Arduino library containing all the LED specific code needed for the various DCC decoders. Although this library is part of the DCC decoder core Library, it can also be used seperately.
There are already several LED related libraries for model trains, of which the best known are MobaTools (https://github.com/MicroBahner/MobaTools) and the MobaLedLib (https://github.com/Hardi-St/MobaLedLib). This library supports flashing, fade-out and some specific methods that are shared between all my decoders.
To accommodate specific needs and to save valuable RAM space, four different classes have been defined (between brackets how much RAM is needed per object instantiation):
- BasicLed (2 bytes)
- FlashLed (11 bytes)
- DccLed (11 bytes)
- FadeOutLed (23 bytes)
Technically, the FlashLed inherits methods and attributes from the BasicLed, the DccLed inherits from the FlashLed and the FadeOutLed again inherits from the BasicLed. This means that each class can use all BasicLed methods, and the DccLed can also use the methods and (public) attributes from the FlashLed.
The BasicLed class is intended for simple LED actions, such as turning the LED on, off or to toggle its state.
To connect the processor output pin to the LED. In many cases the output pin for the onboard LED is LED_BUILTIN.
Although most boards are designed to switch the LED ON once the output pin gets HIGH, there are also some boards where the logic is inverted and the LED switches ON once the output pin gets LOW. In such cases the optional parameter invert may be used to change the output logic. If invert is not specified, the default behaviour is not-inverted.
Returns true if the LED is ON. Can also be used in case of inverted logic.
To turn the LED on.
To turn the LED off.
If the LED is on, it will be turned off. If the LED is off, it will be turned on.
The FlashLed class allows the flashing of LEDs. The class inherits methods and attributes from the BasicLed class, so all the methods described above can be used again. In addition, the following methods and attributes exist.
All Flash attributes or of the uint8_t type, which means that the possible values range from 0..255. All times are specified in 100ms steps, which means that the highest value is 25,5 seconds.
- uint8_t flashOntime
Time the LED should be ON (in 100ms steps) - uint8_t flashOfftime
Time the LED should be OFF (in 100ms steps) - uint8_t flashPause
Time in between a series of flashes in which the LED should remain off (in 100ms steps) - uint8_t flashCount
Number of flashes before a pause - bool neverStopFlashing
A boolean to indicate if we want a single series of flashes, or that we start again after aflashPausewith a new series of pulses.
Same as BasicLed attach(), but performs some additional initialisation actions.
Puts the LED in flashing mode, based on the settings of attributes as shown above.
Creates a continuous series of slow flashes. flashOntime, flashOfftime as well as flashPause are all 500ms. The associated attributes are automatically set, and not need be specified again.
Creates a continuous series of fast flashes. flashOntime is 100ms, and flashOfftime as well as flashPause are both 200ms.
Should be called from main as often as possible. Update will check every 100ms if it is time to turn the LED on or off.
The idea of the DccLed class is to define some common methods that can be used (and are therefore the same) for each decoder.
The DccLed class inherits methods and attributes from the FlashLed class, so all the methods described there can be used again. In addition, the following methods exist.
To indicate that the decoder (has re)started. Two short flashes of 200ms each.
Single very short flash (200ms), to indicate an activity, such as a switch command.
Single short flash (500ms), to indicate that an (RS-Bus) feedback message is send.
The FadeOutLed class was defined to allow LEDs to slowly fade out, without using the hardware PWM functions that many boards offer. Development was needed for a board with a Mega2560 processor, which connected a large number of LEDs that could not be attached to pins that supported with hardware PWM. Since the FadeOutLed class is relatively expensive in both RAM and CPU usage, in many cases it might be better to use other libraries that support hardware based FadeOut (and FadeIn).
All Fade attributes or of the uint8_t type, which means that the possible values range from 0..255. All times are specified in 100ms steps, which means that the the longest time to fade out is 25,5 seconds. The default values may be fine for most cases.
- uint8_t fadeTime
The time it takes to change the brightness from 100% to 0% (in 100ms steps). The default value is 4 seconds. - uint8_t fadeSteps
Number of steps between the LED brightness moves from 100% to 0%. Higher values give smoother behaviour, but increase CPU load. The default is 50 steps. - uint8_t pwmFrequency
The brightness of the LED is set by using a (software generated) PWM (Pulse Width Modulation) signal. The default frequency is 50Hz, which is high enough for the human eye. Higher values increase CPU load.
Same as BasicLed attach(), but performs some additional initialisation actions.
Starts fading the LED, using the values as specified above.
Should be called from main as often as possible. Update will check every 100ms if it is time to change the LED intensity.
#include <Arduino.h>
#include <AP_DccLED.h>
BasicLed myLed; // Instantiate the LED object
const uint8_t ledPin = LED_BUILTIN; // Can be used for most boards (13)
void setup() {
myLed.attach(ledPin);
}
void loop() {
myLed.turn_on();
delay(500);
myLed.turn_off();
delay(1500);
}
#include <Arduino.h>
#include <AP_DccLED.h>
FlashLed myLed; // Instantiate the LED object
const uint8_t ledPin = LED_BUILTIN; // Can be used for most boards (13)
void setup() {
myLed.attach(ledPin);
myLed.flashOntime = 2; // 200ms (all times are in 100ms steps)
myLed.flashOfftime = 5; // 500ms
myLed.flashCount = 5;
myLed.flashPause = 20; // 2 seconds
myLed.neverStopFlashing = true;
myLed.flash();
}
void loop() {
myLed.update();
}