Overview

This section describes the programming interface of the FlexTimer Peripheral driver.

FlexTimer Overview

The FlexTimer module is a timer that supports input capture, output compare, and generation of PWM signals. The current Kinetis SDK driver only supports the generation of PWM signals. The input capture and output compare will be supported in upcoming Kinetis SDK releases.

FlexTimer Initialization

To initialize the FlexTimer driver, call the FTM_DRV_Init() function and pass the instance number of the relevant FTM. For example, to use FTM0, pass a value of 0 to the initialization function.
Pass a user configuration structure ftm_user_config_t, as shown here:

// FTM configuration structure
typedef struct FtmUserConfig {
    uint8_t tofFrequency;
    bool isFTMMode;
    uint8_t BDMMode;
    bool isWriteProtection;
    bool isTimerOverFlowInterrupt;
    bool isFaultInterrupt;
} ftm_user_config_t;

FlexTimer Generate a PWM signal

FTM calls the FTM_DRV_PwmStart() function to generate a PWM signal. Use this structure to configure different parameters for the PWM signal.

typedef struct FtmPwmParam
{
    ftm_config_mode_t mode;               
    ftm_pwm_edge_mode_t edgeMode; 
    uint32_t uFrequencyHZ;                  
    uint32_t uDutyCyclePercent;           
                                          0 = inactive signal(0% duty cycle)...
                                          100 = active signal (100% duty cycle). //
    uint16_t uFirstEdgeDelayPercent;     
                                          Specifies the delay to the first edge in a PWM period.
                                          If unsure leave as 0. Should be specified as
                                          percentage of the PWM period//
} ftm_pwm_param_t;

The mode options are kFtmEdgeAlignedPWM, kFtmCenterAlignedPWM, and kFtmCombinedPWM. For edge mode, the options available are kFtmHighTrue and kFtmLowTrue. Specify the PWM signal frequency in Hz and the duty cycle percentage (value between 0-100). If the PWM mode is kFtmCombinedPWM and if the user chooses to specify a value for the uFirstEdgeDelayPercent, start of the PWM pulse is delayed.

Data Structures
struct	ftm_user_config_t
	Configuration structure that the user needs to set. More...

Functions
ftm_status_t	FTM_DRV_Init (uint32_t instance, const ftm_user_config_t *info)
	Initializes the FTM driver. More...

void	FTM_DRV_Deinit (uint32_t instance)
	Shuts down the FTM driver. More...

void	FTM_DRV_PwmStop (uint32_t instance, ftm_pwm_param_t *param, uint8_t channel)
	Stops the channel PWM. More...

ftm_status_t	FTM_DRV_PwmStart (uint32_t instance, ftm_pwm_param_t *param, uint8_t channel)
	Configures the duty cycle and frequency and starts outputting the PWM on a specified channel . More...

void	FTM_DRV_QuadDecodeStart (uint32_t instance, ftm_phase_params_t phaseAParams, ftm_phase_params_t phaseBParams, ftm_quad_decode_mode_t quadMode)
	Configures the parameters and activates the quadrature decode mode. More...

void	FTM_DRV_QuadDecodeStop (uint32_t instance)
	Deactivates the quadrature decode mode. More...

void	FTM_DRV_CounterStart (uint32_t instance, ftm_counting_mode_t countMode, uint32_t countStartVal, uint32_t countFinalVal, bool enableOverflowInt)
	Starts the FTM counter. More...

void	FTM_DRV_CounterStop (uint32_t instance)
	Stops the FTM counter. More...

uint32_t	FTM_DRV_CounterRead (uint32_t instance)
	Reads back the current value of the FTM counter. More...

void	FTM_DRV_SetClock (uint8_t instance, ftm_clock_source_t clock, ftm_clock_ps_t clockPs)
	Sets the FTM clock source. More...

uint32_t	FTM_DRV_GetClock (uint8_t instance)
	Retrieves the frequency of the clock source feeding the FTM counter. More...

void	FTM_DRV_SetTimeOverflowIntCmd (uint32_t instance, bool overflowEnable)
	Enables or disables the timer overflow interrupt. More...

