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Service + Characteristic Setup Code Analysis

1. The first thing to do is to call .begin() on the BLEService (hrms above). Since the UUID is set in the object declaration

at the top of the sketch, there is normally nothing else to do with the BLEService instance.

// a BLECharacteristic will cause it to be added to the last BLEService that

// was 'begin()'ed!

// Configure the Heart Rate Measurement characteristic

// See: https://www.bluetooth.com/specifications/gatt/viewer?attributeXmlFile=org.bluetooth.characteristic.heart_rate_measurement.xml

// Permission = Notify

// Min Len = 1

// Max Len = 8

// B0 = UINT8 - Flag (MANDATORY)

// b5:7 = Reserved

// b4 = RR-Internal (0 = Not present, 1 = Present)

// b3 = Energy expended status (0 = Not present, 1 = Present)

// b1:2 = Sensor contact status (0+1 = Not supported, 2 = Supported but contact not detected, 3 = Supported and detected)

// b0 = Value format (0 = UINT8, 1 = UINT16)

// B1 = UINT8 - 8-bit heart rate measurement value in BPM

// B2:3 = UINT16 - 16-bit heart rate measurement value in BPM

// B4:5 = UINT16 - Energy expended in joules

// B6:7 = UINT16 - RR Internal (1/1024 second resolution)

hrmc.setProperties(CHR_PROPS_NOTIFY);

hrmc.setPermission(SECMODE_OPEN, SECMODE_NO_ACCESS);

hrmc.setFixedLen(2);

hrmc.setCccdWriteCallback(cccd_callback); // Optionally capture CCCD updates

hrmc.begin();

uint8_t hrmdata[2] = { 0b00000110, 0x40 }; // Set the characteristic to use 8-bit values, with the sensor connected and detected

hrmc.notify(hrmdata, 2); // Use .notify instead of .write!

// Configure the Body Sensor Location characteristic

// See: https://www.bluetooth.com/specifications/gatt/viewer?attributeXmlFile=org.bluetooth.characteristic.body_sensor_location.xml

// Permission = Read

// Min Len = 1

// Max Len = 1

// B0 = UINT8 - Body Sensor Location

// 0 = Other

// 1 = Chest

// 2 = Wrist

// 3 = Finger

// 4 = Hand

// 5 = Ear Lobe

// 6 = Foot

// 7:255 = Reserved

bslc.setProperties(CHR_PROPS_READ);

bslc.setPermission(SECMODE_OPEN, SECMODE_NO_ACCESS);

bslc.setFixedLen(1);

bslc.begin();

bslc.write8(2); // Set the characteristic to 'Wrist' (2)

}

You MUST call .begin() on the BLEService before adding any BLECharacteristics. Any BLECharacteristic will

automatically be added to the last BLEService that was `begin()'ed!