Ambient 21 Click

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-response photodiode. These ADCs convert the photodiode currents into a digital output representing the irradiance measured on each channel. Ambient 21 Click communicates with an 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

Pinout diagram

This table shows how the pinout on Ambient 21 Click corresponds to the pinout on the mikroBUS™ socket (the latter shown in the two middle columns).

Notes	Pin					Pin	Notes
	NC	1	AN	PWM	16	NC
	NC	2	RST	INT	15	INT	Interrupt
	NC	3	CS	RX	14	NC
	NC	4	SCK	TX	13	NC
	NC	5	MISO	SCL	12	SCL	I2C Clock
	NC	6	MOSI	SDA	11	SDA	I2C Data
Power Supply	3.3V	7	3.3V	5V	10	NC
Ground	GND	8	GND	GND	9	GND	Ground

Onboard settings and indicators

Ambient 21 Click electrical specifications

Software Support

We provide a library for the Ambient 21 Click as well as a demo application (example), developed using Mikroe compilers. The demo can run on all the main Mikroe development boards.

Package can be downloaded/installed directly from NECTO Studio Package Manager (recommended), downloaded from our LibStock™ or found on Mikroe github account.

Library Description

This library contains API for Ambient 21 Click driver.

Key functions

• ambient21_get_int_pin This function returns the INT pin logic state.

• ambient21_read_raw_data This function checks if the data is ready and then reads the raw ADC data from two channels.

• ambient21_measure_light_level This function reads the raw ADC data from two channels and then measures the light level in lux based on those readings.

Example Description

This example demonstrates the use of Ambient 21 Click board™ by measuring the ambient light level in Lux.

void application_task ( void ) 
 { 
     uint16_t lux; 
     if ( !ambient21_get_int_pin ( &ambient21 ) ) 
     { 
         if ( AMBIENT21_OK == ambient21_measure_light_level ( &ambient21, &lux ) ) 
         { 
             log_printf ( &logger, " Ambient light level [Lux]: %urnn", lux ); 
         } 
     } 
 }

The full application code, and ready-to-use projects can be installed directly from NECTO Studio Package Manager(recommended), downloaded from our LibStock™ or found on Mikroe github account.

Other Mikroe Libraries used in the example:

• MikroSDK.Board
• MikroSDK.Log
• Click.Ambient21

Additional notes and informations

Depending on the development board you are using, you may need USB UART click, USB UART 2 Click or RS232 Click to connect to your PC, for development systems with no UART to USB interface available on the board. A UART terminal is available in all Mikroe compilers.

mikroSDK

This Click board™ is supported by a mikroSDK – Mikroe Software Development Kit. To ensure proper operation of mikroSDK compliant Click board™ demo applications, mikroSDK should be downloaded from LibStock and installed for the compiler you are using.

For more information about mikroSDK, visit the official page.