cy_rslt_t	mtb_hal_pwm_stop (mtb_hal_pwm_t *obj)
	Stops the PWM generation and outputs on pin and compl_pin. More...

Function Documentation

mtb_hal_pwm_setup()

cy_rslt_t mtb_hal_pwm_setup	(	mtb_hal_pwm_t *	obj,
		const mtb_hal_pwm_configurator_t *	config,
		const 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_pwm_set_period()

cy_rslt_t mtb_hal_pwm_set_period	(	mtb_hal_pwm_t *	obj,
		uint32_t	period_us,
		uint32_t	pulse_width_us
	)

Set the number of microseconds for the PWM period & pulse width.

Parameters

[in]	obj	The PWM object
[in]	period_us	The period in microseconds
[in]	pulse_width_us	The pulse width in microseconds

Returns

The status of the period request

mtb_hal_pwm_start()

cy_rslt_t mtb_hal_pwm_start

(

mtb_hal_pwm_t *

obj

)

Starts the PWM generation and outputs on pin and compl_pin.

Parameters

[in]

obj

The PWM object

Returns

The status of the start request

mtb_hal_pwm_stop()

cy_rslt_t mtb_hal_pwm_stop

(

mtb_hal_pwm_t *

obj

)

Stops the PWM generation and outputs on pin and compl_pin.

Parameters

[in]

obj

The PWM object

Returns

The status of the stop request