SAM3/4S/4L/4E/4N/4CM/4C/G Timer Counter (TC) Driver

This driver for Atmel® | SMART ARM®-based microcontrollers provides an interface for the configuration and management of the device's Timer Counter functionality.

The Timer Counter (TC) includes several identical 16-bit or 32-bit Timer Counter channels. Each channel can be independently programmed to perform a wide range of functions that includes frequency measurement, event counting, interval measurement, pulse generation, delay timing, and pulse width modulation.

Devices from the following series can use this module:

• Atmel | SMART SAM3
• Atmel | SMART SAM4S
• Atmel | SMART SAM4L
• Atmel | SMART SAM4E
• Atmel | SMART SAM4N
• Atmel | SMART SAM4CM
• Atmel | SMART SAM4C
• Atmel | SMART SAMG

The outline of this documentation is as follows:

• Prerequisites
• Module Overview
• Special Considerations
• Extra Information
• Examples
• API Overview

Prerequisites

There are no prerequisites for this module.

Module Overview

The Timer Counter (TC) includes several identical 16-bit or 32-bit Timer Counter channels. The number of TC channels is device specific, refer to the device-specific datasheet for more information.

Each channel can be independently programmed to perform a wide range of functions that includes frequency measurement, event counting, interval measurement, pulse generation, delay timing, and pulse width modulation.

Each channel has three external clock inputs, five internal clock inputs, and two multi-purpose input/output signals which can be configured by the user. Each channel drives an internal interrupt signal which can be programmed to generate processor interrupts.

The Timer Counter (TC) embeds a quadrature decoder logic connected in front of the timers. When enabled, the quadrature decoder performs the input line filtering, decoding of quadrature signals and connects to the timers/counters in order to read the position and speed of the motor.

Special Considerations

External Clock

In all cases, if an external clock is used, the duration of each of its levels must be longer than the master clock (MCLK) period. The external clock frequency must be at least 2.5 times lower than the master clock.

External Trigger

If an external trigger is used, the duration of its pulses must be longer than the master clock (MCLK) period in order to be detected.

Extra Information

For extra information, see Extra Information for Timer Counter Driver. This includes:

• Acronyms
• Dependencies
• Errata
• Module History

Examples

For a list of examples related to this driver, see Examples for Timer Counter.

API Overview

Functions
void	tc_disable_interrupt (Tc *p_tc, uint32_t ul_channel, uint32_t ul_sources)
	Disable TC interrupts on the specified channel. More...
void	tc_disable_qdec_interrupt (Tc *p_tc, uint32_t ul_sources)
	Disable TC QDEC interrupts. More...
void	tc_enable_interrupt (Tc *p_tc, uint32_t ul_channel, uint32_t ul_sources)
	Enable the TC interrupts on the specified channel. More...
void	tc_enable_qdec_interrupt (Tc *p_tc, uint32_t ul_sources)
	Enable TC QDEC interrupts. More...
uint32_t	tc_find_mck_divisor (uint32_t ul_freq, uint32_t ul_mck, uint32_t *p_uldiv, uint32_t *ul_tcclks, uint32_t ul_boardmck)
	Find the best MCK divisor. More...
uint32_t	tc_get_feature (Tc *p_tc)
	Indicate TC features. More...
uint32_t	tc_get_interrupt_mask (Tc *p_tc, uint32_t ul_channel)
	Read the TC interrupt mask for the specified channel. More...
uint32_t	tc_get_qdec_interrupt_mask (Tc *p_tc)
	Read TC QDEC interrupt mask. More...
uint32_t	tc_get_qdec_interrupt_status (Tc *p_tc)
	Get current TC QDEC interrupt status. More...
uint32_t	tc_get_status (Tc *p_tc, uint32_t ul_channel)
	Get the current status for the specified TC channel. More...
uint32_t	tc_get_version (Tc *p_tc)
	Indicate TC version. More...
void	tc_init (Tc *p_tc, uint32_t ul_Channel, uint32_t ul_Mode)
	Configure TC for timer, waveform generation, or capture. More...
uint32_t	tc_init_2bit_gray (Tc *p_tc, uint32_t ul_channel, uint32_t ul_steppermode)
	Configure TC for 2-bit Gray Counter for Stepper Motor. More...
uint32_t	tc_read_cv (Tc *p_tc, uint32_t ul_channel)
	Read the counter value on the specified channel. More...
uint32_t	tc_read_ra (Tc *p_tc, uint32_t ul_channel)
	Read TC Register A (RA) on the specified channel. More...
uint32_t	tc_read_rb (Tc *p_tc, uint32_t ul_channel)
	Read TC Register B (RB) on the specified channel. More...
uint32_t	tc_read_rc (Tc *p_tc, uint32_t ul_channel)
	Read TC Register C (RC) on the specified channel. More...
void	tc_set_block_mode (Tc *p_tc, uint32_t ul_blockmode)
	Configure the TC Block mode. More...
void	tc_set_writeprotect (Tc *p_tc, uint32_t ul_enable)
	Enable or disable write protection of TC registers. More...
void	tc_start (Tc *p_tc, uint32_t ul_channel)
	Start the TC clock on the specified channel. More...
void	tc_stop (Tc *p_tc, uint32_t ul_channel)
	Stop the TC clock on the specified channel. More...
void	tc_sync_trigger (Tc *p_tc)
	Asserts a SYNC signal to generate a software trigger on all channels. More...
void	tc_write_ra (Tc *p_tc, uint32_t ul_channel, uint32_t ul_value)
	Write to TC Register A (RA) on the specified channel. More...
void	tc_write_rb (Tc *p_tc, uint32_t ul_channel, uint32_t ul_value)
	Write to TC Register B (RB) on the specified channel. More...
void	tc_write_rc (Tc *p_tc, uint32_t ul_channel, uint32_t ul_value)
	Write to TC Register C (RC) on the selected channel. More...

