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