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author | Marti Bolivar <mbolivar@mit.edu> | 2010-10-20 06:46:52 -0400 |
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committer | Marti Bolivar <mbolivar@mit.edu> | 2010-10-20 06:46:52 -0400 |
commit | 85c1c72db022bba891868afd3375e39dbe245701 (patch) | |
tree | 9d86a3db825667362a8c89a98a205586015aec94 /source/arduino/digitalwrite.rst | |
parent | abcfcc62cc62dfc088d30d5a6b6c36d6c89f7b07 (diff) | |
download | librambutan-85c1c72db022bba891868afd3375e39dbe245701.tar.gz librambutan-85c1c72db022bba891868afd3375e39dbe245701.zip |
initial check-in of arduino docs in RST format (converted using wget+pandoc)
Diffstat (limited to 'source/arduino/digitalwrite.rst')
-rw-r--r-- | source/arduino/digitalwrite.rst | 113 |
1 files changed, 113 insertions, 0 deletions
diff --git a/source/arduino/digitalwrite.rst b/source/arduino/digitalwrite.rst new file mode 100644 index 0000000..82e1813 --- /dev/null +++ b/source/arduino/digitalwrite.rst @@ -0,0 +1,113 @@ +.. _arduino-digitalwrite: + +digitalWrite() +============== + +Description +----------- + +Write a `HIGH <http://arduino.cc/en/Reference/Constants>`_ or a +`LOW <http://arduino.cc/en/Reference/Constants>`_ value to a +digital pin. + + + +If the pin has been configured as an OUTPUT with +`pinMode <http://arduino.cc/en/Reference/PinMode>`_\ (), its voltage +will be set to the corresponding value: 5V (or 3.3V on 3.3V boards) +for HIGH, 0V (ground) for LOW. + + + +If the pin is configured as an INPUT, writing a HIGH value with +digitalWrite() will enable an internal 20K pullup resistor (see the +`tutorial on digital pins <http://arduino.cc/en/Tutorial/DigitalPins>`_). +Writing LOW will disable the pullup. The pullup resistor is enough +to light an LED dimly, so if LEDs appear to work, but very dimly, +this is a likely cause. The remedy is to set the pin to an output +with the pinMode() function. + + + +**NOTE:** Digital pin 13 is harder to use as a digital input than +the other digital pins because it has an LED and resistor attached +to it that's soldered to the board on most boards. If you enable +its internal 20k pull-up resistor, it will hang at around 1.7 V +instead of the expected 5V because the onboard LED and series +resistor pull the voltage level down, meaning it always returns +LOW. If you must use pin 13 as a digital input, use an external +pull down resistor. + + + +Syntax +------ + +digitalWrite(pin, value) + + + +Parameters +---------- + +pin: the pin number + + + +value: `HIGH <http://arduino.cc/en/Reference/Constants>`_ or +`LOW <http://arduino.cc/en/Reference/Constants>`_ + + + +Returns +------- + +none + + + +Example +------- + +:: + + + int ledPin = 13; // LED connected to digital pin 13 + + void setup() + { + pinMode(ledPin, OUTPUT); // sets the digital pin as output + } + + void loop() + { + digitalWrite(ledPin, HIGH); // sets the LED on + delay(1000); // waits for a second + digitalWrite(ledPin, LOW); // sets the LED off + delay(1000); // waits for a second + } + + + +Sets pin 13 to HIGH, makes a one-second-long delay, and sets the +pin back to LOW. + + + +Note +---- + +The analog input pins can be used as digital pins, referred to as +A0, A1, etc. + + + +See also +-------- + + +- `pinMode <http://arduino.cc/en/Reference/PinMode>`_\ () +- `digitalRead <http://arduino.cc/en/Reference/DigitalRead>`_\ () +- `Tutorial: Digital Pins <http://arduino.cc/en/Tutorial/DigitalPins>`_ + + |