Industrial Reference Design Platform Vacuum Fluorescent Display VFD and Liquid Crystal Display LCD

1. Industrial Reference Design PlatformVacuum Fluorescent Display (VFD) andLiquid Crystal Display (LCD)

2. 2 Industrial Reference Design PlatformVacuum Fluorescent Display (VFD) and Liquid Crystal Display (LCD)

3. 3 Industrial Reference Design PlatformVFD and LCD – Software Auto-Detect Function Software Auto-Detect: Upon startup of the application function LCD_CHECK is called. The application assumes that the LCD is pulled into the IRD board. The LCD_CHECK function writes a byte of data to the LCD data RAM and then reads back the byte. If the byte read back matches the byte that was written then LCD_CHECK has verified that the LCD is indeed plugged into the IRD. If the byte read back does not match the write byte then the LCD is not plugged in and the application assumes that the VFD is plugged into the IRD. Software Auto-Detect: Upon startup of the application function LCD_CHECK is called. The application assumes that the LCD is pulled into the IRD board. The LCD_CHECK function writes a byte of data to the LCD data RAM and then reads back the byte. If the byte read back matches the byte that was written then LCD_CHECK has verified that the LCD is indeed plugged into the IRD. If the byte read back does not match the write byte then the LCD is not plugged in and the application assumes that the VFD is plugged into the IRD.

4. 4 Noritake Vacuum Fluorescent Display(VFD)Functional Overview A vacuum fluorescent display (VFD) is a display device used commonly on consumer-electronics equipment such as video cassette recorders, car radios, and microwave ovens. Unlike liquid crystal displays, a VFD emits a very bright light with clear contrast and can easily support display elements of various colours. The technology is related to both the cathode ray tube and the nixie tube. Besides brightness, VFDs have the advantages of being rugged, inexpensive, and easily configured to display a wide variety of customized messages. Early on, the main disadvantage of this type of display was the consumption of significantly more power (0.2 watts) than a simple LCD. This was considered a significant drawback for battery-operated equipment like calculators, so VFDs ended up being used primarily in equipment powered by an AC supply or heavy-duty rechargeable batteries. Another advantage is that unlike LCDs, most VFDs continue to function normally in sub-zero temperatures, making them ideal for outdoor devices in cold climates. (From Wikipedia - http://en.wikipedia.org/wiki/Vacuum_fluorescent_display) A vacuum fluorescent display (VFD) is a display device used commonly on consumer-electronics equipment such as video cassette recorders, car radios, and microwave ovens. Unlike liquid crystal displays, a VFD emits a very bright light with clear contrast and can easily support display elements of various colours. The technology is related to both the cathode ray tube and the nixie tube. Besides brightness, VFDs have the advantages of being rugged, inexpensive, and easily configured to display a wide variety of customized messages. Early on, the main disadvantage of this type of display was the consumption of significantly more power (0.2 watts) than a simple LCD. This was considered a significant drawback for battery-operated equipment like calculators, so VFDs ended up being used primarily in equipment powered by an AC supply or heavy-duty rechargeable batteries. Another advantage is that unlike LCDs, most VFDs continue to function normally in sub-zero temperatures, making them ideal for outdoor devices in cold climates. (From Wikipedia - http://en.wikipedia.org/wiki/Vacuum_fluorescent_display)

5. 5 Lumex Liquid Crystal Display (LCD)Functional Overview A liquid crystal display (LCD) is a thin, flat display device made up of any number of color or monochrome pixels arrayed in front of a light source or reflector. It is often utilized in battery-powered electronic devices because it uses very small amounts of electric power. (From Wikipedia - http://en.wikipedia.org/wiki/LCD) HD44780 is an industry standard LCD specification which was developed by Hitachi. Max current consumption is 3.0 mA compared to 400 mA for the VFD. A liquid crystal display (LCD) is a thin, flat display device made up of any number of color or monochrome pixels arrayed in front of a light source or reflector. It is often utilized in battery-powered electronic devices because it uses very small amounts of electric power. (From Wikipedia - http://en.wikipedia.org/wiki/LCD) HD44780 is an industry standard LCD specification which was developed by Hitachi. Max current consumption is 3.0 mA compared to 400 mA for the VFD.

