# BLE peripheral example

(See the README.md file in the upper level 'examples' directory for more information about examples.)

This example creates GATT server and then starts advertising, waiting to be connected to a GATT client.

It uses ESP32's Bluetooth controller and NimBLE stack based BLE host.

This example aims at understanding GATT database configuration, advertisement and SMP related NimBLE APIs.

It also demonstrates security features of NimBLE stack. SMP parameters like I/O capabilities of device, Bonding flag, MITM protection flag and Secure Connection only mode etc., can be configured through menuconfig options.

For RPA feature (currently Host based privacy feature is supported), use API `ble_hs_pvcy_rpa_config` to enable/disable host based privacy, `own_addr_type` needs to be set to `BLE_ADDR_RANDOM` to use this feature. Please include `ble_hs_pvcy.h` while using this API. As `ble_hs_pvcy_rpa_config` configures host privacy and sets address in controller, it is necessary to call this API after host-controller are synced (e.g. in `bleprph_on_sync` callback).

To test this demo, any BLE scanner app can be used.

A Python based utility `bleprph_test.py` is also provided (which will run as a BLE GATT Client) and can be used to test this example.

Note :

* Make sure to run `python -m pip install --user -r $IDF_PATH/requirements.txt -r $IDF_PATH/tools/ble/requirements.txt` to install the dependency packages needed.
* Currently this Python utility is only supported on Linux (BLE communication is via BLuez + DBus).

## How to use example

### Configure the project

```
idf.py menuconfig
```

* Set serial port under Serial Flasher Options.

* Select I/O capabilities of device from 'Example Configuration > I/O Capability', default is 'Just_works'.

* Enable/Disable other security related parameters 'Bonding, MITM option, secure connection(SM SC)' from 'Example Configuration'.

### Build and Flash

Build the project and flash it to the board, then run monitor tool to view serial output:

```
idf.py -p PORT flash monitor
```

(To exit the serial monitor, type ``Ctrl-]``.)

See the Getting Started Guide for full steps to configure and use ESP-IDF to build projects.

## Example Output

There is this console output when bleprph is connected and characteristic is read:

```

I (118) BTDM_INIT: BT controller compile version [fe7ced0]
I (118) system_api: Base MAC address is not set, read default base MAC address from BLK0 of EFUSE
W (128) phy_init: failed to load RF calibration data (0xffffffff), falling back to full calibration
I (268) phy: phy_version: 4100, 6fa5e27, Jan 25 2019, 17:02:06, 0, 2
I (508) NimBLE_BLE_PRPH: BLE Host Task Started
I (508) uart: queue free spaces: 8
GAP procedure initiated: stop advertising.
Device Address: xx:xx:xx:xx:xx:xx
GAP procedure initiated: advertise; disc_mode=2 adv_channel_map=0 own_addr_type=0 adv_filter_policy=0 adv_itvl_min=0 adv_itvl_max=0
connection established; status=0 handle=0 our_ota_addr_type=0 our_ota_addr=xx:xx:xx:xx:xx:xx our_id_addr_type=0 our_id_addr=xx:xx:xx:xx:xx:xx peer_ota_addr_type=1 peer_ota_addr=xx:xx:xx:xx:xx:xx peer_id_addr_type=1 peer_id_addr=xx:xx:xx:xx:xx:xx conn_itvl=39 conn_latency=0 supervision_timeout=500 encrypted=0 authenticated=0 bonded=0

connection updated; status=0 handle=0 our_ota_addr_type=0 our_ota_addr=xx:xx:xx:xx:xx:xx our_id_addr_type=0 our_id_addr=xx:xx:xx:xx:xx:xx peer_ota_addr_type=1 peer_ota_addr=xx:xx:xx:xx:xx:xx peer_id_addr_type=1 peer_id_addr=xx:xx:xx:xx:xx:xx conn_itvl=6 conn_latency=0 supervision_timeout=500 encrypted=0 authenticated=0 bonded=0

I (50888) NimBLE_BLE_PRPH: PASSKEY_ACTION_EVENT started

I (50888) NimBLE_BLE_PRPH: Passkey on device's display: xxxxxx
I (50888) NimBLE_BLE_PRPH: Accept or reject the passkey through console in this format -> key Y or key N
key Y
I (50898) NimBLE_BLE_PRPH: ble_sm_inject_io result: 0

encryption change event; status=0 handle=0 our_ota_addr_type=0 our_ota_addr=xx:xx:xx:xx:xx:xx our_id_addr_type=0 our_id_addr=xx:xx:xx:xx:xx:xx peer_ota_addr_type=1 peer_ota_addr=xx:xx:xx:xx:xx:xx peer_id_addr_type=1
peer_id_addr=xx:xx:xx:xx:xx:xx conn_itvl=6 conn_latency=0 supervision_timeout=500 encrypted=1 authenticated=1 bonded=1

connection updated; status=0 handle=0 our_ota_addr_type=0 our_ota_addr=xx:xx:xx:xx:xx:xx our_id_addr_type=0 our_id_addr=xx:xx:xx:xx:xx:xx
peer_ota_addr_type=1 peer_ota_addr=xx:xx:xx:xx:xx:xx peer_id_addr_type=1 peer_id_addr=xx:xx:xx:xx:xx:xx conn_itvl=39 conn_latency=0 supervision_timeout=500 encrypted=1 authenticated=1 bonded=1

