eQEP (enhanced Quadrature Encoder Pulse) support API. More...

Data Structures
struct	bbb_eqep

Macros
#define	AM335X_EQEP_REGS (0x00000180)
#define	AM335X_EQEP_0_REGS (AM335X_PWMSS0_MMAP_ADDR + AM335X_EQEP_REGS)
#define	AM335X_EQEP_1_REGS (AM335X_PWMSS1_MMAP_ADDR + AM335X_EQEP_REGS)
#define	AM335X_EQEP_2_REGS (AM335X_PWMSS2_MMAP_ADDR + AM335X_EQEP_REGS)
#define	AM335x_EQEP_QPOSCNT 0x0
#define	AM335x_EQEP_QPOSINIT 0x4
#define	AM335x_EQEP_QPOSMAX 0x8
#define	AM335x_EQEP_QPOSCMP 0xC
#define	AM335x_EQEP_QPOSILAT 0x10
#define	AM335x_EQEP_QPOSSLAT 0x14
#define	AM335x_EQEP_QPOSLAT 0x18
#define	AM335x_EQEP_QUTMR 0x1C
#define	AM335x_EQEP_QUPRD 0x20
#define	AM335x_EQEP_QWDTMR 0x24
#define	AM335x_EQEP_QWDPRD 0x26
#define	AM335x_EQEP_QDECCTL 0x28
#define	AM335x_EQEP_QEPCTL 0x2A
#define	AM335x_EQEP_QCAPCTL 0x2C
#define	AM335x_EQEP_QPOSCTL 0x2E
#define	AM335x_EQEP_QEINT 0x30
#define	AM335x_EQEP_QFLG 0x32
#define	AM335x_EQEP_QCLR 0x34
#define	AM335x_EQEP_QFRC 0x36
#define	AM335x_EQEP_QEPSTS 0x38
#define	AM335x_EQEP_QCTMR 0x3A
#define	AM335x_EQEP_QCPRD 0x3C
#define	AM335x_EQEP_QCTMRLAT 0x3E
#define	AM335x_EQEP_QCPRDLAT 0x40
#define	AM335x_EQEP_REVID 0x5C
#define	AM335x_EQEP_QEPCTL_UTE (1 << 1)
#define	AM335x_EQEP_QEPCTL_QCLM (1 << 2)
#define	AM335x_EQEP_QEPCTL_PHEN (1 << 3)
#define	AM335x_EQEP_QEPCTL_IEL (1 << 4)
#define	AM335x_EQEP_QEPCTL_SWI (1 << 7)
#define	AM335x_EQEP_QEPCTL_PCRM (3 << 12)
#define	AM335x_EQEP_QDECCTL_QSRC (3 << 14)
#define	AM335x_EQEP_QDECCTL_XCR (1 << 11)
#define	AM335x_EQEP_QDECCTL_SWAP (1 << 10)
#define	AM335x_EQEP_QDECCTL_IGATE (1 << 9)
#define	AM335x_EQEP_QDECCTL_QAP (1 << 8)
#define	AM335x_EQEP_QDECCTL_QBP (1 << 7)
#define	AM335x_EQEP_QDECCTL_QIP (1 << 6)
#define	AM335x_EQEP_QDECCTL_QSP (1 << 5)
#define	AM335x_EQEP_CLK_EN (1 << 4)
#define	AM335x_EQEP_QEINT_UTO (1 << 11)
#define	AM335x_EQEP_QFLG_UTO (1 << 11)
#define	AM335x_EQEP_QFLG_MASK 0x0FFF
#define	BBB_P8_11_MUX_QEP 4
#define	BBB_P8_12_MUX_QEP 4
#define	BBB_P8_15_MUX_QEP 4
#define	BBB_P8_16_MUX_QEP 4
#define	BBB_P8_31_MUX_QEP 2
#define	BBB_P8_32_MUX_QEP 2
#define	BBB_P8_33_MUX_QEP 2
#define	BBB_P8_35_MUX_QEP 2
#define	BBB_P8_39_MUX_QEP 3
#define	BBB_P8_40_MUX_QEP 3
#define	BBB_P8_41_MUX_QEP 3
#define	BBB_P8_42_MUX_QEP 3
#define	BBB_P9_25_MUX_QEP 1
#define	BBB_P9_27_MUX_QEP 1
#define	BBB_P9_41_MUX_QEP 1
#define	BBB_P9_42_MUX_QEP 1
#define	NANO_SEC_PER_SEC 1000000000
#define	SYSCLKOUT 100000000

Typedefs
typedef void(*)	bbb_eqep_timer_callback(BBB_PWMSS, uint32_t position, void *user)
	This function definition is used to declare a callback function that will be called by the interrupt handler of the QEP driver. In order for the interrupt event to trigger the driver must be configured in RELATIVE mode (using the beagle_qep_get_quadrature_mode function), and the unit timer must have been configured (using the beagle_eqep_set_timer_period function).

