LCD

These functions allow for graphics on multiple display types, including B&W and color display.

B&W Displays

LCD Graphics supports SSD1306 128x64 B&W I2C, which work on all BrainPad boards. This display is found on the BrainPad Pulse by default, and can be added to the I2C channel on all of the other boards. These displays are available in multiple sizes but most common is 0.96". The LcdConfig() function (documented below) can be used to configure the system to work with an externally connected display.

SSD1306

Tip

We have tested 2.42" displays that use SSD1309 and seemed to work perfectly.

SSD1309

Caution

Displays with knock-off controller SSH1106 that is supposed to be compatible with SSD1306 did not work as expected.

Color Displays

ColorDisplays

Support for color displays includes ILI9342, ILI9341, and ST7735. These color displays only work on boards with SC13 chipset. The LcdConfig() function (documented below) can be used to configure the system to work with an externally connected display.

Display Configuration

LcdConfig(address, config, cs, dc) Configures a connected display.
address: Display's address or type. 0 = on-board display.
config: external LCD configuration.
cs: Chip select pin.
dc: Data control pin.

Tip

This function is not needed to use the on-board display.

address: For I2C displays: This is the 7-bit I2C device's address of the connected SSD1306 display. All other arguments are ignored. For SPI displays: This is the SPI display's type 0x08: ILI9342, 0x81: ILI9341, 0x82: ST7735.

config: these values can be added together to make up the desired configuration.

value (bits)	Function	Value
1 (bit0)	Orientation	0: Landscape, 1: Portrait
2 (bit1)	Flip Horizontal	0: None, 1: Flip
4 (bit2)	Flip Vertical	0: None, 1: Flip
8 (bit3)	RGB	0: None, 1: BGR
16 (bit4)	Swap Byte Endianness	0: None, 1: Swap
32 (bit5)	Reserved
64 (bit6)	Reserved
128 (bit7)	Reserved
bits[8..11]	Window x	Special config
bits[12..15]	Window y	Special config

cs: The pin connected to the display's Chip select signal.

dc: The pin connected to the display's Data Control signal.

This example will set the system to use the color display adapter from Waveshare, which uses ST7735 1.8" display. The display's chip select is on pin 16 and data control is on pin 12. There is also a backlight on pin 1 and reset on pin 8 that need to be controlled manually.

The display on adapter needs to be flipped horizontally (config value 2) and also requires this value added, 0x2100. This sets the drawing window.

ST7735

DWrite(1,1)#turn on the back-light
DWrite(8,1)# release reset 

LcdConfig (0x82,2+0x2100,16,12)
LcdClear(0)
LcdTextS("DUE has Color",0x00FF00,0,0,2,3)

for c in range(2,200)
    LcdLine(c,c,40,c,60)
    LcdLine(c<<8,200-c,60,200-c,80)
    LcdLine(c<<16,c,80,c,100)
next

LCDShow()

To set the display to portrait mode, change the config line to LcdConfig (0x82, 1+0x2100, 16, 12). Flip is not needed in this case.

ST7735

This example below will direct graphics to an external 2.42" display with address 0x3C, wired to the 2.42" SSD1309 display showing in the image above. Tip: A resistor on the back of the display needs to be moved to change its bus from SPI to I2C.

LcdConfig(0x3C,0,0,0)
LcdClear(0)
LcdText("Hello World",1,10,10)
LcdShow()

Graphical Memory

All LCD functions process the graphics commands in an internal memory. It starts with LcdClear(), which clears up the entire graphics memory to a specific color. When the user is ready, the graphical memory is transferred to the display using LcdShow().

LcdShow() Sends the display buffer to the LCD.
LcdClear(color) Clears the entire screen to black or white
color: Color value

LcdClear(0)
LcdShow()

Color Value

The system supports Color and B&W displays. To keep uniformity, 0 is always black and 1 is always white. Any other value is considered a standard RGB color formatted 0xRRGGBB. For example, GHI Electronics blue is 0x0977aa.

Draw Line

LcdLine(color, x1,y1,x2,y2)
color: Color value
x1: Starting x point
y1: Starting y point
x2: Ending x point
y2: Ending y point

LcdClear(0)
LcdLine(1,0,0,128,64)
LcdShow()

Set Pixel

LcdPixel(color, x, y)
color: Color value
x: x pixel value
y: y pixel value

LcdClear(0)
LcdPixel(1,64,32)
LcdShow()

Draw Circle

LcdCircle(color, x,y,radius)
color: Color value
x: x position of circle's center
y: y position of circle's center
radius: radius of the circle

LcdClear(0)
LcdCircle(1,64,32,31)
LcdShow()

Draw Rectangle

LcdRect(color, x, y, width, height)
color: Color value
x: Starting x point
y: Starting y point
width: Rectangle width
height: Rectangle height

LcdClear(0)
LcdRect(1,10,10,118,54)
LcdShow()

Draw Filled Rectangle

LcdFill(color, x, y, width, height)
color: Color value
x: Starting x point
y: Starting y point
width: Rectangle width
height: Rectangle height

LcdClear(0)
LcdFill(1,10,10,118,54)
LcdShow()

Draw Text

LcdText("text", color, x, y)
text: String message in double quotes.
Str(): is used to convert variables to strings
color: Color value
x: x position
y: x position

LcdClear(0)
LcdText("Hello World",1,10,10)
LcdShow()
x=100
LcdClear(0)
LcdText(Str(x),1,0,0)
LcdShow

Draw Tiny Text

Displays tiny 5px text.

