With the ever-changing pace of the semiconductor lighting industry, high-brightness LEDs with long life, low energy consumption, flexible application, environmental protection and other advantages are gestating a new industrial revolution - the lighting revolution, making our lives and The working environment is glamorous and colorful. However, because LEDs themselves are characteristic of semiconductor devices, LED lighting design faces two major challenges - LEDs of the same color have multiple models and specifications, and LED performance is degraded with temperature. This requires lighting engineers to make LED model specifications and temperature compensation considerations when designing LED lighting color mixing. LED model specifications and temperature compensation algorithm design are not only complex, but also require lighting engineers to have a more professional knowledge of color theory. This has led many lighting design engineers to avoid complicated LED model specification compensation algorithm design by designing and producing LEDs with specified specifications. But this will bring an increase in cost to the entire system, because LED suppliers usually charge an additional 10% of the designation fee. In order to help the majority of lighting design engineers solve the challenge of LED color mixing design, this paper introduces a Cypress-based EZ-Color controller that does not require the specification of LED models, and can quickly and easily complete a high-performance LED lighting with excellent performance. Color mixing design.
The EZ-Color controller is a programmable system-on-chip chip from Cypress for high-brightness LED lighting color mixing applications. It is mainly composed of 8-bit microprocessor, programmable analog module and digital module, plus hardware multiply accumulator, I2C, Flash, SRAM and other peripheral peripheral modules.
Therefore, in addition to the calculation control function of the general LED color mixing system, the EZ-Color controller can flexibly realize the required analog and digital peripheral functions according to the specific requirements of the color mixing system through programmable analog and digital modules. For example, the EZ-Color controller CY8CLED16 with 16 programmable digital modules can be integrated to realize the LED lighting color mixing system of up to 16 LED control channels. It can also be designed as a 32-bit resolution 4-channel LED control channel. Color mixing system. In order to facilitate the user to achieve high-brightness LED color mixing design simply and quickly, Cypress built a three-color LED color mixing module based on EZ-Color controller and codeless design software. This color mixing module has been configured with PSoC internal registers, programmable module internal wiring, LED model specifications and temperature compensation algorithm software. When users need to design the lighting color mixing system, just select the three-color LED color mixing driver as the windows operation and drag and drop it into the PSoC express design area. All the lighting color mixing software will be automatically generated.
EZ-Color's high-brightness LED lighting color mixing design is based on Cypress's codeless graphical design software, PSoC express. When the user wants to complete the design of a system, it is only necessary to perform simple operations. The first step is the input and output driver selection; the second step is to define the behavior relationship or transfer function relationship between the output and the input. The EZ-Color color mixing scheme is no exception. It is also composed of input, output drive and transfer function relationships.
As can be seen from the above implementation mechanism diagram, EZ-Color's LED color mixing scheme uses (x, y, Y) to represent the input, and the output is RGB three-color LED. The hardware driver of the three-color LED uses SSDM (random signal strength). Modulation) User Module. The input (x, y, Y) is the color input request information of EZ-Color according to the characterization method of CIE 1931 chromaticity diagram, that is, x, y represents hue and color saturation, and reflects chromaticity information of color, and Y Represents luminous flux and reflects the brightness information of the color. The SSDM User Module is a hardware implementation of Cypress's PrISM (Precision Signal Strength Modulation) technology. PrISM technology is Cypress's proprietary LED brightness adjustment technology, which effectively solves electromagnetic interference and low frequency flicker problems.
Conventional LED brightness control is achieved by using a pulse width modulated signal (PWM signal), which is adjusted by changing the aspect ratio. This method of brightness adjustment is simple, but since the PWM signal is a signal that is fixed at high and low levels, its harmonic components are very rich and electromagnetic interference is large. At the same time, when the low-frequency PWM signal is used for brightness control, the human eye will notice that the light is blinking.
The brightness control of the EZ-Color solution uses Cypress's proprietary PrISM technology. Compared with the PWM control method, it can effectively solve the electromagnetic interference and low frequency flicker problems. The PrISM technology compares the random counter with the value of the signal strength register requested by the user. If the value in the random counter is less than the signal strength value, it outputs a high level signal, and when it is large, it outputs a low level, thereby generating a high level. An accurate illumination pulse signal with a randomly varying level width.
The precise illumination signal with randomly varying high and low level widths makes the intensity pulse signal non-periodic. The direct benefit of the aperiodicity of the pulse signal is that the spectrum of the signal is continuous and small in amplitude. At the same time, the PrISM high and low level signals are randomly changed, so there is no low frequency flicker problem that the low frequency PWM signal can be perceived by the human eye due to the slow change of its high and low level signals.
PSoC express helps users simplify and intuitively complete the development and design of high-bright LED color mixing applications, online debugging capabilities. The following is an example of Cypress's EZ-Color development board RGB-3261A, which describes how to use PSoC express for color mixing design and debugging.
A. Open the PSoC express software and create and name a new project.
B. Select the Triple Luxeon K2 color hybrid drive from the High Brightness LED in the Output Drives list and drag it to the workspace. After being released to the workspace, PSoC Express will pop up an Add Output Drive window. At this time, after inputting the drive ColorMixer as the HB LED driver name, click "ok".
C. When the HBLED window appears, select “Thermistor Temporary Sensor†from the associated temperature sensor list.
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Wire harness & Cable assembly
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