Heart Rate 10 Click Board™

Product Code: MIKROE-4724

How Does The Heart Rate 10 Click Board™ Work? The Heart Rate 10 Click Board™ as its foundation uses the MAX86916, a multipurpose optical sensor with applications in Heart Rate (HR) monitoring and as a medical-grade pulse oximeter from Analog Devices. The MAX86916 integrates four LED drivers and BLUE, GREEN, RED, and INFRARED LEDs. The LED current can be programmed from 0mA to 150mA, and pulse width can be programmed from 70μs to 420μs to allow the algorithm to optimize data acquisition accuracy and power consumption based on use cases. Also, the MAX86916 includes a proximity function to save power and reduce visible light emission when the user's finger is not on the sensor. The receive path in the MAX86916 is composed of an ambient-light-cancellation (ALC) circuit, a continuous-time sigma-delta ADC, and a proprietary digital filter that rejects slow-changing ambient light including 100Hz/120Hz interference from artificial lights. The ALC is designed to cancel ambient-light-generated photodiode current up to 200μA, allowing the sensor to work in high ambient light conditions.

When the ambient light cancellation function reaches its maximum limit, due to overflow from strong ambient light, the output of the ADC is affected, and the Ambient Light Cancellation Overflow interrupt, labelled as INT and routed on the INT pin of the mikroBUS™ socket, is generated to detect this condition. The MAX86916 does not require a specific Power-Up sequence but requires a supply voltage of 1.8V to work correctly. Therefore, a small regulating LDO is used, the MAX8511 from Analog Devices, providing a 1.8V out of both 5V and 3.3V mikroBUS™ rails. The Heart Rate 10 Click Board™ communicates with MCU using the standard I2C 2-Wire interface with a maximum clock frequency of up to 400kHz. It is fully adjustable through software registers, and the digital output data is stored in a 32-deep FIFO within the device. Since the sensor for operation requires a power supply of 1.8V, this Click board™ also features the PCA9306 voltage-level translator from Texas Instruments. The I2C interface bus lines are routed to the dual bidirectional voltage-level translator, allowing this Click board™ to work with both 3.3V and 5V MCUs properly. The Heart Rate 10 Click Board™ can operate with both 3.3V and 5V logic voltage levels selected via the VCC SEL jumper. This way, it is allowed for both 3.3V and 5V capable MCUs to use the I2C communication lines properly. However, the Click board™ comes equipped with a library containing easy-to-use functions and an example code that can be used, as a reference, for further development. SPECIFICATIONS Type Biometrics,Heart Rate Applications The Heart Rate 10 Click Board™ can be used for optical pulse oximetry and heart-rate detection applications. On-board modules MAX86916 - multipurpose optical sensor with applications in Heart Rate (HR) monitoring and as a medical-grade pulse oximeter from Maxim Integrated Key Features Low power consumption, ultra-low shutdoen current, optical-grade glass for long-term performance, reflective heart rate monitor, medical-grade pulse oximeter, bio-optical sensor platform, and more. Interface I2C Compatibility mikroBUS Click board size S (28.6 x 25.4 mm) Input Voltage 3.3V or 5V PINOUT DIAGRAM This table shows how the pinout of the Heart Rate 10 Click Board™ 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 5V Power Supply Ground GND 8 GND GND 9 GND Ground ONBOARD SETTINGS AND INDICATORS