HOW DOES IT WORK?

Ambient 21 Click is based on the TSL2591, a high-sensitivity light-to-digital converter from ams AG. The TSL2591 provides ambient light sensing (ALS) that approximates the human eye response to light intensity under various lighting conditions and through different attenuation materials. It has a flexible and wide operating range of up to 88klx with the highest sensitivity of 188μlx, even when mounted behind dark glass. This sensor comes in a UV-rejection package enabling its operation in IR light environments making this board most suitable for various brightness control functions, helping to reduce power consumption.

The TSL2591 contains two integrating analog-to-digital converters (ADC) that integrate currents from two photodiodes, one broadband photodiode (visible plus infrared) and one infrared-responding photodiode. These ADCs convert the photodiode currents into a digital output representing the irradiance measured on each channel. Ambient 21 Click communicates with MCU using the standard I2C 2-Wire interface to read data and configure settings, supporting Standard Mode operation with a clock frequency of 100kHz and Fast Mode up to 400kHz.

Integration of both channels co-occurs. Upon completion of the conversion cycle, the conversion result is transferred to the appropriate channel data registers. The transfers are double-buffered to ensure that the integrity of the data is maintained. After the transfer, the device automatically begins the next integration cycle. This sensor also supports an interrupt feature, routed to the INT pin on the mikroBUS™ socket, that simplifies and improves system efficiency by eliminating the need to poll a sensor for a light intensity value. The purpose of the interrupt function is to detect a meaningful change in light intensity, where the user can define the concept of a significant change in light intensity and time or persistence. Users can define a threshold above and below the current light level, where an interrupt generates when the conversion value exceeds either of these limits.

This Click board™ can be operated only with a 3.3V logic voltage level. The board must perform appropriate logic voltage level conversion before using MCUs with different logic levels. However, the Click board™ comes equipped with a library containing functions and an example code that can be used as a reference for further development.

SPECIFICATIONS