The new optical heart rate sensing solution from Silicon Labs combines a low-power optical sensor module with an energy-friendly EFM32 Gecko microcontroller running a proprietary heart rate monitoring (HRM) algorithm. The module is capable of accuratly sensing weak blood flow signals on the wrist rivalling traditional chest strap designs.

The Si1144 optical module uses a single green LED, which allows it to be housed in a tiny package of only 2.9 mm x 4.9 mm. Besides the LED, the module integrates an optical sensor, LED drivers for up to two external LEDs, an analog-to-digital converter (ADC), control logic and an I²C digital interface. It can be paired with a Pearl Gecko MCU containing a DSP-enabled ARM Cortex-M4 core for low-power, high-performance designs or with a Cortex M3-based Jade Gecko MCU for simpler, cost-sensitive designs. A choice of two algorithms for either static HRM or dynamic (motion-compensated) HRM using data from an external accelerometer is available.