Enumerations
enum	BBB_QEP_COUNT_MODE { QUADRATURE_COUNT = 0 , DIRECTION_COUNT , UP_COUNT , DOWN_COUNT }
	The set of possible eQEP Position Counter Input Modes. More...
enum	BBB_QEP_QUADRATURE_MODE { ABSOLUTE = 0 , RELATIVE }
	The set of possible modes for Quadrature decode.
enum	bbb_qep_pin { BBB_P8_11_2B_IN , BBB_P8_12_2A_IN , BBB_P8_15_2_STROBE , BBB_P8_16_2_IDX , BBB_P8_31_1_IDX , BBB_P8_32_1_STROBE , BBB_P8_33_1B_IN , BBB_P8_35_1A_IN , BBB_P8_39_2_IDX , BBB_P8_40_2_STROBE , BBB_P8_41_2A_IN , BBB_P8_42_2B_IN , BBB_P9_25_0_STROBE , BBB_P9_27_0B_IN , BBB_P9_41_0_IDX , BBB_P9_42_0A_IN }
	The set of possible eQEP input pins.

Functions
rtems_status_code	beagle_qep_init (BBB_PWMSS pwmss_id)
	Initialises the eQEP module of the specified PWMSS unit. This configures the clocks, sets up the interrupt handler and unit timer, The module is configured in Quadrature decode mode using absolute position by default.
rtems_status_code	beagle_qep_enable (BBB_PWMSS pwmss_id)
	Enables the eQEP module of the specified PWMSS unit.
rtems_status_code	beagle_qep_disable (BBB_PWMSS pwmss_id)
	Disables the eQEP module of the specified PWMSS unit.
rtems_status_code	beagle_qep_pinmux_setup (bbb_qep_pin pin_no, BBB_PWMSS pwmss_id, bool pullup_enable)
	Configures a given pin for use with the eQEP function of the supplied PWMSS module.
int32_t	beagle_qep_get_position (BBB_PWMSS pwmss_id)
	Returns the current position value of the eQEP function for the specified PWMSS module.
rtems_status_code	beagle_qep_set_position (BBB_PWMSS pwmss_id, uint32_t position)
	Sets the initial position value of the eQEP function for the specified PWMSS module.
rtems_status_code	beagle_qep_set_count_mode (BBB_PWMSS pwmss_id, BBB_QEP_COUNT_MODE mode)
	Sets the count mode for the eQEP module.
BBB_QEP_COUNT_MODE	beagle_qep_get_count_mode (BBB_PWMSS pwmss_id)
	Gets the currently configured count mode for the eQEP module.
BBB_QEP_QUADRATURE_MODE	beagle_qep_get_quadrature_mode (BBB_PWMSS pwmss_id)
	Returns the currently configured quadrature mode - either absolute, or relative.
rtems_status_code	beagle_qep_set_quadrature_mode (BBB_PWMSS pwmss_id, BBB_QEP_QUADRATURE_MODE mode)
	Sets the quadrature mode to either absolute or relative.
uint32_t	beagle_eqep_get_timer_period (BBB_PWMSS pwmss_id)
	Returns the the currently configured unit timer period.
rtems_status_code	beagle_eqep_set_timer_period (BBB_PWMSS pwmss_id, uint64_t period, bbb_eqep_timer_callback timer_callback, void *user)
	Sets the unit timer period for the eQEP module. 0 = off, greater than zero sets the period.

Detailed Description

eQEP (enhanced Quadrature Encoder Pulse) support API.

Macro Definition Documentation

◆ AM335X_EQEP_REGS

#define AM335X_EQEP_REGS (0x00000180)

For details of the Enhanced Quadrature Encoder Pulse (eQEP) Module refer to page 2511 of the TI Technical Reference Manual (https://www.ti.com/lit/ug/spruh73q/spruh73q.pdf)

This driver supports using the QEP modules in Quadrature-clock Mode. Direction-count Mode is not currently supported. Similarly the QEPI: Index or Zero Marker and QEPS: Strobe Input pins are not currently supported.

