be7858cbed
* Fix example and do a few edits (#850) * Small fixes to the Karel project text (#862) * fix missing shadow type * add calibration info (#897) microbit-support:6348 User reported bug, but didn't realie micro:bit compass had to be calibrated on first run of the program. * Cherry pick adding various cross-editor compat APIs (#863) * fix nudge * Fix a typo ("screent") in the documentation (#1012) * Fix a typo "screent" -> "the LED screen" * Update showArrow doc string for consistency with other methods * Doc bugs found by xlators (#899) * Update rotation.md (#998) reflects actual behaviour of the board * fixed layout corruption (#1073) * Updating the new bug filer with the right link * Update challenges.md (#1325) For what I'm taught in school, 2 follows 1 😉😉. * Update simulator.md (#1209) * Update plant watering.md (#1264) the connection to servo are male not female * support for MIDI simulator in v0 (#1331) * Doc improvements (#1337) * update grammar in radio-dashboard sample code * Chanllenge 2 follows 1 I open all challenges.md without "Challenge 2" and review the file `grep -r "Challenge 2" -L | grep challenge | xargs -I@ code @` Changes to be committed: modified: docs/lessons/counter/challenges.md modified: docs/lessons/game-counter/challenges.md modified: docs/lessons/night-light/challenges.md modified: docs/lessons/snowflake-fall/challenges.md * Revert "support for MIDI simulator in v0 (#1331)" This reverts commit 30a9c411fb80762656e7a636feff8e77b7fd9e67. * Revert "Cherry pick adding various cross-editor compat APIs (#863)" This reverts commit 7308dbef23e9ee402bebb7e721d7014d8252c9e5. * Fixed pin needed to replace button A (#1385) * Cherry pick part of the signature update in in2cWriteBuffer (#863): 7308dbe
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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