LCD wiki MRB3514 3.5inch 16bit Parallel Port RTP and CTP Module User Manual

: June 14, 2024
: LCD wiki

LCD wiki MRB3514 3.5inch 16bit Parallel Port RTP and CTP Module

Product Description

The product is a 3.5-inch TFT LCD display module which supports switching between resistance touch screen and capacitive touch screen. It has 480×320 resolution, supports 16BIT RGB 65K color display, and the internal driver IC is ILI9488, which uses 16-bit parallel port communication. The module includes LCD display, resistance touch screen or capacitance touch screen and PCB backplane. It can be plugged into the TFT LCD slot of the STM32 series development board or used on the C51 platform.

Product Features

3.5-inch color screen, support 16BIT RGB 65K color display, display rich colors
320×480 resolution for clear display
Support 16-bit parallel data bus mode switching, fast transfer speed
Supports ALIENTEK STM32 Mini, Elite, WarShip, Explorer, and Apollo development boards direct plug-in use
Support switching between resistance touch screen and capacitive touch screen
Provides a rich sample program for STM32 and C51 platforms
Military-grade process standards, long-term stable work
Provide underlying driver technical support

Product Parameters

Interface Description

NOTE:

The hardware of the module supports switching between resistance touch screen and capacitive touch screen:
- Use resistance touch screen: solder the components in the dotted line box of RTOUCH, and do not need to weld the components in the dotted line box of CTOUCH;
- Use capacitive touch screen: solder the components in the dotted line box of CTOUCH, and do not need to weld the components in the dotted line box of RTOUCH;
This module can be directly inserted into the TFTLCD slot of the punctual atom development board, no manual wiring is required.
The hardware of this module only supports 16 bit mode

Important Note:

The following pin numbers 1~34 are the pin number of Module pin with PCB backplane of our company. If you purchase a bare screen, please refer to the pin definition of the bare screen specification, refer to the wiring according to the signal type instead of directly Wire according to the following module pin numbers. For example: CS is 1 pin on our module. It may be x pin on different size bare screen.
About VCC supply voltage: If you buy a module with PCB backplane, VCC/VDD power supply can be connected to 5V or 3.3V (module has integrated ultra low dropout 5V to 3V circuit), if you buy a bare screen LCD, remember to only connect 3.3V.
About the backlight voltage: The module with the PCB backplane has integrated triode backlight control circuit, which only needs to input the high level of the BL pin or the PWM wave to illuminate the backlight. If you are buying a bare screen, the LEDAx is connected to 3.0V-3.3V and the LEDKx is grounded.

Hardware Configuration

The LCD module hardware circuit comprises six parts: an LCD display control circuit, a power control circuit, a Impedance balance adjusting circuit, a capacitive touch screen control circuit , a resistance touch screen control circuit and a backlight control circuit. LCD display control circuit for controlling the pins of the LCD, including control pins and data transfer pins.
Power control circuit for stabilizing the supply voltage and selecting the external supply voltage.
The impedance balance adjusting circuit is used to balance the impedance between MCU pin and LCD pin.
resistance touch screen control circuit is used to control touch screen interrupt acquisition, data sampling, AD conversion, data transmission, etc
Capacitive touch screen control circuit is used to control touch screen interrupt acquisition, data sampling, AD conversion, data transmission, etc.
A backlight control circuit is used to control the brightness of the backlight.

Working principle

Introduction to ITI9488 Controller

The ITI488 controller supports a maximum resolution of 320*480 and has a 345600-byte GRAM. It also supports 8-bit, 9-bit, 16-bit, 18-bit and 24-bit parallel port data buses. It also supports 3-wire and 4-wire SPI serial ports. Since the supported resolution is relatively large and the amount of data transmitted is large, the parallel port transmission is adopted, and the transmission speed is fast. ITI9488 also supports 65K, 262K and 16.7M RGB color display, display color is very rich, while supporting rotating display and scroll display and video playback, display in a variety of ways.
The ITI9488 controller uses 16bit (RGB565) to control a pixel display, so it can display up to 65K colors per pixel. The pixel address setting is performed in the order of rows and columns, and the incrementing and decreasing direction is determined by the scanning mode. The ITI9488 display method is performed by setting the address and then setting the color value.