6. 6 Noritake VFDElectrical Specifications The module includes the Vacuum Fluorescent Display glass, VF drivers and micro-controller ICs with refresh RAM, character generator and interface logic. The high speed 8 bit parallel interface is 5V TTL/CMOS compatible suitable for connection to a host CPU bus. The asynchronous serial interface accepts baud rates up to 115,200 with none parity. The module is ready to receive ASCII characters without initialization commends. (From Noritake Web Page: http://www.noritake-itron.com/) The module includes the Vacuum Fluorescent Display glass, VF drivers and micro-controller ICs with refresh RAM, character generator and interface logic. The high speed 8 bit parallel interface is 5V TTL/CMOS compatible suitable for connection to a host CPU bus. The asynchronous serial interface accepts baud rates up to 115,200 with none parity. The module is ready to receive ASCII characters without initialization commends. (From Noritake Web Page: http://www.noritake-itron.com/)

7. 7 Lumex LCDElectrical Specifications

8. 8 Noritake VFDOptical and Environmental Specifications

9. 9 Lumex LCDOptical and Environmental Specifications

10. 10 Noritake VFDParallel Interface Parallel Interfaces: The conventional CPU distributed data method uses a parallel 8 bit data bus. Two bus configurations evolved to provide data transfer control which are known as M68 bus and i80 bus. The M68 bus has an (E)nable clock signal and a direction control signal (R/W).The i80 bus has a separate (/WR) signal for controlling the sending of data and (/RD) for receiving data.Many modules allow either data bus to be connected by configuring a jumper link on the module PCB. Additionally, one of the CPU address lines (A0 through to A15) can be used to select different data registers inside the module via the Rs, C/D or A0 input. This allows many additional display functions to be performed with a single command byte. When several peripheral devices connect to the same data and control bus, a chip select signal (/CS or CS)  (From Noritake Web Page: http://www.noritake-itron.com/)Parallel Interfaces: The conventional CPU distributed data method uses a parallel 8 bit data bus. Two bus configurations evolved to provide data transfer control which are known as M68 bus and i80 bus. The M68 bus has an (E)nable clock signal and a direction control signal (R/W).The i80 bus has a separate (/WR) signal for controlling the sending of data and (/RD) for receiving data.Many modules allow either data bus to be connected by configuring a jumper link on the module PCB. Additionally, one of the CPU address lines (A0 through to A15) can be used to select different data registers inside the module via the Rs, C/D or A0 input. This allows many additional display functions to be performed with a single command byte. When several peripheral devices connect to the same data and control bus, a chip select signal (/CS or CS)  (From Noritake Web Page: http://www.noritake-itron.com/)

11. 11 Noritake VFDSerial Interface Asynchronous Serial Interfaces: Communication is achieved by initiating a change of state in the data signal (start bit) followed by 8 fixed frequency periods (baud rate) for the synchronized transmission of data. This enables a 2 wire solution for many applications with inherent re-synchronization after each 8 bit data byte.Transmission between host and module can be made at CMOS/TTL logic voltage levels over distances up to 0.5 metre. The idle state is logic high with data rates up to 115K bits per second.Greater distance is achieved using RS232 voltage levels (+/-12volts) or a differential system like RS485 which uses two signal wires where the logic level is dependent on the polarity of the wires.  After each data byte, a period is required to allow the module time to process the received data. A hardware control line can be used to indicate to the host that the module is busy. In certain modules an XOFF (13H) character is transmitted to the host to indicate the receive buffer is full. When ready, the module sends the character XON (11H). (From Noritake Web Page: http://www.noritake-itron.com/)Asynchronous Serial Interfaces: Communication is achieved by initiating a change of state in the data signal (start bit) followed by 8 fixed frequency periods (baud rate) for the synchronized transmission of data. This enables a 2 wire solution for many applications with inherent re-synchronization after each 8 bit data byte.Transmission between host and module can be made at CMOS/TTL logic voltage levels over distances up to 0.5 metre. The idle state is logic high with data rates up to 115K bits per second.Greater distance is achieved using RS232 voltage levels (+/-12volts) or a differential system like RS485 which uses two signal wires where the logic level is dependent on the polarity of the wires.  After each data byte, a period is required to allow the module time to process the received data. A hardware control line can be used to indicate to the host that the module is busy. In certain modules an XOFF (13H) character is transmitted to the host to indicate the receive buffer is full. When ready, the module sends the character XON (11H). (From Noritake Web Page: http://www.noritake-itron.com/)

12. 12 Lumex VFDParallel Interface Parallel Interfaces: The data bus of the LCD can be 8 bit or 4 bit. For 4 bit interface only D0-D3 are used. Read/Write commands take 2 cycles in 4 bit mode.Parallel Interfaces: The data bus of the LCD can be 8 bit or 4 bit. For 4 bit interface only D0-D3 are used. Read/Write commands take 2 cycles in 4 bit mode.

