“Today’s products have become very smart and connected to each other. Devices such as speakers, TVs, refrigerators, set-top boxes and smoke detectors are no longer just tools in a certain location-users can control them remotely or by voice wake-up. These devices are smarter than before, which means they also need smarter human-computer interaction interfaces.
Author: Allie Zhang
Today’s products have become very smart and connected to each other. Devices such as speakers, TVs, refrigerators, set-top boxes and smoke detectors are no longer just tools in a certain location-users can control them remotely or by voice wake-up. These devices are smarter than before, which means they also need smarter human-computer interaction interfaces.
The human-computer interaction interface can be diverse. The LED ring, LED matrix, or red-green-blue (RGB) LED lighting formed by various creative combinations of light-emitting diodes (LEDs) are currently popular human-computer interaction methods, especially By changing modes such as chasing or blinking, the flexibility and aesthetics of using LED as a human-machine interface is increased. Figure 1 shows some examples of patterns.
Figure 1: Example of LEDs used in human-machine interface
To have an extremely friendly human-machine interface, these elements are very important:
• Perfect color mixing, the color changes according to user requirements.
• Suitable LED brightness: not too dark during the day and not too bright at night.
• Beautiful dynamic effects, such as chasing or flashing.
• When the power source comes from a battery, the same brightness Display and high efficiency can also be achieved.
• Although at first glance this list is unwieldy, but in fact it only needs an excellent LED driver to achieve it easily. This LED driver needs to have the following functions:
• Ability to use suitable communication protocols, such as I2C, to drive multiple channels. The microcontroller (MCU) can communicate with the device and independently control each channel without consuming a large amount of general-purpose input/output GPIO pin resources.
• High-resolution pulse width modulation (PWM) control, used to change the brightness of the LED, but not too much visual experience of step changes.
• Very low quiescent current, and suitable power saving mode.
• The high-frequency pulse width modulation signal can avoid noise that can be discerned by the human ear, because many LED indicators are used with speakers.
Texas Instruments’ LP50xx series of multi-channel RGB LED drivers are shown in Figure 2, which is very suitable for this function.
Figure 2: Lp50xx series function block
These devices integrate a 12-bit PWM generator. Its working frequency is higher than the human discernible noise frequency, and the frequency of each channel is 29 kHz, which can realize stable and accurate color bending control and zero noise. Each channel provides independent color mixing and brightness control. With integrated power saving modes, these LED drivers can significantly reduce power consumption, thereby increasing the overall system efficiency in standby mode. The LP50xx series has 9,12,18,24,30,36 multiple options, which can meet the design requirements of insufficient LED configuration.
The LP50xx series can help you realize the seamless and smooth conversion effect of LED as a human-computer interaction interface, which is widely used in portable Electronic equipment, building automation and smart home appliances.