Unit HyperPixel

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Description

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 

display_lcd_rotate=0

Rotate 90 degrees clockwise 

display_lcd_rotate=1

Rotate 180 degrees clockwise 

display_lcd_rotate=2

Rotate 270 degrees clockwise 

display_lcd_rotate=3

Horizontal flip 

display_lcd_rotate=0x10000

Vertical flip 

display_lcd_rotate=0x20000

Constants


HyperPixel model HYPERPIXEL*
HYPERPIXEL40_RECTANGLE = 0;  
HYPERPIXEL40_SQUARE = 1;  
HYPERPIXEL40_SQUARE2021 = 2;  
HYPERPIXEL21_ROUND = 3;  


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);  


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_DELAY_ALT = 10; Clock pulse time in microseconds (Rectangle model)
HYPERPIXEL_SPI_WAIT_ALT = 200; Wait time in milliseconds before display on (Rectangle model)


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;  


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;  


HyperPixel touch interrupt pins (All Models) (GPIO for touch event registration) HYPERPIXEL_TOUCH_*
HYPERPIXEL_TOUCH_INTERRUPT_FUNCTION = GPIO_FUNCTION_IN;  
HYPERPIXEL_TOUCH_INTERRUPT_PULL = GPIO_PULL_UP;  
HYPERPIXEL_TOUCH_INTERRUPT_PIN = GPIO_PIN_27;  


Type definitions


HyperPixel specific types

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

None defined

Function declarations


HyperPixel functions 

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 

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 


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 


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 


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 


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 


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 


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 


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 


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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