Unit HyperPixel

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Description

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Pimoroni HyperPixel TFT Display Driver unit

The HyperPixel is a TFT display produced by Pimoroni for use with the Raspberry Pi. It uses the DPI (Display Parallel Interface) which is directly supported by the VideoCore GPU and means that unlike other TFT displays using SPI or similar interfaces it supports hardware accelerated graphics in the same way as HDMI or DSI displays.

The HyperPixel is available in several versions including a 4.0 inch rectangular, a 4.0 inch square and 2.1 inch round. Each version requires a slightly different set of instructions to initialize it and this unit provides the correct sequence for each of these displays.

To use this unit simply include it in your application and then call the function HyperPixelInitialize() as early as possible passing the appropriate model as the only parameter to the function. Once initialized successfully the HyperPixel display will be available via the standard framebuffer functions and also via the VC4 accelerated graphics options such as OpenVG, OpenGLES, OpenMAX and MMAL.

It is important to remember that no other devices should be enabled while using the HyperPixel display as it consumes almost all of the available GPIO pins. So it is not possible to use UART, I2C, SPI, PWM etc when the HyperPixel is installed.

The touch screen controller varies between models and this unit creates and initializes the appropriate one for the model selected. All touch screen devices are I2C based however as it is not possible to utilize the hardware I2C controller (see note above) a software I2C host is created to provide access to the touch screen.

The touch events generated from the device can be read from the normal touch or mouse API functions in much the same way as any other touch or mouse device.

In order to enable the HyperPixel display you need to add the appropriate settings to your config.txt file as follows:

For HyperPixel 4.0 Rectangular (800 x 480)

enable_dpi_lcd=1
dpi_group=2
dpi_mode=87
dpi_output_format=0x7f216
dpi_timings=480 0 10 16 59 800 0 15 113 15 0 0 0 60 0 32000000 6

For HyperPixel 4.0 Square (720 x 720)

enable_dpi_lcd=1
dpi_group=2
dpi_mode=87
dpi_output_format=0x7f226
dpi_timings=720 0 15 15 15 720 0 10 10 10 0 0 0 60 0 35113500 6

For HyperPixel 4.0 Square (2021 or later) (720 x 720)

enable_dpi_lcd=1
dpi_group=2
dpi_mode=87
dpi_output_format=0x5f026
dpi_timings=720 0 20 20 40 720 0 15 15 15 0 0 0 60 0 36720000 4

For HyperPixel 2.1 Round (480 x 480)

enable_dpi_lcd=1
dpi_group=2
dpi_mode=87
dpi_output_format=0x7f216
dpi_timings=480 0 10 16 55 480 0 15 60 15 0 0 0 60 0 19200000 6

The display can be rotated to the desired position by adding the display_lcd_rotate setting to the config.txt file as below, please see the official documentation at https://www.raspberrypi.com/documentation/computers/config_txt.html for more details.

No Rotation (Portrait)

display_lcd_rotate=0

Rotate 90 degrees clockwise (Landscape)

display_lcd_rotate=1

Rotate 180 degrees clockwise (Portrait)

display_lcd_rotate=2

Rotate 270 degrees clockwise (Landscape)

display_lcd_rotate=3

Horizontal flip

display_lcd_rotate=0x10000

Vertical flip

display_lcd_rotate=0x20000

To match the rotation of the touchscreen to the rotation of the display you must call the TouchDeviceControl() API function with the TOUCH_CONTROL_SET_ROTATION request and pass the appropriate touch rotation constant in argument1, eg TOUCH_ROTATION_180.

The touch device representing the touchscreen can be found by calling the API function TouchDeviceFindByDescription() and passing the appropriate description for your device.

For the HyperPixel 4.0 Rectangular the description will be "Goodix Touch Controller" and for the HyperPixel 4.0 Square and HyperPixel 2.1 Round the device can be located using the description "EDT FocalTech FT5x06 Touch Controller".