13. 13 Noritake VFDSoftware Commands

14. 14 Lumex LCDSoftware Commands

15. 15 Noritake VFD and Lumex LCDASCII Character Set

16. 16 IRD VFD and LCDConnections Support for both VFD and LCD parallel interface Connects to J_VFD 14 pin header LPC2468 GPIOs are used to interface with the VFD/LCD Display Software Auto-Detect: Upon startup of the application function LCD_CHECK is called. The application assumes that the LCD is pulled into the IRD board. The LCD_CHECK function writes a byte of data to the LCD data RAM and then reads back the byte. If the byte read back matches the byte that was written then LCD_CHECK has verified that the LCD is indeed plugged into the IRD. If the byte read back does not match the write byte then the LCD is not plugged in and the application assumes that the VFD is plugged into the IRD.Software Auto-Detect: Upon startup of the application function LCD_CHECK is called. The application assumes that the LCD is pulled into the IRD board. The LCD_CHECK function writes a byte of data to the LCD data RAM and then reads back the byte. If the byte read back matches the byte that was written then LCD_CHECK has verified that the LCD is indeed plugged into the IRD. If the byte read back does not match the write byte then the LCD is not plugged in and the application assumes that the VFD is plugged into the IRD.

17. 17 IRD VFD and LCDJumper Options Supports VFD and LCD parallel interface For the LCD displays, the contrast can be changed using the VR2 (potentiometer)

18. 18 IRD VFD and LCDWriting a byte to the display – Source Code

19. 19 Ported uC/LCD from the HD44780 command set to the Noritake VFD µC/LCD is ‘thread safe’ Possible to invoke µC/LCD functions from multiple tasks in a multitasking environment Transparent to the user µC/LCD uses semaphore services for task-exclusive access to the VFD display IRD VFDuC/OS-II RTOS – uC/LCD Driver µC/OS-II, The Real-Time Kernel is a highly portable, ROMable, very scalable, preemptive real-time, multitasking kernel (RTOS) for microprocessors and microcontrollers. µC/OS-II can manage up to 255 tasks and provides the following services: Semaphores Mutual Exclusion Semaphores (to reduce priority inversions) Event Flags Message Mailboxes Message Queues Task Management (Create, Delete, Change Priority, Suspend/Resume etc.) Fixed Sized Memory Block management Time Management Timer Management µC/OS-II runs on a large number of processor architectures (From Micrium Web Site: http://www.micrium.com/products/rtos/kernel/rtos.html)µC/OS-II, The Real-Time Kernel is a highly portable, ROMable, very scalable, preemptive real-time, multitasking kernel (RTOS) for microprocessors and microcontrollers. µC/OS-II can manage up to 255 tasks and provides the following services: Semaphores Mutual Exclusion Semaphores (to reduce priority inversions) Event Flags Message Mailboxes Message Queues Task Management (Create, Delete, Change Priority, Suspend/Resume etc.) Fixed Sized Memory Block management Time Management Timer Management µC/OS-II runs on a large number of processor architectures (From Micrium Web Site: http://www.micrium.com/products/rtos/kernel/rtos.html)

20. 20 IRD VFD and LCDµC/LCD Interface Functions (Micrium Web Site: http://www.micrium.com) VFD is controlled by writing the appropriate command bytes to the VFD. This can be accomplished with the DispdataWr() and DispDefChar() function.(Micrium Web Site: http://www.micrium.com) VFD is controlled by writing the appropriate command bytes to the VFD. This can be accomplished with the DispdataWr() and DispDefChar() function.

21. 21 IRD VFD and LCDImplementation Example – Display Initialization This is a source code of the initialization of the LCD or VFD display. If (LCD_VFD == 0xA5) determines if the LCD or VFD is plugged in. This is a source code of the initialization of the LCD or VFD display. If (LCD_VFD == 0xA5) determines if the LCD or VFD is plugged in.

22. 22 IRD VFD and LCDImplementation Example – Display Initialization (Cont.) This is the source code to initialized the VFD. This is the source code to initialized the VFD.

23. 23 IRD VFD and LCDImplementation Examples

24. 24 IRD VFD and LCDMore Implementation Examples

25. 25 IRD VFDGraphics Mode Only the VFD support a graphic mode. This is another benefit of the VFD over the LCD.Only the VFD support a graphic mode. This is another benefit of the VFD over the LCD.

26. 26 IRD VFDGraphics Mode Example

27. 27 IRD VFDGraphics Mode Example – Displaying the Image

28. 28 IRD VFD Exercise 1Brightness Control

29. 29 IRD VFD Exercise 1Brightness Control – Solution…DispBrightness Function

30. 30 IRD VFD Exercise 1Brightness Control – Solution… Keypad_Map function

31. 31 IRD VFD Exercise 2Graphics Mode

32. 32 IRD VFD Exercise 2Graphics Mode - Solution

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