void tc_disable_interrupt	(	Tc *	p_tc,
		uint32_t	ul_channel,
		uint32_t	ul_sources
	)

Disable TC interrupts on the specified channel.

Parameters

[in,out]	p_tc	Module hardware register base address pointer
[in]	ul_channel	Channel to configure
[in]	ul_sources	A bitmask of Interrupt sources

Where the input parameter ul_sources can be one or more of the following:

Parameter Value	Description
TC_IDR_COVFS	Disables the Counter Overflow Interrupt
TC_IDR_LOVRS	Disables the Load Overrun Interrupt
TC_IDR_CPAS	Disables the RA Compare Interrupt
TC_IDR_CPBS	Disables the RB Compare Interrupt
TC_IDR_CPCS	Disables the RC Compare Interrupt
TC_IDR_LDRAS	Disables the RA Load Interrupt
TC_IDR_LDRBS	Disables the RB Load Interrupt
TC_IDR_ETRGS	Disables the External Trigger Interrupt

References Assert.

void tc_disable_qdec_interrupt	(	Tc *	p_tc,
		uint32_t	ul_sources
	)

Disable TC QDEC interrupts.

Note

This function is not available on SAM4L or SAMG devices.

Parameters

[out]	p_tc	Module hardware register base address pointer
[in]	ul_sources	A bitmask of QDEC interrupts to be disabled

Where the input parameter ul_sources can be one or more of the following:

Parameter Value	Description
TC_QIDR_IDX	Disable the rising edge detected on IDX input interrupt
TC_QIDR_DIRCHG	Disable the change in rotation direction detected interrupt
TC_QIDR_QERR	Disable the quadrature error detected on PHA/PHB interrupt

References Assert.

void tc_enable_interrupt	(	Tc *	p_tc,
		uint32_t	ul_channel,
		uint32_t	ul_sources
	)

Enable the TC interrupts on the specified channel.

Parameters

[in,out]	p_tc	Module hardware register base address pointer
[in]	ul_channel	Channel to configure
[in]	ul_sources	Bitmask of interrupt sources

Where the input parameter ul_sources can be one or more of the following:

Parameter Value	Description
TC_IER_COVFS	Enables the Counter Overflow Interrupt
TC_IER_LOVRS	Enables the Load Overrun Interrupt
TC_IER_CPAS	Enables the RA Compare Interrupt
TC_IER_CPBS	Enables the RB Compare Interrupt
TC_IER_CPCS	Enables the RC Compare Interrupt
TC_IER_LDRAS	Enables the RA Load Interrupt
TC_IER_LDRBS	Enables the RB Load Interrupt
TC_IER_ETRGS	Enables the External Trigger Interrupt

References Assert.

Referenced by configure_tc().

void tc_enable_qdec_interrupt	(	Tc *	p_tc,
		uint32_t	ul_sources
	)

Enable TC QDEC interrupts.

Note

This function is not available on SAM4L or SAMG devices.

Parameters

[out]	p_tc	Module hardware register base address pointer
[in]	ul_sources	A bitmask of QDEC interrupts to be enabled

Where the input parameter ul_sources can be one or more of the following:

Parameter Value	Description
TC_QIER_IDX	Enable the rising edge detected on IDX input interrupt
TC_QIER_DIRCHG	Enable the change in rotation direction detected interrupt
TC_QIER_QERR	Enable the quadrature error detected on PHA/PHB interrupt

References Assert.

uint32_t tc_find_mck_divisor	(	uint32_t	ul_freq,
		uint32_t	ul_mck,
		uint32_t *	p_uldiv,
		uint32_t *	p_ultcclks,
		uint32_t	ul_boardmck
	)

Find the best MCK divisor.