```

## Running Python Utility

```
python bleprph_test.py
```

## Python Utility Output

This is this output seen on the python side on successful connection:

```
discovering adapter...
bluetooth adapter discovered
powering on adapter...
bluetooth adapter powered on

Started Discovery

Connecting to device...

Connected to device

Services

[dbus.String(u'00001801-0000-1000-8000-00805f9b34fb', variant_level=1), dbus.String(u'59462f12-9543-9999-12c8-58b459a2712d', variant_level=1)]

Characteristics retrieved

	Characteristic:  /org/bluez/hci0/dev_xx_xx_xx_xx_xx_xx/service000a/char000b
	Characteristic UUID:  5c3a659e-897e-45e1-b016-007107c96df6
	Value:  dbus.Array([dbus.Byte(45), dbus.Byte(244), dbus.Byte(81), dbus.Byte(88)], signature=dbus.Signature('y'))
	Properties: :  dbus.Array([dbus.String(u'read')], signature=dbus.Signature('s'), variant_level=1)

	Characteristic:  /org/bluez/hci0/dev_xx_xx_xx_xx_xx_xx/service000a/char000d
	Characteristic UUID:  5c3a659e-897e-45e1-b016-007107c96df7
	Value:  dbus.Array([dbus.Byte(0)], signature=dbus.Signature('y'))
	Properties: :  dbus.Array([dbus.String(u'read'), dbus.String(u'write')], signature=dbus.Signature('s'), variant_level=1)

	Characteristic:  /org/bluez/hci0/dev_xx_xx_xx_xx_xx_xx/service0006/char0007
	Characteristic UUID:  00002a05-0000-1000-8000-00805f9b34fb
	Value:  None
	Properties: :  dbus.Array([dbus.String(u'indicate')], signature=dbus.Signature('s'), variant_level=1)

Characteristics after write operation

	Characteristic: /org/bluez/hci0/dev_xx_xx_xx_xx_xx_xx/service000a/char000b
	Characteristic UUID:  5c3a659e-897e-45e1-b016-007107c96df6
	Value: dbus.Array([dbus.Byte(45), dbus.Byte(244), dbus.Byte(81), dbus.Byte(88)], signature=dbus.Signature('y'))
	Properties: :  dbus.Array([dbus.String(u'read')], signature=dbus.Signature('s'), variant_level=1)

	Characteristic: /org/bluez/hci0/dev_xx_xx_xx_xx_xx_xx/service000a/char000d
	Characteristic UUID:  5c3a659e-897e-45e1-b016-007107c96df7
	Value: dbus.Array([dbus.Byte(65)], signature=dbus.Signature('y'))
	Properties: :  dbus.Array([dbus.String(u'read'), dbus.String(u'write')], signature=dbus.Signature('s'), variant_level=1)

	Characteristic: /org/bluez/hci0/dev_xx_xx_xx_xx_xx_xx/service0006/char0007
	Characteristic UUID:  00002a05-0000-1000-8000-00805f9b34fb
	Value: None
	Properties: :  dbus.Array([dbus.String(u'indicate')], signature=dbus.Signature('s'), variant_level=1)

exiting from test...
disconnecting device...
device disconnected
powering off adapter...
bluetooth adapter powered off
```

## Note
* NVS support is not yet integrated to bonding. So, for now, bonding is not persistent across reboot.