The mode can be any one of:

Quadrature-count mode - For encoders that generate pulses 90 degrees out of phase for determining direction and speed.
Direction-count mode - for position encoders that provide direction and clock outputs, instead of quadrature outputs.
UP-count mode - The counter direction signal is hard-wired for up count and the position counter is used to measure the frequency of the QEPA input.
DOWN-count mode - The counter direction signal is hard-wired for a down count and the position counter is used to measure the frequency of the QEPA input.

When the eQEP module is configured in quadrature mode, the module can either provide an absolute position, or a relative position. Absolute simply increments or decrements depending on the direction. Relative increments until the unit timer overflows at which point it latches the position value, resets the position count to zero and starts again.

Typedef Documentation

◆ bbb_eqep_timer_callback

typedef void(*) bbb_eqep_timer_callback(BBB_PWMSS, uint32_t position, void *user)

This function definition is used to declare a callback function that will be called by the interrupt handler of the QEP driver. In order for the interrupt event to trigger the driver must be configured in RELATIVE mode (using the beagle_qep_get_quadrature_mode function), and the unit timer must have been configured (using the beagle_eqep_set_timer_period function).

Parameters

BBB_PWMSS	This argument is provided to the user call back function so that the user can tell which QEP module raised the interrupt.
position	The value of the position counter that was latched when the unit timer raised this interrupt. This is the value that would be returned by calling "beagle_qep_get_position".
user	This a pointer to a user provided data structure. The user sets this pointer value when configuring the unit timer callback via the beagle_eqep_set_timer_period function and it is returned here as an argument. The driver does not touch this value.

Enumeration Type Documentation

◆ BBB_QEP_COUNT_MODE

enum BBB_QEP_COUNT_MODE

The set of possible eQEP Position Counter Input Modes.

Enumerated type to define various modes for the eQEP module. The values correspond to the values for the QSRC bits of the QDECCTL register.

Function Documentation

◆ beagle_eqep_get_timer_period()

uint32_t beagle_eqep_get_timer_period ( BBB_PWMSS pwmss_id )

Returns the the currently configured unit timer period.

Parameters

pwmss_id Identifies which PWMSS module to get the eQEP timer value for

Returns: uint32_t The current unit timer value in nanoseconds

◆ beagle_eqep_set_timer_period()

rtems_status_code beagle_eqep_set_timer_period	(	BBB_PWMSS	pwmss_id,
		uint64_t	period,
		bbb_eqep_timer_callback	timer_callback,
		void *	user )

Sets the unit timer period for the eQEP module. 0 = off, greater than zero sets the period.

Parameters

pwmss_id	Identifies which PWMSS module to set the eQEP unit timer for.
period	The value in nanoseconds to set the unit timer period to.
timer_callback	This is the user provided callback function that will be called by the interrupt event handler on expiry of the unit timer. The user can provide NULL if they don't require a call back.
user	This is a pointer to a user provided data structure that will be handed back as an argument to the timer callback. The driver does not touch this value.

Returns: RTEMS_SUCCESSFUL if ok, RTEMS_INVALID_ID if an invalid pwmss_id is supplied.

◆ beagle_qep_disable()

rtems_status_code beagle_qep_disable ( BBB_PWMSS pwmss_id )

Disables the eQEP module of the specified PWMSS unit.

Parameters

pwmss_id The PWMSS module which will have the eQEP function disabled.

Returns: RTEMS_SUCCESSFUL if ok, RTEMS_INVALID_ID if an invalid pwmss_id is supplied.

◆ beagle_qep_enable()

rtems_status_code beagle_qep_enable ( BBB_PWMSS pwmss_id )

Enables the eQEP module of the specified PWMSS unit.

Parameters

pwmss_id The PWMSS module which will have the eQEP function enabled.

Returns: RTEMS_SUCCESSFUL if ok, RTEMS_INVALID_ID if an invalid pwmss_id is supplied.

◆ beagle_qep_get_count_mode()

BBB_QEP_COUNT_MODE beagle_qep_get_count_mode ( BBB_PWMSS pwmss_id )

Gets the currently configured count mode for the eQEP module.

Parameters

pwmss_id Identifies which PWMSS module to set the eQEP count mode for.

Returns: An enum value representing the current count mode.

