Segment LCD driver

Functions for configuring and using the SAM L22's Segment LCD peripheral. More...

Enumerations
enum	slcd_bias_value_t { SLCD_BIAS_STATIC = 0 , SLCD_BIAS_HALF = 1 , SLCD_BIAS_THIRD = 2 , SLCD_BIAS_FOURTH = 3 }
enum	slcd_duty_value_t {   SLCD_DUTY_1_COMMON = 0 , SLCD_DUTY_2_COMMON = 1 , SLCD_DUTY_3_COMMON = 2 , SLCD_DUTY_4_COMMON = 3 ,   SLCD_DUTY_6_COMMON = 4 , SLCD_DUTY_8_COMMON = 5 }
enum	slcd_prescaler_value_t { SLCD_PRESCALER_DIV16 = 0 , SLCD_PRESCALER_DIV32 = 1 , SLCD_PRESCALER_DIV64 = 2 , SLCD_PRESCALER_DIV128 = 3 }
enum	slcd_clocksource_value_t { SLCD_CLOCKSOURCE_ULP = 0 , SLCD_CLOCKSOURCE_XOSC = 1 }
enum	slcd_clockdiv_value_t {   SLCD_CLOCKDIV_1 = 0 , SLCD_CLOCKDIV_2 = 1 , SLCD_CLOCKDIV_3 = 2 , SLCD_CLOCKDIV_4 = 3 ,   SLCD_CLOCKDIV_5 = 4 , SLCD_CLOCKDIV_6 = 5 , SLCD_CLOCKDIV_7 = 6 , SLCD_CLOCKDIV_8 = 7 }
enum	slcd_csrshift_value_t { SLCD_CSRSHIFT_LEFT = 0 , SLCD_CSRSHIFT_RIGHT = 1 }

Functions
void	slcd_init (uint64_t lcd_pins, slcd_bias_value_t bias, slcd_duty_value_t duty, slcd_clocksource_value_t clocksource, slcd_prescaler_value_t prescaler, slcd_clockdiv_value_t clkdiv)
	Initializes the SLCD peripheral, but does not enable it.
void	slcd_set_contrast (uint8_t contrast)
	Sets the contrast level for the display. Valid values are from 0-15.
void	slcd_enable (void)
	Enables the SLCD peripheral.
bool	slcd_is_enabled (void)
	Checks if the SLCD peripheral is currently enabled.
void	slcd_clear (void)
	Clears all display memory.
void	slcd_set_segment (uint8_t com, uint8_t seg)
	Sets a segment in the display memory.
void	slcd_clear_segment (uint8_t com, uint8_t seg)
	Clears a segment in the display memory.
void	slcd_configure_frame_counter (uint8_t fc, uint8_t overflow_count, bool prescale)
	Configures one of the three frame counters.
void	slcd_set_frame_counter_enabled (uint8_t fc, bool enabled)
	Enables or disables one of the three frame counters.
void	slcd_set_frame_counter_interrupt_enabled (uint8_t fc, bool enabled)
	Enables or disables one of the three frame counter interrupts.
void	slcd_configure_blink (bool blink_all, uint8_t bss0, uint8_t bss1, uint8_t fc)
	Configures the blink mode, but does not start blinking.
void	slcd_set_blink_enabled (bool enabled)
	Enables or disables blinking according to the configuration set by slcd_configure_blink.
void	slcd_configure_circular_shift_animation (uint16_t initial_value, uint8_t size, slcd_csrshift_value_t shift_dir, uint8_t fc)
	Configures the Circular Shift Register animation, but does not start it. This is pretty obscure and you should consult the datasheet for more information.
void	slcd_set_circular_shift_animation_enabled (bool enabled)
	Enables or disables circular shift register animation according to the configuration set by slcd_configure_circular_shift_animation.
void	slcd_disable (void)
	Disables the SLCD peripheral.

Detailed Description

Functions for configuring and using the SAM L22's Segment LCD peripheral.

Function Documentation

slcd_clear()

void slcd_clear

(

void

)

Clears all display memory.

TODO: Can we optimize this? If under 32 segments, we can write 0 to just the SDATAL registers. For only 3 or 4 COMs, we can skip higher numbered registers.

slcd_clear_segment()

void slcd_clear_segment	(	uint8_t	com,
		uint8_t	seg )

Clears a segment in the display memory.

