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Instruction of External Keyboard of STONE TFT LCD Module Resistive Touch Panel

Resistive touch panel is widely used in various industries such as industrial control and instrumentation because of its high performance-price ratio and simple human-computer interaction. However, in severe application such as heavy oil stain, humidity, and strong light, etc., there are many faults in the use of touch panel, which mainly reflected int the failure of touch button, mainly due to the layered structure of the resistive touch panel.

 

For the long-term in the wet, oil, strong ultraviolet outdoor applications and other particularly harsh environment, it is recommended to use external mechanical keys instead of touch panel. The Intelligent TFT LCD Module offers a solution with the easy-to-use mechanical keyboard that can replace the touch panel.

 

Ⅰ. Failure analysis of resistive touch panel

 


 Resistive Touch Panel

 

Figure. 1 Resistive Touch Panel

 

The resistive touch panel is divided into upper and lower layers, the upper layer is PET film, and the lower layer is glass. There are conductive coat, surrounding circuit and press-bonded FPC wiring between the layers.When a liquid solvent such as water or oil enters the FPC pressing port, there will be a risk that the FPC adjacent electrodes may be short-circuited or that the FPC electrodes may burn out due to a large current generated between the electrodes. Whether the electrode is short circuit or open circuit, it will lead to the touch button failure of no response.

All resistive touch panels of our company have waterproof and dust-proof design, but can not guarantee the long-term contact with water without failure. It is more difficult to avoid the failure, if it is oil solvent.

 

Improvement scheme for whole machine structure of resistive touch panel:

 

1. Put the touch panel cable at the upper end of the display screen as far as possible, as shown in Figure 2, avoid water droplets converging at the FPC Pressing point position (all Intelligent TFT LCD Modules support 180-degree software rotation function);

 

2. As shown in Figure 3, the whole PET film is stuck on the outside of the casing to isolate the touch panel from the external environment to prevent the solvent from entering;

 

Rotate 180-degree  

Figure. 2  Rotate 180-degree             

         

Effect drawing of PET film on the whole surface of the case

Figure. 3 Effect drawing of PET film on the whole surface of the case

 

3. Paste the frame-shaped protective tapeon the external edge of the touch panel to protect the gap between the PET film of the touch panel and the glass end face from solvent entering.

 

4. Use the capacitive touch panel instead of resistive touch panel.Since the materials and technology of the two touch panel are different, in the same environment, the dust-proof and moisture-proof effect of the capacitive touch panel will be better.

 

Ⅱ. Instructions of external keyboard of Intelligent TFT LCD Module

 

The basic touch controls of Intelligent TFT LCD Module include “Button,”“Button Key Value Return” and “Button States Return”. The attributes of Area Range Settings for all three buttons are the same, as shown in Figure 4. Function of “Button 0” in Figure 4: Pressing this button will first display the effect of anti-color animationon Page 10 at its position, and then switch to Page 1.

 

 “Button 0” and its attributes settings

Figure. 4 “Button 0” and its attributes settings

 

The basic trigger mode of the button is to define the position of the touch button on the page through “X / Y coordinate, width / height”, and the function of the button will be executed when the area is pressed.In addition, two additional button triggering modes can be provided through the “key code”: One is triggered by the external keyboard of the Intelligent TFT LCD Module, and the other is triggered by the command 0x80 through the 4F register. The above three triggering modes will perform the same button function.

 

Touch the trigger button is to press the effective area of the button. The triggering through the external keyboard of the Intelligent TFT LCD Module and 4F register are both realized by using the “key code” in the button attributes settings.

 

2.1 Trigger the button by 4F register

 

This mode is supported by all Intelligent TFT LCD Module. It requires the external keyboard connected with MCU, and number each key on the keyboard (key code). When the user MCU determines that a key is pressed, the key code of the key will be written into the 4F register of the Intelligent TFT LCD Module through the command 0x80. After the HMI receives the key code from the 4F register, it will match the button on the display page, find the button whose setting value of "key code" in the button attributes is the same as the received key code, and execute the function of this button.

