Heart rate monitoring sensor lowers cost of heart rate measurement

Designed to reduce the cost and complexity of wrist-based heart rate monitoring (HRM) applications, the Si1144 has a low-power optical sensor module, paired with an EFM32 Gecko microcontroller running the company’s HRM algorithm.

It also has a green LED, LED drivers supporting up to two external LEDs, ADC, control logic and an I²C digital interface.

Wrist-based HRM technology is a more convenient, comfortable way to measure heart rate and rivals the accuracy of chest strap-based designs.

As well as cost and power consumption, the nature of complex motion combine to make wrist-based HRM a complicated design challenge, says the company. To address these challenges, the Si1144-AAGX HRM module senses weak blood flow signals on the wrist with what the company says is “exceptional performance, rivalling chest strap HRM designs”. There are two algorithms to support static HRM and optional dynamic (motion- compensated) HRM using data from an external accelerometer.

Pairing an optical module with a Pearl Gecko MCU containing a DSP-enabled ARM Cortex-M4 core targets low-power, high-performance designs; while a Cortex M3-based Jade Gecko MCU is for simpler, cost-sensitive designs.

To extend battery life, power consumption is less than 500nA standby current with 1.71 to 3.6 V supply voltage. The I²C serial communications with up to 3.4Mbit/s data rate.

It is supplied in a 10-lead 4.9 x 2.85 x 1.2mm LGA and is sampling now.


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