Find the best PBA/MCK divisor.

Finds the best MCK divisor given the timer frequency and MCK. The result is guaranteed to satisfy the following equation:

(MCK / (DIV * 65536)) <= freq <= (MCK / DIV) 

With DIV being the lowest possible value, to maximize timing adjust resolution.

Parameters

[in]	ul_freq	Desired timer frequency
[in]	ul_mck	Master clock frequency
[out]	p_uldiv	Divisor value
[out]	p_ultcclks	TCCLKS field value for divisor
[in]	ul_boardmck	Board clock frequency

Returns

The divisor found status.

Return values

0	No suitable divisor was found
1	A divisor was found

For SAM4L devices: Finds the best PBA divisor given the timer frequency and PBA clock. The result is guaranteed to satisfy the following equation:

(ul_pbaclk / (2* DIV * 65536)) <= freq <= (ul_pbaclk / (2* DIV)) 

with DIV being the lowest possible value, to maximize timing adjust resolution.

For non SAM4L devices: Finds the best MCK divisor given the timer frequency and MCK. The result is guaranteed to satisfy the following equation:

(MCK / (DIV * 65536)) <= freq <= (MCK / DIV) 

with DIV being the lowest possible value, to maximize timing adjust resolution.

Parameters

[in]	ul_freq	Desired timer frequency
[in]	ul_mck	PBA clock frequency
[out]	p_uldiv	Divisor value
[out]	p_ultcclks	TCCLKS field value for divisor
[in]	ul_boardmck	Board clock frequency (set to 0 for SAM4L devices)

Returns

The divisor found status.

Return values

0	No suitable divisor was found
1	A divisor was found

References FREQ_SLOW_CLOCK_EXT, and TC_DIV_FACTOR.

Referenced by configure_tc().

uint32_t tc_get_feature

(

Tc *

p_tc

)

Indicate TC features.

Note

This function is only available on SAM4L devices.

Parameters

[in]

p_tc

Module hardware register base address pointer

Returns

The TC FEATURES register contents.

References Assert.

uint32_t tc_get_interrupt_mask	(	Tc *	p_tc,
		uint32_t	ul_channel
	)

Read the TC interrupt mask for the specified channel.

Parameters

[in]	p_tc	Module hardware register base address pointer
[in]	ul_channel	Channel to read

Returns

The TC interrupt mask value.

References Assert.

uint32_t tc_get_qdec_interrupt_mask

(

Tc *

p_tc

)

Read TC QDEC interrupt mask.

Note

This function is not available on SAM4L or SAMG devices.

Parameters

[in]

p_tc

Module hardware register base address pointer

Returns

The QDEC interrupt mask value.

References Assert.

uint32_t tc_get_qdec_interrupt_status

(

Tc *

p_tc

)

Get current TC QDEC interrupt status.

Note

This function is not available on SAM4L or SAMG devices.

Parameters

[in]

p_tc

Module hardware register base address pointer

Returns

The TC QDEC interrupt status.

References Assert.

uint32_t tc_get_status	(	Tc *	p_tc,
		uint32_t	ul_channel
	)

Get the current status for the specified TC channel.

Parameters

[in]	p_tc	Module hardware register base address pointer
[in]	ul_channel	Channel number

Returns

The current TC status.

References Assert.

Referenced by TC00_Handler().

uint32_t tc_get_version

(

Tc *

p_tc

)

Indicate TC version.

Note

This function is only available on SAM4L devices.

Parameters

[in]

p_tc

Module hardware register base address pointer

Returns

The TC VERSION register contents.

References Assert.

void tc_init	(	Tc *	p_tc,
		uint32_t	ul_channel,
		uint32_t	ul_mode
	)

Configure TC for timer, waveform generation, or capture.

Parameters

[in,out]	p_tc	Module hardware register base address pointer
[in]	ul_channel	Channel to configure
[in]	ul_mode	Control mode register bitmask value to set

Note

For more information regarding ul_mode configuration refer to the section entitled "Channel Mode Register: Capture Mode" and/or section "Waveform Operating Mode" in the device-specific datasheet.

If the TC is configured for waveform generation then the external event selection (EEVT) should only be set to TC_CMR_EEVT_TIOB, or the equivalent value of 0, if it really is the intention to use TIOB as an external event trigger. This is because this setting forces TIOB to be an input, even if the external event trigger has not been enabled with TC_CMR_ENETRG, and thus prevents normal operation of TIOB.