Introduction to parallel port communication

The parallel port communication write mode timing is as shown below: The timing of the parallel port communication read mode is shown in the figure below: CSX is a chip select signal for enabling and disabling parallel port communication, active low
RESX is an external reset signal, active low
D/CX is the data or command selection signal, 1-write data or command parameters, 0-write command
WRX is a write data control signal
RDX is a read data control signal
D[X:0] is a parallel port data bit, which has four types: 8-bit, 9-bit, 16-bit, and 18-bit.
When performing a write operation, on the basis of the reset, first set the data or command selection signal, then pull the chip select signal low, then input the content to be written from the host, and then pull the write data control signal low. When pulled high, data is written to the LCD control IC on the rising edge of the write control signal. Finally, the chip select signal is pulled high and a data write operation is completed.
When entering the read operation, on the basis of the reset, first pull the chip select signal low, then pull the data or command select signal high, then pull the read data control signal low, and then read the data from the LCD control IC. And then The read data control signal is pulled high, and the data is read out on the rising edge of the read data control signal. Finally, the chip select signal is pulled high, and a data read operation is completed.

Instructions for use

STM32 instructions

Wiring instructions:
See the interface description for pin assignments.
Note:

This module can be directly inserted into the TFTLCD slot of the punctual atom development board, no manual wiring is required.
The following internal plug-in pins of the corresponding MCU refer to the MCU pins directly connected to the TFTLCD slot inside the development board, only for reference.

Operating Steps：

A. Connect the LCD module(As shown in Picture 1) and the STM32 MCU according to the above wiring instructions, and power on;
B. Select the C51 test program to be tested, as shown below:
(Please refer to the test program documentation for the test program description.)
C. Open the selected test program project, compile and download; detailed description of the STM32 test program compilation and download can be found in the following document:
http://www.lcdwiki.com/res/PublicFile/STM32_Keil_Use_Illustration_EN.pdf
D. If the LCD module displays characters and graphics normally, the program runs successfully；

C51 instructions

Wiring instructions:
See the interface description for pin assignments.
Note:

Since the input and output levels of the GPIO of the STC12C5A60S2 microcontroller are 5V, the capacitive touch IC cannot work normally (only 1.8~3.3V can be accepted). If you want to use the capacitive touch function, you need to connect to the level conversion module;
Since the STC89C52RC microcontroller does not have a push-pull output function, the backlight control pin needs to be connected to a 3.3V power supply to be properly lit.
Since the STC89C52RC microcontroller’s Flash capacity is too small (less than 25KB), the program with touch function cannot be downloaded, so the touch screen does not need wiring.

Operating Steps：

A. Connect the LCD module (As shown in Picture 1)and the C51 MCU according to the above wiring instructions, and power on;
B. Select the C51 test program to be tested, as shown below:
(Test program description please refer to the test program description document in the test package)
C. Open the selected test program project, compile and download;
detailed description of the C51 test program compilation and download can be found in the following document:
http://www.lcdwiki.com/res/PublicFile/C51_Keil%26stc- isp_Use_Illustration_EN.pdf
D. If the LCD module displays characters and graphics normally, the program runs successfully；

Software Description

Code Architecture

A. C51 and STM32 code architecture description The code architecture is shown below:
- The Demo API code for the main program runtime is included in the test code;
- LCD initialization and related bin parallel port write data operations are included in the LCD code;
- Drawing points, lines, graphics, and Chinese and English character display related operations are included in the GUI code;
- The main function implements the application to run;
- Platform code varies by platform;
- The IIC code is used by the capacitive touch IC GT911, including IIC initialization, data writing and reading, etc;
- Touch code includes two parts: resistance touch screen code and capacitance touch screen (gt911) code;
- The key processing related code is included in the key code (the C51 platform does not have a button processing code);
- The code related to the led configuration operation is included in the led code(the C51 platform does not have a led processing code);

