2.59 Breathing/Blinking LED
LEDs are used in computer applications to communicate internal state information to a user through a minimal interface.
Typical applications will cause an LED to blink at different rates to convey different state information. For example, an LED could be full on, full off, blinking at a rate of once a second, or blinking at a rate of once every four seconds, in order to communicate four different states.
As an alternative to blinking, an LED can “breathe”, that is, oscillate between a bright state and a dim state in a continuous, or apparently continuous manner. The rate of breathing, or the level of brightness at the extremes of the oscillation period, can be used to convey state information to the user that may be more informative, or at least more novel, than traditional blinking.
Using the Library
The LEDx_Initialize routine will set up the LED for the breathing action as configured using MCC. No additional APIs are typically needed to be called to achieve the breathing action.
Library Interface
LED peripheral library provides the following interfaces:
Functions
| Name | Description |
|---|---|
| LEDx_Initialize | Initializes given instance of LED peripheral. |
| LEDx_ClockPrescalerSet | Configures the prescaler for the PWM clock in LED blinking mode |
| LEDx_DutyCycleCountSet | Configures the duty cycle of the blink function in LED blinking mode |
| LEDx_DutyCycleMaxSet | Specifies the maximum duty cycle value. |
| LEDx_DutyCycleMinSet | Specifies the minimum duty cycle value. |
| LEDx_HighDelaySet | Specifies the number of PWM periods to wait before updating the current duty cycle when the current duty cycle is greater than or equal to the value MAX in register LED_LIMIT |
| LEDx_LowDelaySet | Specifies the number of PWM periods to wait before updating the current duty cycle when the current duty cycle is greater than or equal to the value MIN in register LED_LIMIT |
| LEDx_SegmentsIntervalSet | Configures the number of PWM periods between updates to current duty cycle |
| LEDx_SegmentsStepSizeSet | Configures the amount the current duty cycle is adjusted at the end of every PWM period |
| LEDx_SymmetrySet | Configures the LED rising and falling times in Asymmetric or Symmetric modes |
| LEDx_Update | Enables update of LED Delay, LED Step and LED interval registers |
| LEDx_WDT_CallbackRegister | Allows application to register a callback with the LED WDT module |
| LEDx_WDTReloadCountSet | Configures the PWM WDT counter value |
Data types and constants
| Name | Type | Description |
|---|---|---|
| LED_WDT_CALLBACK | Typedef | Defines the data type and function signature for the LED WDT callback function. |
| LED_SYM | Enum | Defines the enumerations associated with LED symmetry modes |