void	FTM_DRV_SetFaultIntCmd (uint32_t instance, bool faultEnable)
	Enables or disables the fault interrupt. More...

void	FTM_DRV_SetupChnInputCapture (uint32_t instance, ftm_input_capture_edge_mode_t captureMode, uint8_t channel, uint8_t filterVal)
	Enables capturing an input signal on the channel using the function parameters. More...

void	FTM_DRV_SetupChnOutputCompare (uint32_t instance, ftm_output_compare_edge_mode_t compareMode, uint8_t channel, uint32_t compareVal)
	Configures the FTM to generate timed pulses. More...

void	FTM_DRV_SetupChnDualEdgeCapture (uint32_t instance, ftm_dual_edge_capture_param_t *param, uint8_t channel, uint8_t filterVal)
	Configures the dual edge capture mode of the FTM. More...

void	FTM_DRV_IRQHandler (uint32_t instance)
	Action to take when an FTM interrupt is triggered. More...

Variables
FTM_Type *const	g_ftmBase [FTM_INSTANCE_COUNT]
	Table of base addresses for FTM instances. More...

const IRQn_Type	g_ftmIrqId [FTM_INSTANCE_COUNT]
	Table to save FTM IRQ enumeration numbers defined in the CMSIS header file. More...

Data Structure Documentation

struct ftm_user_config_t

Data Fields
uint8_t	tofFrequency
	Select ratio between number of overflows to times TOF is set.

ftm_bdm_mode_t	BDMMode
	Select FTM behavior in BDM mode.

bool	isWriteProtection
	true: enable write protection, false: write protection is disabled

uint32_t	syncMethod
	Register synch options available in the ftm_sync_method_t enumeration.

Function Documentation

ftm_status_t FTM_DRV_Init	(	uint32_t	instance,
		const ftm_user_config_t *	info
	)

Parameters

instance	The FTM peripheral instance number.
info	The FTM user configuration structure, see ftm_user_config_t.

Returns: kStatusFtmSuccess means success. Otherwise means failure.

void FTM_DRV_Deinit ( uint32_t instance )

Parameters

instance The FTM peripheral instance number.

void FTM_DRV_PwmStop	(	uint32_t	instance,
		ftm_pwm_param_t *	param,
		uint8_t	channel
	)

Parameters

instance	The FTM peripheral instance number.
param	FTM driver PWM parameter to configure PWM options
channel	The channel number. In combined mode, the code finds the channel pair associated with the channel number passed in.

ftm_status_t FTM_DRV_PwmStart	(	uint32_t	instance,
		ftm_pwm_param_t *	param,
		uint8_t	channel
	)

Parameters

instance	The FTM peripheral instance number.
param	FTM driver PWM parameter to configure PWM options
channel	The channel number. In combined mode, the code finds the channel pair associated with the channel number passed in.

Returns: kStatusFtmSuccess if the PWM setup was successful, kStatusFtmError on failure as the PWM counter is disabled

void FTM_DRV_QuadDecodeStart	(	uint32_t	instance,
		ftm_phase_params_t *	phaseAParams,
		ftm_phase_params_t *	phaseBParams,
		ftm_quad_decode_mode_t	quadMode
	)

Parameters

instance	Instance number of the FTM module.
phaseAParams	Phase A configuration parameters
phaseBParams	Phase B configuration parameters
quadMode	Selects encoding mode used in quadrature decoder mode

void FTM_DRV_QuadDecodeStop ( uint32_t instance )

Parameters

instance Instance number of the FTM module.

void FTM_DRV_CounterStart	(	uint32_t	instance,
		ftm_counting_mode_t	countMode,
		uint32_t	countStartVal,
		uint32_t	countFinalVal,
		bool	enableOverflowInt
	)

This function provides access to the FTM counter. The counter can be run in up-counting and up-down counting modes. To run the counter in free running mode, choose the up-counting option and provide 0x0 for the countStartVal and 0xFFFF for countFinalVal.

