Assessments - 4, GPA: 4
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The display is interfaced with a simple SPI interface to send and receive commands and data. The Xplain kit provides tested low–level drivers and high- level functions in order to get the developer quickly up to speed with his application development. Figure 1-1. Display Xplained evaluation module. 8-bit Microcontrollers Application Note Rev. 8297A-AVR-04/10 Datasheet for the LCD module (ET024006DHU) from EDT can be found here: Datasheet for the graphical controller (HX8347-A) from Himax can be obtained by contacting EDT. It may also found on the web. Firmware for Xplain kit can be found here: Also checkout these application note: • AVR1913: Display Xplained Firmware – Getting Started training • AVR1921: Reprogramming the Xplain AT90USB1287 and ATxmega128A1 • AVR1922: Xplain Board Controller Firmware 3 General information The LCD module (ET024006DHU from EDT) has a 240 x 320 pixel resolution, with up to 6 bit pr color, giving 256k colors. The Display Xplained board uses a regular 4-wire SPI interface to access the display. The touch interface is a 4-wire resistive touch that should be interfaced to ADC/IO pins to work. The backlight system has three white LEDs in parallel that can draw up to 60mA at 3.3V. For further details see the datasheet from EDT. Figure 3-1. Overview of the Xplain kit backside. AVR1909 8297A-AVR-04/10 3.1 3.1 3.2 The Touch module 3.3 The Backlight module AVR1909 The Display Xplained module is quite simple. It basically connects the TFT display SPI interface, resistive touch interface, and backlight interface from a 40pin FPC connector to two female pin-headers that fit the Xplain kit. In addition it has a program/debug interface that will connect an external programmer/debugger to the Xplain kit through a male and a female pin-header. The LCD module is produced by EDT (Emerging Display Technologies Corp), and is called ET024006DHU. It will be replaced with a new version called ET024008DHU in mid 2010 that have the same outline dimension and same electronics and optical specification. The LCD module embeds a graphical controller/driver from Himax called HX8347-A. This controller provides several communication interfaces like 8/16bit parallel MCU interface, 16/18bit RGB, and 4-wire serial SPI interface. On the Display Xplained module this has been hardwired to use serial SPI interface. The display is attached to the PCB with a strong dual-sided foam tape adhesive that make it easy to mount. This will electrically insulate the display from the PCB avoiding any short-circuit problems that may be caused by vibration wearing on the solder mask and tracks/vias. It will also provide some vibration damping for the display to protect the glass surface from cracking. It is also quite easy to remove the display if needed. The LCD module has a 4-wire resistive touch interface. This consists of four lines (2 in each X and Y direction) that should be connected to ADC/IO pins on the MCU interfacing it. The general procedure is to apply a voltage (VCC) for instance on the X-lines and then measure the voltage on the Y-lines. Then the operation is repeated, but switching the X and Y lines. This will give a (X,Y) coordinate for the touch. In order to avoid over driving (saturate) the ADC inputs, serial resistors have been added so the maximum voltage is within the ADC capability. This is a very simple and low-cost solution to adjust the touch sensor output to fit the ADC inputs. It will also lower the current consumption a little to increase the overall power performance. For more details on how to use 4-wire resistive touch sensors, see the application note AVR341: Four and five-wire Touch screen Controller using tinyAVR® and megaAVR® devices The backlight module of the display consists of three white LEDs connected in parallel. These can draw up to 60mA and have a maximum voltage drop up to 3.6V. On the Display Xplained module the backlight is connected to the V3P3 (3.3V) power- supply. This will somewhat limit the maximum light output in change of a simpler design. A MOSFET turns the backlight LEDs on/off and a 4.7ohm resistor limits the maximum current through the LEDs. This makes it quite easy to control the backlight with a PWM signal to adjust intensity. 8297A-AVR-04/10 The SPI interface The Display Xplained module uses a simple SPI interface to communicate with the LCD module. This consist of a Chip-Select (CS) line, a clock line (SCL), and two data lines (SDI/SDO). The SPI is operated in mode 3, i.e. inactive clock i...
Este manual também é adequado para os modelos :TV - AVR1909 (339.47 kb)
TV - AVR1909 (339.47 kb)