LcdTextT("text", color, x, y)
text: String message in double quotes.
Str(): is used to convert variables to strings
color: Color value
x: x position
y: x position

Draw Scaled Text

Works exactly the same as LcdText() but adds scaling.

LcdTextS("text", color, x, y, scaleWidth, scaleHeight)
text: String message in double quotes.
Str(): is used to convert variables to strings
color: Color value
x: x position
y: x position
scaleWidth: Width scale multiplier
scaleHeight: Height scale multiplier

LcdClear(0)
LcdTextS("Hello",1,0,0,2,2)
LcdShow()
Wait(1000)
x=100
LcdClear(0)
LcdTextS(Str(x),1,0,0,2,2)
LcdShow()

Tip

Scale is multiplier for the pixel in width and height to make the font larger ()

Draw Image

LcdImg(array, x, y, transform)
array: Image array (see below).
x: x position on screen.
y: y position on screen.
transform: transform modifier.

There are cases where images need to be added to the screen. Of course, we are taking about basic simple images, more like a tiny sprite in a game.

The image is an array of pixels. This arrays must start with 2 elements that contain the image's width and height. We will place the array on multi line to help us visualize what the image might look like, but placing everything on a single line has the same effect

Image Array formatting:

Dim a[2+(8*8)] = [8,8,
0, 0, 0, 1, 1, 0, 0, 0,
0, 0, 1, 1, 1, 1, 0, 0,
0, 1, 1, 1, 1, 1, 1, 0,
1, 1, 0, 1, 1, 0, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1,
0, 0, 1, 0, 0, 1, 0, 0,
0, 1, 0, 1, 1, 0, 1, 0,
1, 0, 1, 0, 0, 1, 0, 1]

The following example displays the image array on the screen.

Dim a[2+(8*8)] = [8,8,
0, 0, 0, 1, 1, 0, 0, 0,
0, 0, 1, 1, 1, 1, 0, 0,
0, 1, 1, 1, 1, 1, 1, 0,
1, 1, 0, 1, 1, 0, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1,
0, 0, 1, 0, 0, 1, 0, 0,
0, 1, 0, 1, 1, 0, 1, 0,
1, 0, 1, 0, 0, 1, 0, 1]
LcdClear(0)
LcdImg(a,60,30,0)
LcdShow()

Transformation modifiers:

Value	Transformation
0	No transform
1	Flip image horizontally
2	Flip image vertically
3	Rotate image 90 degrees
4	Rotate image 180 degrees
5	Rotate the image 270 degrees(same as -90 degrees)

Draw Scaled Image

Works the same as LcdImg() but adds scaling.

LcdImgS(array, x, y, scaleWidth, scaleHeight, transform)
array: Image array (see below).
x: x position on screen.
y: y position on screen.
scaleWidth: Width scale multiplier
scaleHeight: Height scale multiplier
transform: transform modifier. (see above)

LCD Stream

Stream is used to send the entire LCD update.

Note

Streams are not coded directly using DUE Script, see Streams

LcdStream(colorDepth)
ColorDepth: This lets the stream know what is the format of the incoming data stream. B&W displays only support 1. Color displays support 4 (palette), 8, and 16 bits.

The command is followed by the data stream. The stream size is determined by the used screen size and the color depth. For example, Pulse uses a 128x64 display with 1bpp. This results in 128x64/8 = 1KBytes.

Tip

On 1bpp display, the data is organized as 8bit columns going left to right and then wrapping around to the next row.

Palette

Palette(index, colorValue) - Sets the desired color for a palette.
index: Index number of color
colorValue: A standard HEX value of the RGB color.

The palette is used when 4bpp color depth is used with streams. The palette table is used as a lookup table to set the color for each one of the 16 possibilities. The default colors are below; however, the user can change it to whatever they desire. For example, they can be set to 16 shades of green to show a forest scene that needs different shades of green.

Default colors:

Index	Color Value	Color
0	0x000000	Black
1	0xFFFFFF	White
2	0xFF0000	Red
3	0x32CD32	Lime
4	0x0000FF	Blue
5	0xFFFF00	Yellow
6	0x00FFFF	Cyan
7	0xFF00FF	Magenta
8	0xC0C0C0	Silver
9	0x808080	Gray
10	0x800000	Maroon
11	0xBAB86C	Olive
12	0x00FF00	Green
13	0xA020F0	Purple
14	0x008080	Teal
15	0x000080	Navy

Example code to set a pixel at 10x10

int x=10;
int y=10;

buffer[(y >> 3) * 128 + x] |= (byte)(1 << (y & 7));

Note

LCD Stream automatically calls LcdShow() internally.