Open Health Band Firmware

Firmware for Open Health Band use main bracnh to work with cyclist app

Description

This repository regroups all the firmware and tests which run on Open Health Band.
For hardware plans and schematics see movuino/OpenHealthBand. For the web BLE GUI see movuino/OpenHealthBandVisualization

Getting Started

Dependencies

All OHB firmware make use of Arduino Integrated Development Environment.

Board definition

• Open the Arduino IDE
• Navigate to Preferences
• Add https://movuino.github.io/movuino-board-index/package_movuino_index.json as an 'Additional Board Manager URL'.

Libraries

The following librairies are required to build the firmware and tests:

• MPU9250 by hideakitai : place the version provided in Arduino Librairies
• Adafruit Bluefruit nRF52 : version 0.21.0
• Max86141 : version 1.0.4

Those libraries are all available in the Arduino Library manager except MPU9250 that we should add in Arduino Librairie.

Services and Characteristics for BLE

The following services and characteristics use Notification properties :

Error Service & characteristic

The Error Characteristic allows to send boolean errors from IMU, PPG. Thus, when error is 0 data is detected else 1.

	ErrorService	ErrorCharacteristic
UUID	0x1200	0x1201

2 bytes	byte 1	byte 2
ErrorCharacteristic	errorIMU	errorPPG86

IMU Service & characteristics

With the IMU Service and characteristics, data from accelerometer, gyrometer and magnetometer can be send by BLE.

	IMUService	AccCharacteristic	GyroCharacteristic	MagCharacteristic
UUID	0x1101	0x1102	0x1103	0x1104

11 bytes	4 bytes (0-3)	2 bytes (5-6)	2 bytes (7-8)	2 bytes (9-10)
AccCharacteristic	timestamp	AccX	AccY	AccZ
GyroCharacteristic	timestamp	GX	GY	GZ

10 bytes	4 bytes (0-3)	2 bytes (4-5)	2 bytes (6-7)	2 bytes (8-9)
MagCharacteristic	timestamp	MX	MY	MZ

PPG Max 86140 - 86141 Service & Characteristics

With the PPG Service and characteristics, data from PPG can be send by BLE. We can have these type of sensor configuartions :

• 1 PD - 2 LEDS

ledSeq1A_PPG1Characteristic1 = characteristic for data taken from photo-diode

	PPG86Service	ledSeq1A_PPG1Characteristic1	SNR1_2PPG1Characteristic1
UUID	0x1300	0x1301	0x1315

20 bytes	4 bytes (0-3)	4 bytes (4-7)	4 bytes (8-11)	4 bytes (12-15)	4 bytes (16-19)
ledSeq1A_PPG1Characteristic1	timestamp	sample 1	sample 2	sample 3	sample 4

4 bytes	4 bytes (0-3)
SNR1_2PPG1Characteristic1	SNR photo-diode 1

• 2 PDs - 1 LED

ledSeq1A_PPG1Characteristic2 = characteristic for data taken from photo-diode 1 ledSeq1A_PPG2Characteristic2 = characteristic for data taken from photo-diode 2

	PPG86Service	ledSeq1A_PPG1Characteristic2	ledSeq1A_PPG2Characteristic2	SNR1_2PPG1Characteristic2	SNR2_2PPG2Characteristic2
UUID	0x1300	0x1305	0x1307	0x1313	0x1314

20 bytes	4 bytes (0-3)	4 bytes (4-7)	4 bytes (8-11)
ledSeq1A_PPG1Characteristic2	timestamp	sample 1	sample 2
ledSeq1A_PPG2Characteristic2	timestamp	sample 1	sample 2

4 bytes	4 bytes (0-3)
SNR1_2PPG1Characteristic2	SNR photo-diode 1
SNR2_2PPG1Characteristic2	SNR photo-diode 2

• 2 PDs - 3 LEDs

ledSeq1A_PPG1Characteristic3 = characteristic for data taken from photo-diode 1 ledSeq1A_PPG2Characteristic3 = characteristic for data taken from photo-diode 2

	PPG86Service	ledSeq1A_PPG1Characteristic3	ledSeq1A_PPG2Characteristic3	SNR1_2PPG1Characteristic3	SNR2_2PPG2Characteristic3
UUID	0x1300	0x1309	0x1311	0x1317	0x1318

12 bytes	4 bytes (0-3)	4 bytes (4-7)	4 bytes (8-11)
ledSeq1A_PPG1Characteristic3	timestamp	sample 1	sample 2
ledSeq1A_PPG2Characteristic3	timestamp	sample 1	sample 2

4 bytes	4 bytes (0-3)
SNR1_2PPG1Characteristic3	SNR photo-diode 1
SNR2_2PPG1Characteristic3	SNR photo-diode 2

HeartRate Service & characteristics

In order to detect the peripheral in the Bluetooth Settings for iPhone, we added the HeartRate taken from Adafruit Bluefruit nrf52 librairies --> Peripheral. However, it is not sent by BLE.

The following service and characteristics use READ and Write properties :

Start_Stop Service & characteristics

With the Start_Stop Service and characteristics, central BLE can decide when to start or stop data transfert and change leds intensity, sample rate and sample average.

	Start_StopService	StartCharacteristic	intensityLedsCharacteristic	smplRateCharacteristic	smplAvgCharacteristic
UUID	0x1400	0x1401	0x1402	0x1403	0x1404

1 byte	1 byte (0)
StartCharacteristic	1 (start) or 2 (stop)
intensityLedsCharacteristic	leds intensity
smplRateCharacteristic	PPG sample rate
smplAvgCharacteristic	PPG sample average

Values	leds intensity
0 - 255	leds off (min value) - leds on (max value)

Values (integer)	PPG sample rate (Hz)
0	25
1	50
2	84
3	100
4	200
5	400
14	128
15	256
16	512

Values (integer)	PPG sample average (Hz)
0	1
1	2
2	4
3	8
4	16
5	32
6	64

Use

• Choose your PPG sensor type (PDLEDs, PDsLED or PDsLEDs) by activating the #define

• To read data from PPG, IMU activated the #define from peripheral and central

• To read data on Serial Monitor or send by BLE activate the #define from peripheral

Documentation

Documentation for the project is available at movuino.github.io/OpenHealthBandFirmware or in the /docs folder.

• How to burn the bootloader
• OHB BLE protocol

Integration

OHB firmware can integrate with the Open Health Band Visualization project which provide real time monitoring of the OHB sensors in a web browser.