918af4f3ac
* change simulator svg * change radio image * Remove google fonts cdn * change color of 'advanced' button * font fix * font fix 2 * display fix * change fullsceen simulator bg * Continuous servo * handle continuous state * adding shims * update rendering for continuous servos * fixing sim * fix sig * typo * fix sim * bump pxt * bump pxt * rerun travis * Input blocks revision - add Button and Pin event types - merge onPinPressed & onPinReleased in new onPinEvent function - create new onButtonEvent function * update input blocks in docs and tests * remove device_pin_release block * Hide DAL.x behind Enum * bring back deprecated blocks, but hide them * shims and locales files * fix input.input. typing * remove buildpr * bump V3 * update simulator aspect ratio * add Loudness Block * revoke loudness block * Adds soundLevel To be replaced by pxt-common-packages when DAL is updated. * Remove P0 & P3 from AnalogPin Co-authored-by: Juri <gitkraken@juriwolf.de>
98 lines
3.2 KiB
Markdown
98 lines
3.2 KiB
Markdown
# LED screen
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```sim
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basic.showLeds(`
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# . # . #
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. # . # .
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# . # . #
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. # . # .
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# . # . #
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`);
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```
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The micro:bit LED screen has 25 red LED lights arranged in a 5X5 grid (5 LEDs across by 5 LEDs down).
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In the screen above, we created a checkerboard pattern using the LEDs.
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## Which LED?
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You use `(x ,y)` coordinates to specify a particular LED in the grid;
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where `x` is the horizontal position (0,1,2,3,4) and `y` is the vertical position
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(0, 1, 2, 3, 4).
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To figure out the ``x``, ``y`` coordinates, position your micro:bit horizontally, like a credit card (see picture above).
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Here are the x, y coordinates for the LEDs in the 5X5 grid:
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`(0,0)` `(1,0)` `(2,0)` `(3,0)` `(4,0)`
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`(0,1)` `(1,1)` `(2,1)` `(3,1)` `(4,1)`
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`(0,2)` `(1,2)` `(2,2)` `(3,2)` `(4,2)`
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`(0,3)` `(1,3)` `(2,3)` `(3,3)` `(4,3)`
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`(0,4)` `(1,4)` `(2,4)` `(3,4)` `(4,4)`
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The x, y coordinates for the LED in the center of the grid are `(2,2)`. Starting from `(0,0)` count over 2 columns and then down 2 rows.
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## Check your understanding
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Which LEDs are turned on in the checkboard pattern above?
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## Row, column - 1
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Since the row and column numbers start at 0, an easy way to figure out the (x,y) coordinates
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is to subtract 1 from the row and column number (when counting from 1).
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In other words, to specify the LED in the 4th column 5th row, subtract 1 from each number to get coordinates `(3,4)`.
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## Turn a LED on/off
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Use [plot](/reference/led/plot) and [unplot](/reference/led/unplot) to turn a LED on or off
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```blocks
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led.plot(0,0);
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led.plot(1,1);
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basic.pause(1000);
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led.unplot(0,0);
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basic.pause(1000);
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led.unplot(1,1);
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```
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## Is a LED on/off?
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Use the [point](/reference/led/point) function to find out if a LED is on or off.
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```blocks
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if(led.point(0,0)) {
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}
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```
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## Display images, strings and numbers
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Instead of turning individual LEDs on or off, as above, you can display an [image](/reference/images/image) directly to the screen or show text and numbers on screen using the [show number](/reference/basic/show-number) and [show string](/reference/basic/show-string) functions.
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## The display buffer
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The micro:bit runtime keeps a representation of the state of all 25 LEDS in memory. This state is known as the "display buffer" and controls which LEDs are on and which are off. The plot, unplot, and point functions access the display buffer directly. On the other hand, the functions that show an image, number, or string overwrite the buffer completely. To illustrate this, first try running this code sequence
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```blocks
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basic.showString("d")
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led.plot(0, 0)
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```
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You will see the letter "d" displayed as well as the LED in position `0,0` lit up. Now try reversing the order of the two statements above:
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```blocks
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led.plot(0, 0)
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basic.showString("d")
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```
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You will not see the LED at position `0,0` lit up because the `show string` function overwrites the whole display buffer.
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## Pins: P3, P4, P6, P7, P9, P10
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These pins are coupled to the LED matrix display and also to the display's associated ambient light sensing mode.
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To disable the display driver feature (which will automatically disable the light sensing feature) use the function [led.enable](/reference/led/enable).
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More information at http://tech.microbit.org/hardware/edgeconnector_ds/ .
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