References Assert.

Referenced by configure_tc().

uint32_t tc_init_2bit_gray	(	Tc *	p_tc,
		uint32_t	ul_channel,
		uint32_t	ul_steppermode
	)

Configure TC for 2-bit Gray Counter for Stepper Motor.

Note

The function tc_init() must be called prior to this one.

This function is not available on SAM3U devices.

Parameters

[out]	p_tc	Module hardware register base address pointer
[in]	ul_channel	Channel to configure
[in]	ul_steppermode	Stepper motor mode register value to set

Returns

0 for OK.

References Assert.

uint32_t tc_read_cv	(	Tc *	p_tc,
		uint32_t	ul_channel
	)

Read the counter value on the specified channel.

Parameters

[in]	p_tc	Module hardware register base address pointer
[in]	ul_channel	Channel to read

Returns

The counter value.

References Assert.

uint32_t tc_read_ra	(	Tc *	p_tc,
		uint32_t	ul_channel
	)

Read TC Register A (RA) on the specified channel.

Parameters

[in]	p_tc	Module hardware register base address pointer
[in]	ul_channel	Channel to read

Returns

The TC Register A (RA) value.

References Assert.

uint32_t tc_read_rb	(	Tc *	p_tc,
		uint32_t	ul_channel
	)

Read TC Register B (RB) on the specified channel.

Parameters

[in]	p_tc	Module hardware register base address pointer
[in]	ul_channel	Channel to read

Returns

The TC Register B (RB) value.

References Assert.

uint32_t tc_read_rc	(	Tc *	p_tc,
		uint32_t	ul_channel
	)

Read TC Register C (RC) on the specified channel.

Parameters

[in]	p_tc	Module hardware register base address pointer
[in]	ul_channel	Channel to read

Returns

The Register C (RC) value.

References Assert.

void tc_set_block_mode	(	Tc *	p_tc,
		uint32_t	ul_blockmode
	)

Configure the TC Block mode.

Note

The function tc_init() must be called prior to this one.

Parameters

[out]	p_tc	Module hardware register base address pointer
[in]	ul_blockmode	Block mode register value to set

Note

For more information regarding ul_blockmode configuration refer to the section entitled "TC Block Mode Register" in the device-specific datasheet.

References Assert.

void tc_set_writeprotect	(	Tc *	p_tc,
		uint32_t	ul_enable
	)

Enable or disable write protection of TC registers.

Note

This function is not available on SAM3U devices.

Parameters

[out]	p_tc	Module hardware register base address pointer
[in]	ul_enable	1 to enable, 0 to disable

References Assert, and TC_WPMR_WPKEY_PASSWD.

void tc_start	(	Tc *	p_tc,
		uint32_t	ul_channel
	)

Start the TC clock on the specified channel.

Parameters

[out]	p_tc	Module hardware register base address pointer
[in]	ul_channel	Channel to configure

References Assert.

Referenced by main(), and USART_Handler().

void tc_stop	(	Tc *	p_tc,
		uint32_t	ul_channel
	)

Stop the TC clock on the specified channel.

Parameters

[out]	p_tc	Module hardware register base address pointer
[in]	ul_channel	Channel to configure

References Assert.

Referenced by USART_Handler().

void tc_sync_trigger

(

Tc *

p_tc

)

Asserts a SYNC signal to generate a software trigger on all channels.

Parameters

[out]

p_tc

Module hardware register base address pointer

References Assert.

void tc_write_ra	(	Tc *	p_tc,
		uint32_t	ul_channel,
		uint32_t	ul_value
	)

Write to TC Register A (RA) on the specified channel.

Parameters

[out]	p_tc	Module hardware register base address pointer
[in]	ul_channel	Channel to write
[in]	ul_value	Value to write

References Assert.

void tc_write_rb	(	Tc *	p_tc,
		uint32_t	ul_channel,
		uint32_t	ul_value
	)

Write to TC Register B (RB) on the specified channel.

Parameters

[out]	p_tc	Module hardware register base address pointer
[in]	ul_channel	Channel to write
[in]	ul_value	Value to write

References Assert.

void tc_write_rc	(	Tc *	p_tc,
		uint32_t	ul_channel,
		uint32_t	ul_value
	)

Write to TC Register C (RC) on the selected channel.

Parameters

[out]	p_tc	Module hardware register base address pointer
[in]	ul_channel	Channel to write
[in]	ul_value	Value to write

References Assert.

Referenced by configure_tc().