The touchscreen rotation values match with the display rotations as follows:

display_lcd_rotate=0 equals TOUCH_ROTATION_0
display_lcd_rotate=1 equals TOUCH_ROTATION_90
display_lcd_rotate=2 equals TOUCH_ROTATION_180
display_lcd_rotate=3 equals TOUCH_ROTATION_270

Constants

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HyperPixel model HYPERPIXEL*

HYPERPIXEL40_RECTANGLE = 0;
HYPERPIXEL40_SQUARE = 1;
HYPERPIXEL40_SQUARE2021 = 2;
HYPERPIXEL21_ROUND = 3;

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HyperPixel GPIO pins (All Models) HYPERPIXEL_GPIO_*

HYPERPIXEL_GPIO_PIN_FUNCTION = GPIO_FUNCTION_ALT2;
HYPERPIXEL_GPIO_PIN_PULL = GPIO_PULL_NONE;
HYPERPIXEL_GPIO_PIN_COUNT = 22;
HYPERPIXEL_GPIO_PINS:array[0..HYPERPIXEL_GPIO_PIN_COUNT - 1] of LongWord = (GPIO_PIN_0, GPIO_PIN_1, GPIO_PIN_2, GPIO_PIN_3, GPIO_PIN_4, GPIO_PIN_5, GPIO_PIN_6, GPIO_PIN_7, GPIO_PIN_8, GPIO_PIN_9, GPIO_PIN_12, GPIO_PIN_13, GPIO_PIN_14, GPIO_PIN_15, GPIO_PIN_16, GPIO_PIN_17, GPIO_PIN_20, GPIO_PIN_21, GPIO_PIN_22, GPIO_PIN_23, GPIO_PIN_24, GPIO_PIN_25);

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HyperPixel SPI pins (All Models) (Used during initialization) HYPERPIXEL_SPI_*

HYPERPIXEL_SPI_FUNCTION = GPIO_FUNCTION_OUT;
HYPERPIXEL_SPI_PULL = GPIO_PULL_NONE;
HYPERPIXEL_SPI_CLK = GPIO_PIN_27;
HYPERPIXEL_SPI_MOSI = GPIO_PIN_26;
HYPERPIXEL_SPI_CS = GPIO_PIN_18;
HYPERPIXEL_SPI_DELAY = 100;	Clock pulse time in microseconds
HYPERPIXEL_SPI_WAIT = 120;	Wait time in milliseconds before display on
HYPERPIXEL_SPI_CLK_ALT = GPIO_PIN_11;	CLK Pin (Round model)
HYPERPIXEL_SPI_MOSI_ALT = GPIO_PIN_10;	MOSI Pin (Round model)
HYPERPIXEL_SPI_DELAY_ALT = 10;	Clock pulse time in microseconds (Rectangle model)
HYPERPIXEL_SPI_WAIT_ALT = 200;	Wait time in milliseconds before display on (Rectangle model)

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HyperPixel touch I2C pins (All Models) (Used to create a software I2C device) HYPERPIXEL_I2C_*

HYPERPIXEL_I2C_SDA = GPIO_PIN_10;
HYPERPIXEL_I2C_SCL = GPIO_PIN_11;
HYPERPIXEL_I2C_DELAY = 4;

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HyperPixel backlight pins (All Models) (GPIO for backlight control) HYPERPIXEL_BACKLIGHT_*

HYPERPIXEL_BACKLIGHT_FUNCTION = GPIO_FUNCTION_OUT;
HYPERPIXEL_BACKLIGHT_PULL = GPIO_PULL_NONE;
HYPERPIXEL_BACKLIGHT_PIN = GPIO_PIN_19;

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HyperPixel touch interrupt pins (All Models) (GPIO for touch event registration) HYPERPIXEL_TOUCH_*

HYPERPIXEL_TOUCH_INTERRUPT_TRIGGER = GPIO_TRIGGER_FALLING;
HYPERPIXEL_TOUCH_INTERRUPT_FUNCTION = GPIO_FUNCTION_IN;
HYPERPIXEL_TOUCH_INTERRUPT_PULL = GPIO_PULL_UP;
HYPERPIXEL_TOUCH_INTERRUPT_PIN = GPIO_PIN_27;

