Wearable - Bluetooth Sleep and Activity Tracker

Example bluetooth wearable code to track sleep and activity using the nRF52832 and LIS3DH accelerometer.

This is functional code that logs average intensity data once a minute. Logged data is downloaded over a bluetooth connection to a phone or computer for analysis. This has been tested against the very popular Mi Band 3 and has shown to be nearly identical.

Depending on the hardware, this will run for 3 - 5 months on a 2032 coin cell.

I've recently changed from a FIFO driven interrupt to timer based reading of accelerometer data after finding an intermittent bug that prevented the SoC from sleeping properly. There's some data in the Errata about this and I hope to have that worked out eventually. However, the difference in power draw is negligible.

I'm currently working on a Zephyr RTOS version of this project using the nRF Connect SDK and will add it to the repository when completed.

An example Web-Bluetooth application is provided (web folder).

A common method for calculating sleep stage:

intensity under 20 is considered sitting / low activity
more than 5 minutes of intensity under 5-10 can be considered entering sleep
more than 15 minutes of uninterrupted sleep is considered deep sleep

Hardware Setup

The accelerometer pin definitions are set in the custom_board.h file in the board directory.

Firmware Functionality

On initial startup the device will beging to advertise once a second. The accelerometer will be put into sleep mode and will not record activity until a bluetooth connection has been established and the time has been set. Once the time has been set, a rolling buffer will maintain 48 hours worth of activity data.

Bluetooth Profile

Primary service characteristics

ID: Read Retrieves the unique device ID (Bluetooth Mac Address).
DATETIME: Write Used to set the date/time (seconds since 1970).
BATTERY: Read Retrieves the current battery level
ACTIVITY_REQ: Write Requests activity data from the datetime provided
ACTIVITY_DATA: Read/Notify Activity log data response.

Prerequisites

nRF-SDK version 17.1.0

Extract to a directory near root to avoid directory length issues when building

C:\nordic_semi\nRF5_SDK_17.1.0_ddde560

Segger Embedded Studio version 6.30

Add Global Macros under Tools -> Options

CMSIS_CONFIG_TOOL=C:\nordic_semi\nRF5_SDK_17.1.0_ddde560\external_tools\cmsisconfig\CMSIS_Configuration_Wizard.jar
nRF5SDK=C:\\nordic_semi\\nRF5_SDK_17.1.0_ddde560

GCC Toolchain

In order to build some bootloader libraries, gcc / make will need to be installed:

5.4-2016-q3-update of the GCC compiler toolchain for ARM

And make on windows:

MinGW

Install the msys packages
create a make.bat file in c:\mingw\bin

@echo off
"%~dp0mingw32-make.exe" %*

update the [nRFSDK]/components/toolchain/gcc/Makefile.windows

GNU_INSTALL_ROOT := C:/Program Files (x86)/GNU Tools ARM Embedded/5.4 2016q3/bin/
GNU_VERSION := 5.4.1
GNU_PREFIX := arm-none-eabi

nRFUtils (required)

nRF Connect (optional, but useful)

Notes

The debug and release projects have NRF_LOG_ENABLED set/unset in the sdk_config.h

lukevanhorn/wearable