# LED screen

The BBC micro:bit LED screen consists of 25 red LED lights arranged in a 5X5 grid (5 LEDs across by 5 LEDs down).

# Which LED?

You use `x , y` coordinates to specify a particular LED in the grid; where `x` is the horizontal position and `y` is the vertical position (0, 1, 2, 3, 4). To figure out the `x`, `y` coordinates, position your micro:bit horizontally, like a credit card (see picture above).

Here are the x, y coordinates for the LEDs in the 5X5 grid:

`0, 0` `1, 0` `2, 0` `3, 0` `4, 0`

`0, 1` `1, 1` `2, 1` `3, 1` `4, 1`

`0, 2` `1, 2` `2, 2` `3, 2` `4, 2`

`0, 3` `1, 3` `2, 3` `3, 3` `4, 3`

`0, 4` `1, 4` `2, 4` `3, 4` `4, 4`

The x, y coordinates for the LED in the centre of the grid are `2, 2`. Starting from `0, 0` count over 2 columns and then down 2 rows.

### Row, column - 1

Since the row and column numbers start at 0, an easy way to figure out the x, y coordinates is to subtract 1 from the row and column number (when counting from 1). In other words, to specify the LED in the 4th column 5th row, subtract 1 from each number to get coordinates `3, 4`.

# Coding the LEDs

## MakeCode Editor

### Turning a LED on/off

Use plot and unplot to turn an LED on or off.

### Is a LED on/off?

Use the point function to find out if a LED is on or off.

### Display images, strings and numbers

Instead of turning individual LEDs on or off, as above, you can display an image directly to the screen or show text/numbers on screen using the show number/show string function.

## Python

See the images section of the documentation to learn more about programming the LEDs in Python for micro:bit.