NXP LED Dimmer Demoboard


The LED dimmer demoboard demonstrates the capability of the I2C-bus to perform red/green/blue color LED lighting and mixing operations. Two separate control cards comprise the demoboard:

  • The Keypad Control Card contains a microcontroller, a 16-key keypad/controller, and a power supply/regulator module.
  • The LED Control Card contains LEDs (red, green, blue, white, RGB) and the devices used to control them.

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The two control cards directly connect to each other without the need of external cables.

The keypad control card contains an NXP P89LV51RD2 microcontroller interfacing with a NXP PCA9564 I2C-bus controller to generate the I2C commands. The microcontroller is programmed to allow the 16-key keypad to control the RGB color mixing, generate fun light patterns, and emulate battery status monitoring. The LED control card accepts input from the keypad control card’s keypad. Power is supplied to the LED dimmer demoboard via the keypad control card by either an external 9V power supply or by a 9V battery.

The control devices on the demoboard are:

  • NXP P89LV51RD2 microcontroller master controlling all the I2C slave devices on the demoboard with embedded firmware.
  • NXP PCA9564 I2C-bus controller interfacing between the microcontroller and the I2C-bus via an 8-bit parallel port and control signals.
  • NXP PCA9555PW 16-bit GPIO controlling the 16-key keypad.
  • Four NXP PCA9531PW 8-bit LED dimmers and one NXP PCA9533DP/01 4-bit LED dimmer controlling the LED dimming and color mixing.

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Firmware in the P89LV51RD2 microcontroller emulates a cell phone application. It generates fun patterns and controls the brightness of a virtual display. A battery discharge emulation with a visual charge status can also be performed. The firmware is intended to show a specific application (cell phone), but the demoboard can be used and reprogrammed externally for any application that requires keypad control and LED lighting/color mixing. Most of the code, written in C language, has been borrowed from the PCA9564 Evaluation Board (drivers and main interfacing files between the P89LV51RD2 and the PCA9564). Only the upper layer files have been modified to implement the code specific to the LED Dimmer Demoboard. Programming has to be performed using an external microcontroller programmer or the PCA9564 Evaluation Board Kit.

The default firmware in the P89LV51RD2 allows the user to:

  • Control the 16-key keypad (numbers from 0 to 9 are displayed in binary code)
  • Control the RGB LEDs and program 3 different colors/display speeds via the keypad
  • Control the brightness of the white LEDs through the keypad
  • Emulate a battery discharge scenario
  • Enable a Demo Mode showing fun light application/RGB mixing

The P89LV51RD2 can be programmed with any user-defined firmware. The demoboard, however, does not have any built-in programming functionality, so the user must program the microcontroller with an external programmer or the PCA9564 Evaluation Board Kit.

For more information about the PCA9564 Evaluation Board, its drivers and code, refer to:

  • AN10149 PCA9564 Evaluation Board V2 (Aug 19, 2004)
  • PCA9564 Evaluation Board Main Page



  • LED Dimmer Demoboard Keypad Control Card Schematics
  • LED Dimmer Demoboard LED Control Card Schematics

Source Code

Below is C language source code for programming the P89LV51RD2 microcontroller. Please check back occasionally for the latest revisions.

  • P89LV51RD2 Microcontroller Source Code

Application Notes

  • AN10315 LED Dimmer Demoboard V1 (Jan 7, 2005)

 3rd-Party Tools

Below are links to third party software tools that you can use with the demoboard. (Disclaimer: Access, use, and support of these tools is subject to conditions set by the third parties.)

Flash Magic

Flash Magic can be obtained from Embedded Systems Academy. This software can be used to load the microcontroller with compiled hex files. Please visit http://www.esacademy.com/software/flashmagic/ for more information, release notes, application notes, and to obtain the software. Flash Magic is sponsored by NXP Semiconductors.


The Raisonance 8051 Development Kit, from American Raisonance, may be used to develop, debug, and compile C language code. Please visit http://www.amrai.com/amrai.htm for more information. To obtain an evaluation version of the software which allows you to compile up to 4Kb of code:

  1. Visit the link above.
  2. Under the Software heading in the yellow box, click 8051.
  3. Complete the evaluation form.
  4. Download GettingStartedManual.pdf.
  5. Download and install kit51.exe.

The full development kit can also be purchased through the American Raisonance sales department.