GPIO definition description

A. STM32 test program GPIO definition description
The GPIO definition of the LCD screen of the STM32 test program is placed in the lcd.h file, which is defined in two ways:
- STM32F103RCT6 microcontroller test program uses IO analog mode (it does not support FSMC bus)
Other STM32 MCU test programs use FSMC bus mode STM32F103RCT6 MCU IO analog test program LCD screen GPIO definition as shown below:
- FSMC test program lcd screen GPIO is defined as shown below (take STM32F103ZET6 microcontroller FSMC test program as an example):
- STM32 platform touch screen related code contains two parts :resistance touch screen code and capacitance touch screen code.
- Resistance touch screen GPIO definition is placed in the rtp.h file as shown below (take the STM32F103ZET6 microcontroller IO analog test program as an example): The capacitance touch screen related GPIO definition consists of two parts: IIC’s GPIO definition and screen interrupt and reset GPIO definition.
- The IIC GPIO definition is placed in the ctpiic.h file as shown below (take the STM32F103RCT6 microcontroller FSMC test program as an example):
- The interrupt of the touch screen and the reset GPIO definition are placed in GT911.h, as shown in the following figure (take the STM32F103ZET6 microcontroller FSMC test program as an example):
B. C51 test program GPIO definition description
C51 test program lcd screen GPIO definition is placed in the lcd.h file, as shown below(Taking the STC12C5A60S2 microcontroller test program as an example): Parallel pin definition needs to select the whole set of GPIO port groups, such as P0, P2, etc., so that when transferring data, the operation is convenient.Other pins can be defined as any free GPIO.
C51platform touch screen related code contains two parts :resistance touch screen code and capacitance touch screen code.
- Resistance touch screen GPIO definition is placed in the rtp.h file as shown below (Taking the STC12C5A60S2 microcontroller test program as an example): The capacitance touch screen related GPIO definition consists of two parts: IIC’s GPIO definition and screen interrupt and reset GPIO definition.
- The IIC GPIO definition is placed in the gtiic.h file as shown below (take the STC12C5A60S2 microcontroller test program as an example):
- The interrupt of the screen and the reset GPIO definition are placed in GT911.h, as shown in the following figure (take the STC12C5A60S2 microcontroller test program as an example): The GPIO definition of the touch screen can be modified and can be defined as any other free GPIO.

Parallel port communication code implementation

A. STM32 test program parallel port communication code implementation
The STM32 test program parallel port communication code is placed in the LCD.c file, which is implemented in two ways:
- STM32F103RCT6 microcontroller test program uses IO analog mode (it does not support FSMC bus)
- Other STM32 MCU test programs use FSMC bus mode
  The IO simulation test program is implemented as shown below: The FSMC test program is implemented as shown below: Both 8- and 16-bit command writes and 8- and 16-bit data writes and reads are implemented.
B. C51 test program parallel port communication code implementation
- The relevant code is implemented in the LCD.c file as shown below: Implemented 8-bit and 16-bit commands and 8-bit and 16-bit data write and read.

4. touch screen calibration instructions

A. STM32 test program touch screen calibration instructions
The STM32 touch screen calibration program automatically recognizes whether calibration is required or manually enters calibration by pressing a button.
It is included in the touch screen test item. The calibration mark and calibration parameters are saved in the AT24C02 flash. If necessary, read from the flash. The calibration process is as shown below:
B. C51 test program touch screen calibration instructions
The C51 touch screen calibration needs to execute the Touch_Adjust test item (only available in the STC12C5A60S2 test program), as shown below: After the touch calibration is passed, you need to save the calibration parameters displayed on the screen in the touch.c file, as shown below:

Common software

This set of test examples requires the display of Chinese and English, symbols and pictures, so the modulo software is used.
There are two types of modulo software:
Image2Lcd and PCtoLCD2002. Here is only the setting of the modulo software for the test program.
The PCtoLCD2002 modulo software settings are as follows:

Dot matrix format select Dark code the modulo mode select the progressive mode
Take the model to choose the direction (high position first)
Output number system selects hexadecimal number
Custom format selection C51 format

The specific setting method is as follows:
http://www.lcdwiki.com/Chinese_and_English_display_modulo_settings
Image2Lcd modulo software settings are shown below: The Image2Lcd software needs to be set to horizontal, left to right, top to bottom, and low position to the front scan mode.