BLE – Bernd's development stuff

April 6, 2018 52 comments

ESP32 WiFi setup over BLE (ESP32 code)

Most small applications that we write have the WiFi credentials integrated in the code. But sometimes you do not want to have your WiFi credentials in the source code, specially if it is open source and maybe accessible as a repository on Github or Bitbucket. Having the WiFi credentials in the code is as well not practical if you sell your devices to others that need to setup the WiFi credentials according to their local network. There are several solutions

February 27, 2018 One comment

Initialize Bluetooth Serial and BLE server

If both BLE and Bluetooth are required to operate in the code, the initialization sequence seems to be critical. Complete initialization of a BLE server and then separate initialization of Bluetooth Serial didn’t work. The correct sequence seems to be

Init BLE device => BLEDevice::init(apName);
Init Bluetooth Serial => SerialBT.begin(apName);
Then do the rest of the BLE initialisation like
- create server
- add callbacks to server
- add characteristics
- start server
- start advertising

Init BLE device => BLEDevice::init(apName);

Init Bluetooth Serial => SerialBT.begin(apName);

Then do the rest of the BLE initialisation like

- create server

- add callbacks to server

- add characteristics

- start server

- start advertising

Here is a code extract that worked for me

void initBlueTooth() {
  // Initialize BLE
  BLEDevice::init(apName);
  BLEDevice::setPower(ESP_PWR_LVL_P7);

  SerialBT.begin(apName);

  // Create BLE Server
  pServer = BLEDevice::createServer();

// ...
// initialize BLE callbacks and characteristics
// ...

  // Start the service
  pService->start();

  // Start advertising
  pAdvertising = pServer->getAdvertising();

  pAdvertising->start();
}

void initBlueTooth() {

// Initialize BLE

BLEDevice::init(apName);

BLEDevice::setPower(ESP_PWR_LVL_P7);

SerialBT.begin(apName);

// Create BLE Server

pServer = BLEDevice::createServer();

// ...

// initialize BLE callbacks and characteristics

// ...

// Start the service

pService->start();

// Start advertising

pAdvertising = pServer->getAdvertising();

pAdvertising->start();

}

Full code example for the initialization can be found in this Github repo.

February 27, 2018 One comment

ESP32 Bluetooth Serial and BLE server running together

There is a new kid coming into the arduino-esp32 world. A Bluetooth Serial library that allows you to use Bluetooth (not BLE) like a serial port. This way you can connect the ESP32 over Bluetooth to an Android app like the Serial Bluetooth Terminal and use it as a serial in/out interface. The library is not yet in the arduino-esp32 repository, but I grabbed a preview from copercini’s repo. It is working fine, I could connect my Android tablet to my

February 15, 2018 Leave a comment

Deep-Sleep needs WiFi and Bluetooth switched OFF for low current consumption

rudi48 made some investigations regarding power saving during deep sleep here. Summary: To achieve maximum power saving during deep sleep it is necessary to switch off Bluetooth and WiFi before calling esp_deep_sleep_start(); Example:

#include <esp_wifi.h>
#include <esp_bt.h>
...
  esp_wifi_stop();
  esp_bt_controller_disable();
  esp_deep_sleep_start();

#include <esp_wifi.h>

#include <esp_bt.h>

...

esp_wifi_stop();

esp_bt_controller_disable();

esp_deep_sleep_start();

February 2, 2018 2 comments

ESP32 BLE server

I wanted to try out the BLE capabilities of the ESP32. I will not go into deep explanations how BLE works. Adafruit has a nice tutorial that explains details. To learn about BLE, check out the Introduction to Bluetooth Low Energy. As I have temperature and humidity sensors attached the logical step would be to set it up as an environment sensor. I checked the Bluetooth GATT services to find out if there is something matching defined. And there is

Bernd's development stuff

Software and hardware tips about Arduino, ESP chips and Android applications

Tag: BLE

ESP32 WiFi setup over BLE (ESP32 code)

Initialize Bluetooth Serial and BLE server

ESP32 Bluetooth Serial and BLE server running together

Deep-Sleep needs WiFi and Bluetooth switched OFF for low current consumption

ESP32 BLE server