HOW DOES IT WORK?

Oximeter 5 Click as its foundation uses the MAX30102, a high-sensitivity pulse oximeter and heart-rate sensor from Maxim Integrated, now part of Analog Devices. The MAX30102 integrates Red and IR LEDs, with 660nm red and 880nm IR wavelengths, to modulate LED pulses for oxygen saturation (SpO2) and heart rate measurements. The LED pulse width can be programmed to allow the algorithm to optimize SpO2 and HR accuracy and power consumption based on use cases.

The SpO2 subsystem of the MAX30102 contains ambient light cancellation (ALC), a continuous-time oversampling sigma-delta ADC with 18-bit resolution, and a proprietary discrete-time filter. The ALC has an internal Track/Hold circuit to cancel ambient light and increase the effective dynamic range. The MAX30102 also has an on-chip temperature sensor with an inherent resolution of 0.0625°C for calibrating the temperature dependence of the SpO2 subsystem.

The MAX30102 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, providing a 1.8V out of both 5V and 3.3V mikroBUS™ power rails. Also, it can be shut down through software with zero standby current, allowing the power rails to remain powered at all times.

Oximeter 5 Click communicates with MCU using the standard I2C 2-Wire interface with a maximum clock frequency of 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 and SN74LVC1T45 voltage-level translators. The I2C interface bus lines are routed to the voltage-level translators allowing this Click board™ to work with both 3.3V and 5V MCUs properly. Also, it uses an interrupt pin, the INT pin of the mikroBUS™ socket, used for when an interrupt occurs, after the power is established, to alert the system that the MAX30102 is ready for operation.

This 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 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.