Parameters

instance	The FTM peripheral instance number.
countMode	The FTM counter mode defined by ftm_counting_mode_t.
countStartVal	The starting value that is stored in the CNTIN register.
countFinalVal	The final value that is stored in the MOD register.
enableOverflowInt	true: enable timer overflow interrupt; false: disable

void FTM_DRV_CounterStop ( uint32_t instance )

Parameters

instance The FTM peripheral instance number.

uint32_t FTM_DRV_CounterRead ( uint32_t instance )

Parameters

instance The FTM peripheral instance number.

Returns: The counter value.

void FTM_DRV_SetClock	(	uint8_t	instance,
		ftm_clock_source_t	clock,
		ftm_clock_ps_t	clockPs
	)

This function saves the user's clock source selection in the driver to set the clock source and use features provided by the driver-like counter, PWM generation, and so on. This function also sets the clock divider.

Parameters

instance	The FTM peripheral instance number.
clock	The clock source to use, cannot pick None.
clockPs	The clock divider value.

uint32_t FTM_DRV_GetClock ( uint8_t instance )

This function returns zero if no clock source is selected and the FTM counter is disabled.

Parameters

instance The FTM peripheral instance number.

Returns: The frequency of the clock source running the FTM counter, returns 0 if counter is disabled

void FTM_DRV_SetTimeOverflowIntCmd	(	uint32_t	instance,
		bool	overflowEnable
	)

Parameters

instance	The FTM peripheral instance number.
overflowEnable	true: enable the timer overflow interrupt, false: disable

void FTM_DRV_SetFaultIntCmd	(	uint32_t	instance,
		bool	faultEnable
	)

Parameters

instance	The FTM peripheral instance number.
faultEnable	true: enable the fault interrupt, false: disable

void FTM_DRV_SetupChnInputCapture	(	uint32_t	instance,
		ftm_input_capture_edge_mode_t	captureMode,
		uint8_t	channel,
		uint8_t	filterVal
	)

When the edge specified in the captureMode argument occurs on the channel, the FTM counter is captured into the CnV register. The user has to read the CnV register separately to get this value. The filter function is disabled if the filterVal argument passed in is 0. The filter function is available only for 0, 1, 2, 3 channels.

Parameters

instance	The FTM peripheral instance number
captureMode	Specifies which edge to capture
channel	The channel number
filterVal	Filter value to be used, specify 0 to disable filter. Available only for channels 0-3

void FTM_DRV_SetupChnOutputCompare	(	uint32_t	instance,
		ftm_output_compare_edge_mode_t	compareMode,
		uint8_t	channel,
		uint32_t	compareVal
	)

When the FTM counter matches the value of compareVal argument (this is written into CnV reg), the channel output is changed based on what is specified in the compareMode argument.

Parameters

instance	The FTM peripheral instance number.
compareMode	Action to take on the channel output when the compare condition is met
channel	The channel number
compareVal	Value to be programmed in the CnV register.

void FTM_DRV_SetupChnDualEdgeCapture	(	uint32_t	instance,
		ftm_dual_edge_capture_param_t *	param,
		uint8_t	channel,
		uint8_t	filterVal
	)

This function sets up the dual edge capture mode on a channel pair. The capture edge for the channel pair and the capture mode (one-shot or continuous) is specified in the parameter argument. The filter function is disabled if the filterVal argument passed is zero. The filter function is available only on channels 0 and 2. The user has to read the channel CnV registers separately to get the capture values.

Parameters

instance	The FTM peripheral instance number.
param	Controls the dual edge capture function
channel	The channel number, the code finds the channel pair associated with the channel number passed in.
filterVal	Filter value to be used, specify 0 to disable filter. Available only for channels 0, 2

void FTM_DRV_IRQHandler ( uint32_t instance )

The timer overflow flag is checked and cleared if set.

Parameters

instance Instance number of the FTM module.

Variable Documentation

FTM_Type* const g_ftmBase[FTM_INSTANCE_COUNT]

const IRQn_Type g_ftmIrqId[FTM_INSTANCE_COUNT]

Overview

FlexTimer Overview

FlexTimer Initialization

FlexTimer Generate a PWM signal

Data Structures

Functions

Variables

Data Structure Documentation

Data Fields

Function Documentation

Variable Documentation