Heart Rate 13 Click

How does it work?

Heart Rate 13 Click is based on the SFH 7074, a high-performance biomonitoring sensor from ams OSRAM, designed for precise and reliable vital sign monitoring. This sensor is optimized for photoplethysmography (PPG) applications, providing a strong and accurate optical signal while minimizing the effects of optical crosstalk through an integrated light barrier. Additionally, the SFH 7074 meets stringent ESD protection standards (1.5 kV acc. to ANSI/ESDA/JEDEC JS-001 HBM), ensuring robustness in various operating environments. Due to its advanced design, this sensor is widely used in digital diagnostic applications like wearable devices, fitness trackers, and medical diagnostic equipment, enabling accurate heart rate, oxygen saturation, and other biometric measurements.

Heart Rate 13 Click incorporates the ADPD1080, a photometric front-end from Analog Devices, to ensure optimal signal processing and high measurement accuracy. This front end is essential for handling the optical signals received from the SFH 7074, as it includes a 14-bit analog-to-digital converter (ADC) and a 20-bit burst accumulator, allowing precise digital conversion of the detected biometric data. The ADPD1080 controls the sensor's light-emitting diodes (LEDs), stimulating and capturing the reflected optical signals to generate accurate readings. A key advantage of this front-end is its built-in signal processing capabilities, which eliminate the need for external optical filters or DC cancellation circuits. It suppresses signal offset and reduces corruption caused by modulated interference, commonly introduced by ambient light sources, ensuring stable and reliable biometric measurements.

This Click board™ establishes communication with the host MCU through a standard I2C interface of the ADPD1080 operating at 1.8V. Additionally, it features two general-purpose I/O pins (IO0 and IO1), which are connected to the default mikroBUS™ socket's PWM and INT positions. These pins serve as interrupt sources and offer various clocking options, allowing for greater flexibility in application design and integration with different processing platforms.

The SFH 7074 operates at a 3.3V supply and requires no specific power-up sequence. However, the ADPD1080 photometric front-end requires a 1.8V supply for its analog and digital core to function correctly. To accommodate this requirement, Heart Rate 13 Click integrates a small low-dropout (LDO) voltage regulator, the BH18PB1WHFV, which converts the 3.3V mikroBUS™ power rail into a stable 1.8V supply, ensuring proper operation of the ADPD1080.

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. It also comes equipped with a library containing functions and example code that can be used as a reference for further development.

Specifications

Pinout diagram

This table shows how the pinout on Heart Rate 13 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	IO0	General-Purpose I/O 0
	NC	2	RST	INT	15	IO1	General-Purpose I/O 1
ID COMM	CS	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

Heart Rate 13 Click electrical specifications

Software Support

Heart Rate 13 Click demo application is developed using the NECTO Studio, ensuring compatibility with mikroSDK's open-source libraries and tools. Designed for plug-and-play implementation and testing, the demo is fully compatible with all development, starter, and mikromedia boards featuring a mikroBUS™ socket.

Example Description

This example demonstrates the use of Heart Rate 13 Click board by reading and displaying the PPG measurements which can be visualized on the SerialPlot application.

Key Functions

• heartrate13_cfg_setup Config Object Initialization function.
• heartrate13_init Initialization function.
• heartrate13_default_cfg Click Default Configuration function.
• heartrate13_get_pd_data This function waits for the data ready interrupt and then reads data from photodiodes PD1, PD2, and PD3.
• heartrate13_set_mode This function sets the device operating mode.
• heartrate13_sw_reset This function executes software reset of the device.

Application Init

Initializes the driver and performs the Click default configuration for heart rate measurement.

Application Task

Waits for the data ready interrupt, then reads the PPG measurements and displays it on the USB UART (SerialPlot).

Application Output

This Click board can be interfaced and monitored in two ways:

• Application Output - Use the "Application Output" window in Debug mode for real-time data monitoring. Set it up properly by following this tutorial.
• UART Terminal - Monitor data via the UART Terminal using a USB to UART converter. For detailed instructions, check out this tutorial.

Additional Notes and Information

The complete application code and a ready-to-use project are available through the NECTO Studio Package Manager for direct installation in the NECTO Studio. The application code can also be found on the MIKROE GitHub account.