 

This mode supports up to 256 keys with key code numbers from 0 to 255. For example, the "key code" of Button 0 in Figure 4 is set to 15. When the user MCU writes the value 15 to the 0x4F register through the command 0x80, the function of “Button 0” on the page is executed.

Command sent by user MCU: A5 5A 03 804F 0F

A5 5A: Frame header

03: Length of command

80: Write register command

4F: Register address

F: Key code

 

2.2 Use Intelligent TFT LCD Module external keyboard to trigger the button

 

The 2.2.1 Intelligent TFT LCD Module supports external devices - - Keyboard interface

 

Only part of the Intelligent TFT LCD Module provides the function that requires Intelligent TFT LCD Module to support external devices with keyboard interface. Whether the Intelligent TFT LCD Module supports the keyboard interface can be specifically inquired through the "Supporting External Devices"of the product specification.

 

Support peripherals

Parameter

Data

Buzzer

Support

RTC(real-time clock)

Support

Audio and video

Support the picture playing and sound output with speaker power of 8 ohms and 2 watts.

Keyboard interface

Support the external matrix keyboards of up to 8 rows and 8 columns and should be used in conjunction with KAP02.

USB disk interface

Support. Used to download or copy user data offline.

USB-mini interface

Support. Used to download or debug online.

Storage space

128M bytes/ 1G bits (support the pictures in JPG format with the theoretical storage of up to 65536 pictures).

Figure. 5 List of External Devices Supported in Product Specification

 

2.2.2 Matrix keyboard of 8 rows 8 columns

 

The Intelligent TFT LCD Module keyboard interface supports the matrix keyboard of 8 rows * 8 columns with a maximum of 64 keys. As shown in Figure. 6, each key must be numbered (coded) in a coding range of 0 to 63 in accordance with the illustrated method.


Keyboard Row and Column Connection and Key Code Allocation

Figure. 6 Keyboard Row and Column Connection and Key Code Allocation

 

2.2.3 Button triggering mode

 

When the Intelligent TFT LCD Module detects that a key is pressed, the key code is acquired and matched with the button on the display page. Find the button whose setting value of the key code in the button attributes is the same as the detected key code, and perform the function of the button.

 

This mode supports up to 64 keys with the effective key code number from 0 to 63. For example, the “key code” of Button 0 in Figure 4 is set to 15. When the Intelligent TFT LCD Module detects that the position key at Row1 / Clm7 is pressed, the function of “Button 0” on the page will be executed.

 

2.2.3 Keyboard adapter plate (KAP02)

 

The Intelligent TFT LCD Module keyboard interface must be connected to the matrix keyboard through the keyboard adapter plate KAP02, as shown in Figure 7. The KAP02 circuit and the matrix keyboard can also be made on the same circuit board according to the schematic diagram of the keyboard adapter plate KAP02 as shown in Figure 9.

 

The keyboard adapter plate KAP02 has two sockets, one is a FPC socket of 6 PIN 1.0 pitch for connecting the keyboard interface of the Intelligent TFT LCD Module, the other is a single row of curved pins of 16 PIN 2.54 pitch for connecting up to 8 rows and 8 columns of matrix keyboard.

Physical drawing of the keyboard adapter plate KAP02

Figure.7: Physical drawing of the keyboard adapter plate KAP02.         

Dimension drawing of the keyboard adapter plate KAP02

Figure.8: Dimension drawing of the keyboard adapter plate KAP02

 

Circuit schematic diagram of KAP02

Figure. 9 Circuit schematic diagram of KAP02

 

For detailed instructions of the “Button,” Button Key-Value Return” and “Button State Return” controls, please refer to the User Development Guide for Intelligent TFT LCD Module.

 

The following links may help you

 

14 STONE TOOLBOX instruction tutorial

https://www.stoneitech.com/news/instructions