Reference Design: Low-Cost Implementation of TFT Displays in Microcontroller Applications

With the increasing spread of PDA and Smartphone, the requirements of users on the MMI interfaces of products like data loggers, handheld measuring devices, medical equipment, wending machines and electronic payment systems are also steadily rising. In many cases these demands can no longer be fulfilled by using LCD modules – IPC platforms are often much too complex and too expensive and are subjected to continuous product migration of the processor market. In addition, the value of many products can be enhanced just by adding colored surfaces and touch functions.

While passive LCDs up to a resolution of QVGA (Quad VGA) can quite easily be controlled with a microcontroller, the control of TFTs is more extensive and requires much more computing power. The TFTs require a parallel TTL interface. The synchronization either takes place via HSYNC/VSYNC or a DATA ENABLE signal. Due to the fact that a TFT does not have a frame-buffer on board, the microcontroller has to constantly transfer the image data from an external memory to the TFT using a fixed timing.

With the VisuRDK kits MSC presents an economic solution for the direct control of TFT displays using a general purpose microcontroller. With the intelligent hard and software combination, a TFT display can be controlled directly and without an additional graphics controller. The system costs can be significantly reduced by omitting the graphics controllers used so far in such applications. This microcontroller-based approach of the VisuRDK kits offer an interesting alternative for applications where the embedded PC solution or the use of an expensive graphics subsystem would be much too powerful and expensive.

The kit is a fast and easy introduction to graphic programming for developers. Graphic interfaces can be quickly created and tested with the help of graphics libraries and program examples. Within the shortest time, you can adapt the examples to your own requirements. The software drivers are provided in the source code and the touch panel support is also integrated. Besides the provided QVGA TFT with touch, the kit also offers support for TFT displays from different manufacturers.

The kit also contains a complete microcontroller developer environment including IDE, complier (test license) as well as an E10A-JTAG emulator.

The new reference designer kit (item number: VISURDK-H8SX-VGA) is available as of October 2008 and features the following function extent:

Hardware:
H8SX/1668R board with 2 MB SRAM and 8 MB SDRAM external, USB 2.0, Ethernet (SMSC9218), SD card slot, 3.5" QVGA TFT with touch, set of cables, E10A USB JTAG debugger, power- supply and documentation.

Software:
Renesas HEW4 Embedded Workbench, C-compiler (test license), Flash programming toolset, graphic software, TFT driver.

The heart of this new kit is the H8SX/1668R from Renesas, a general purpose 32 bit microcontroller with 50 MHz single-cycle H8SX CPU featuring:

• Timer unit with 12 x 16 bit timers
• PPG pulse generator for controlling stepper motors
• 2 x 8 bit timer
• Watchdog
• 6 x USARTs (optional high-speed SSI, smart card interface, CRC hardware)
• 2 x I2C bus
• USB 2.0 (function)
• A/D converter, D/A converter
• JTAG interface
• QFP-144, µBGA-176
   

Whitepaper-Download (171 KB)