In a previous article we showed a small epaper module from Lilygo. This is an add-on module which includes a a 200ma battery, HMC5883L compass, BMA423 step counter, and RTC function.
Here is an image of the epaper module, the add on board fits
Here is a summary of the various sensors included
The HMC5883L is a surface-mount,multi-chip module designed for low-field magnetic sensingwith a digital interface for applications such as low-cost compassing and magnetometry.
12-Bit ADC Coupled with Low Noise AMR Sensors Achieves 5 milli-gauss Resolution in ±8 Gauss Fields
Low Voltage Operations (2.16 to 3.6V)and Low Power Consumption (100 μA)
Wide Magnetic Field Range(+/-8Oe)
Fast 160Hz Maximum Output Rate
The BMA423 is an ultra-small, triaxial, low-g acceleration sensor with digital interfaces, aiming for low-power consumer electronics applications.
Featuring 12 bit digital resolution and embedded intelligence, the BMA423 allows low-noise measurement of accelerations in 3 perpendicular and thus senses wrist tilt, tab/double tab and enables plug ’n’ play step counting especially in wearable devices.
Step-counting in wearable devices
Wake up display on wrist tilt
Low power user interaction by tab/double tab
Advanced gesture recognition
Advanced power management for mobile devices
Tilt compensation for electronic compass
The PCF8563 is a CMOS Real-Time Clock (RTC) and calendar optimized for low power consumption. A programmable clock output, interrupt output, and voltage-low detector are also provided. All addresses and data are transferred serially via a two-line bidirectional I²C-bus.
Maximum bus speed is 400 kbit/s. The register address is incremented automatically after each written or read data byte.
Provides year, month, day, weekday, hours, minutes, and seconds based on a 32.768 kHz quartz crystal
Clock operating voltage: 1.0 V to 5.5 V at room temperature
Programmable clock output for peripheral devices (32.768 kHz, 1.024 kHz, 32 Hz, and 1 Hz)
Alarm and timer functions
Integrated oscillator capacitor
Internal Power-On Reset (POR)
I²C-bus target address: read A3h and write A2h
Open-drain interrupt pin
There are Arduino libraries and examples available from the github links at the bottom of this article
This module costs around £11 from Aliexpress