Parameters

com	The common line to clear. Valid options are 0-7.
seg	The segment to clear. Valid options are 0-39.

slcd_configure_blink()

void slcd_configure_blink	(	bool	blink_all,
		uint8_t	bss0,
		uint8_t	bss1,
		uint8_t	fc )

Configures the blink mode, but does not start blinking.

Note

SLCD must be disabled to configure the blinking mode.

Parameters

blink_all	If true, all segments will blink. If false, only the segments specified in the next two masks will blink.
bss0	Blink segment select 0. A 1 in any bit position (n) will cause the (COMn, SEG0) segment to blink. Ignored if blink_all is true.
bss1	Blink segment select 1. A 1 in any bit position (n) will cause the (COMn, SEG1) segment to blink. Ignored if blink_all is true.
fc	The frame counter to use for blinking. Valid options are 0, 1, or 2.

slcd_configure_circular_shift_animation()

void slcd_configure_circular_shift_animation	(	uint16_t	initial_value,
		uint8_t	size,
		slcd_csrshift_value_t	shift_dir,
		uint8_t	fc )

Configures the Circular Shift Register animation, but does not start it. This is pretty obscure and you should consult the datasheet for more information.

Note

SLCD must be disabled to configure the circular shift register.

Parameters

initial_value	16 bits. The initial value of the circular shift register.
size	The size of the circular shift register. Valid options are 2 through 16.
shift_dir	The direction of the shift. Valid options are SLCD_CSRSHIFT_LEFT or SLCD_CSRSHIFT_RIGHT.
fc	The frame counter to use for shifting. Valid options are 0, 1, or 2.

slcd_configure_frame_counter()

void slcd_configure_frame_counter	(	uint8_t	fc,
		uint8_t	overflow_count,
		bool	prescale )

Configures one of the three frame counters.

Note

SLCD must be disabled to configure frame counters.

Parameters

fc	The frame counter to enable. Valid options are 0, 1, or 2.
overflow_count	The number of frames to count before the overflow fires. Maximum value is 32 frames.
prescale	If true, the frame counter will count every 8th frame instead of every frame. This will let you count up to 256 frames in increments of 8.

slcd_init()

void slcd_init	(	uint64_t	lcd_pins,
		slcd_bias_value_t	bias,
		slcd_duty_value_t	duty,
		slcd_clocksource_value_t	clocksource,
		slcd_prescaler_value_t	prescaler,
		slcd_clockdiv_value_t	clkdiv )

Initializes the SLCD peripheral, but does not enable it.

This function sets up the SLCD peripheral with some defaults:

• LCD runs in standby
• Lowest possible contrast level (2.45 volts)
• Uses the low power waveform
• Charge pump refresh at 250Hz (slowest option)
• Reference Refresh at 62.5Hz (slowest option)
• Bias buffer enabled (side note / TODO: does turning this off save power?)

You will need to specify the remaining configuration options. Duty and bias are easy, but prescaler, clock divider and number of COM lines will combine to determine the frame rate of the display according to this formula: 32768/(prescaler * clock_divider * number_of_common_lines)