Type definitions

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HyperPixel specific types

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PHyperPixelData = ^THyperPixelData;

THyperPixelData = record

Software SPI Data
Device:PGPIODevice;	The GPIO device to use
FSEL:LongWord;	The GPIO function select value
PULL:LongWord;	The GPIO pull select value
CLK:LongWord;	The CLK pin for software SPI
MOSI:LongWord;	The MOSI pin for software SPI
CS:LongWord;	The CS pin for software SPI
Wait:LongWord;	Wait time in milliseconds before display on
Delay:LongWord;	Clock delay time in microseconds

Public variables

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None defined

Function declarations

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HyperPixel functions

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function HyperPixelInitialize(Model:LongWord):LongWord;

Description: Initialize an attached HyperPixel display including GPIO pin configuration

Model	The model of display to be initialized (eg HYPERPIXEL40_SQUARE)
Return	ERROR_SUCCESS on successful completion or another error code on failure
Note	No attempt is made to determine if the model specified matches with the attached display. It is the users responsibility to specify the correct model.

HyperPixel helper functions

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function HyperPixelSPISetup(Data:PHyperPixelData):LongWord;

Description: Setup the software SPI communication used to initialize the HyperPixel display

Data	A pointer to a THyperPixelData structure containing the configuration
Return	ERROR_SUCCESS on successful completion or another error code on failure

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function HyperPixelSPICleanup(Data:PHyperPixelData):LongWord;

Description: Cleanup the software SPI after HyperPixel initialization

Data	A pointer to the THyperPixelData structure used to configure the SPI
Return	ERROR_SUCCESS on successful completion or another error code on failure

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procedure HyperPixelSPIWriteBit(Data:PHyperPixelData; Value:Byte);

Description: Write a single bit to the software SPI

Data	A pointer to the THyperPixelData structure used to configure the SPI
Value	The bit value to write (0 or 1)
Note	Used primarily for HyperPixel 4.0 Rectangle

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procedure HyperPixelSPIWriteByte(Data:PHyperPixelData; Value:Byte);

Description: Write a byte to the software SPI

Data	A pointer to the THyperPixelData structure used to configure the SPI
Value	The byte value to write
Note	Used primarily for HyperPixel 4.0 Rectangle

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procedure HyperPixelSPIWriteRegister(Data:PHyperPixelData; Reg,Value:Byte);

Description: Perform a register select followed by a register write using the software SPI

Data	A pointer to the THyperPixelData structure used to configure the SPI
Reg	The register to be selected
Value	The byte value to write
Note	Used primarily for HyperPixel 4.0 Rectangle

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procedure HyperPixelSPISoftReset(Data:PHyperPixelData);

Description: Perform a software reset of the HyperPixel display

Data	A pointer to the THyperPixelData structure used to configure the SPI
Note	Used primarily for HyperPixel 4.0 Rectangle

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procedure HyperPixelSPISelectPage(Data:PHyperPixelData; Number:Byte);

Description: Perform a page select operation to select a specific configuration page

Data	A pointer to the THyperPixelData structure used to configure the SPI
Number	The page number to select
Note	Used primarily for HyperPixel 4.0 Rectangle

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procedure HyperPixelSPIWriteBits(Data:PHyperPixelData; Value,Count:Word);

Description: Write a sequence of bits to the software SPI

Data	A pointer to the THyperPixelData structure used to configure the SPI
Value	The value containing the bits to be written
Count	The number of bits to write
Note	Used primarily for HyperPixel 2.1 Round and 4.0 Square

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procedure HyperPixelSPIWriteCommand(Data:PHyperPixelData; Command:Word);

Description: Write a command to the software SPI

Data	A pointer to the THyperPixelData structure used to configure the SPI
Command	The command to be written
Note	Used primarily for HyperPixel 2.1 Round and 4.0 Square

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