◆ beagle_qep_get_position()

int32_t beagle_qep_get_position ( BBB_PWMSS pwmss_id )

Returns the current position value of the eQEP function for the specified PWMSS module.

Parameters

pwmss_id Identifies which PWMSS module to return the eQEP position for

Returns: int32_t The current position value.

◆ beagle_qep_get_quadrature_mode()

BBB_QEP_QUADRATURE_MODE beagle_qep_get_quadrature_mode ( BBB_PWMSS pwmss_id )

Returns the currently configured quadrature mode - either absolute, or relative.

Parameters

pwmss_id Identifies which PWMSS module to get the eQEP quadrature mode for.

Returns: BBB_QEP_QUADRATURE_MODE The currently configured quadrature mode.

◆ beagle_qep_init()

rtems_status_code beagle_qep_init ( BBB_PWMSS pwmss_id )

Initialises the eQEP module of the specified PWMSS unit. This configures the clocks, sets up the interrupt handler and unit timer, The module is configured in Quadrature decode mode using absolute position by default.

Parameters

pwmss_id The PWMSS module to configure the eQEP for.

Returns: RTEMS_SUCCESSFUL if ok, RTEMS_INVALID_ID if an invalid pwmss_id is supplied.

◆ beagle_qep_pinmux_setup()

rtems_status_code beagle_qep_pinmux_setup	(	bbb_qep_pin	pin_no,
		BBB_PWMSS	pwmss_id,
		bool	pullup_enable )

Configures a given pin for use with the eQEP function of the supplied PWMSS module.

Parameters

pin_no	The P9 or P8 header pin to be configured for the eQEP function.
pwmss_id	The PWMSS module which will have the eQEP function enabled.
pullup_enable	If true then the internal pull up resistor on the specified pin will be enabled, if false the pull down will be enabled.

Returns: RTEMS_SUCCESSFUL if ok, RTEMS_INVALID_ID if an invalid pwmss_id is supplied.

◆ beagle_qep_set_count_mode()

rtems_status_code beagle_qep_set_count_mode	(	BBB_PWMSS	pwmss_id,
		BBB_QEP_COUNT_MODE	mode )

Sets the count mode for the eQEP module.

Parameters

pwmss_id	Identifies which PWMSS module to set the eQEP count mode for.
mode	One of the above modes to configure the eQEP module for.

Returns: RTEMS_SUCCESSFUL if ok, RTEMS_INVALID_ID if an invalid pwmss_id is supplied.

◆ beagle_qep_set_position()

rtems_status_code beagle_qep_set_position	(	BBB_PWMSS	pwmss_id,
		uint32_t	position )

Sets the initial position value of the eQEP function for the specified PWMSS module.

Parameters

pwmss_id	Identifies which PWMSS module to set the eQEP position for
position	The value to initialise the position register with.

Returns: RTEMS_SUCCESSFUL if ok, RTEMS_INVALID_ID if an invalid pwmss_id is supplied.

◆ beagle_qep_set_quadrature_mode()

rtems_status_code beagle_qep_set_quadrature_mode	(	BBB_PWMSS	pwmss_id,
		BBB_QEP_QUADRATURE_MODE	mode )

Sets the quadrature mode to either absolute or relative.

Parameters

pwmss_id	Identifies which PWMSS module to set the eQEP quadrature mode for.
mode	BBB_QEP_QUADRATURE_MODE Set the mode of the eQEP to either absolute or relative.

Returns: RTEMS_SUCCESSFUL if ok, RTEMS_INVALID_ID if an invalid pwmss_id is supplied.

Data Structures

Macros

Typedefs

Enumerations

Functions

Detailed Description

Macro Definition Documentation

◆ AM335X_EQEP_REGS

Typedef Documentation

◆ bbb_eqep_timer_callback

Enumeration Type Documentation

◆ BBB_QEP_COUNT_MODE

Function Documentation

◆ beagle_eqep_get_timer_period()

◆ beagle_eqep_set_timer_period()

◆ beagle_qep_disable()

◆ beagle_qep_enable()

◆ beagle_qep_get_count_mode()

◆ beagle_qep_get_position()

◆ beagle_qep_get_quadrature_mode()

◆ beagle_qep_init()

◆ beagle_qep_pinmux_setup()

◆ beagle_qep_set_count_mode()

◆ beagle_qep_set_position()

◆ beagle_qep_set_quadrature_mode()