Parameters

lcd_pins	A 64-bit mask of the pins to use for the SLCD, as numbered in the pin mux table in the data sheet (SLCD/LP[n]). For example, PB08 is SLCD/LP[2] and PA05 is SLCD/LP[5], so the mask for using both of these pins would be (1 << 2) | (1 << 5). The lowest pins are always used as the common lines, so for a 1/2 duty LCD using pins 2, 5, 6, 7, 30 and 35, pins 2 and 5 would be the COM0 and COM1, and the rest would be segment lines SEG0-SEG3.
bias	The bias configuration for the SLCD. Valid options are: SLCD_BIAS_STATIC for a static display (0V, VLCD) SLCD_BIAS_HALF for 1/2 bias (0V, 1/2 VLCD, VLCD) SLCD_BIAS_THIRD for 1/3 bias (0V, 1/3 VLCD, 2/3 VLCD, VLCD) SLCD_BIAS_FOURTH for 1/4 bias (0V, 1/4 VLCD, 1/2 VLCD, 3/4 VLCD, VLCD)
duty	The duty cycle for the SLCD, aka the number of common lines. Valid options are: SLCD_DUTY_1_COMMON for a static display SLCD_DUTY_2_COMMON for two common lines and a 1/2 duty cycle SLCD_DUTY_3_COMMON for three common lines and a 1/3 duty cycle SLCD_DUTY_4_COMMON for four common lines and a 1/4 duty cycle SLCD_DUTY_6_COMMON for six common lines and a 1/6 duty cycle SLCD_DUTY_8_COMMON for eight common lines and a 1/8 duty cycle
clocksource	The clock source for the SLCD. Valid options are: SLCD_CLOCKSOURCE_ULP for the low-accuracy, low-power internal 32kHz oscillator SLCD_CLOCKSOURCE_XOSC for an external 32kHz crystal oscillator
prescaler	The prescaler factor, which initially divides the 32kHz clock. Valid options are: SLCD_CTRLA_PRESC_PRESC16_Val - Divide by 16 SLCD_CTRLA_PRESC_PRESC32_Val - Divide by 32 SLCD_CTRLA_PRESC_PRESC64_Val - Divide by 64 SLCD_CTRLA_PRESC_PRESC128_Val - Divide by 128
clock_divider	The clock divider, which divides the prescaled clock. Valid options areL SLCD_CLOCKDIV_1 for no division SLCD_CLOCKDIV_2 to divide by 2 SLCD_CLOCKDIV_3 to divide by 3 SLCD_CLOCKDIV_4 to divide by 4 SLCD_CLOCKDIV_5 to divide by 5 SLCD_CLOCKDIV_6 to divide by 6 SLCD_CLOCKDIV_7 to divide by 7 SLCD_CLOCKDIV_8 to divide by 8

slcd_is_enabled()

bool slcd_is_enabled

(

void

)

Checks if the SLCD peripheral is currently enabled.

Returns

true if the SLCD peripheral is enabled, false if it is not.

slcd_set_blink_enabled()

void slcd_set_blink_enabled

(

bool

enabled

)

Enables or disables blinking according to the configuration set by slcd_configure_blink.

Note

You can enable blinking at any time; there is no need to disable the SLCD first.

Parameters

enabled

If true, blinking is enabled. If false, blinking is disabled.

slcd_set_circular_shift_animation_enabled()

void slcd_set_circular_shift_animation_enabled

(

bool

enabled

)

Enables or disables circular shift register animation according to the configuration set by slcd_configure_circular_shift_animation.

Note

You can enable the CSR animation at any time; there is no need to disable the SLCD first.

Parameters

enabled

If true, the CSR animation is enabled. If false, the CSR animation is disabled.

slcd_set_contrast()

void slcd_set_contrast

(

uint8_t

contrast

)

Sets the contrast level for the display. Valid values are from 0-15.

Parameters

contrast

The contrast configuration for the SLCD

In internal supply mode, VLCD is in the range of 2.45V (contrast 0) to 3.45V (contrast 15).

Note

You can set the contrast level at any time, without disabling the SLCD.

slcd_set_frame_counter_enabled()

void slcd_set_frame_counter_enabled	(	uint8_t	fc,
		bool	enabled )

Enables or disables one of the three frame counters.

Note

You can enable a frame counter at any time; there is no need to disable the SLCD first.

Parameters

fc	The frame counter to enable. Valid options are 0, 1, or 2.
enabled	If true, the frame counter is enabled. If false, the frame counter is disabled.

slcd_set_frame_counter_interrupt_enabled()

void slcd_set_frame_counter_interrupt_enabled	(	uint8_t	fc,
		bool	enabled )

Enables or disables one of the three frame counter interrupts.

Parameters

fc	The frame counter whose interrupt you want to configure. Valid options are 0, 1, or 2.
enabled	If true, the frame counter interrupt is enabled. If false, the interrupt is disabled.

Note

This function assumes you only use one frame counter as an interrupt source. When you disable the frame counter interrupt, it disables all SLCD interrupts.

slcd_set_segment()

void slcd_set_segment	(	uint8_t	com,
		uint8_t	seg )

Sets a segment in the display memory.

Parameters

com	The common line to set. Valid options are 0-7.
seg	The segment to set. Valid options are 0-39.