Radioland BLE beacon module datasheet:

https://www.renhotecic.com/image/download/pdf/2020031603025251822beacon.pdf

can be reprogrammed with Arduino IDE and ST Link V2 to special remote button application.

SWDIO -> SWDIO

SWCLK -> SWCLK

3.3V -> BAT+

GND -> BAT-

3D printed cover for BLE module:

Arduino IDE libraries for NRF51822 and instructions can be found from:

https://github.com/sandeepmistry/arduino-nRF5

Nrf51822 Bluetooth low energy stack (Softdevice) version S130 is required to download and flash to device before BLE application software can be programmed :

Selecting a SoftDevice

SoftDevices contain the BLE stack and housekeeping, and must be downloaded once before a sketch using BLE can be loaded. The SD consumes ~5k of Ram + some extra based on actual BLE configuration.

SoftDevice S130 v2.0.1 supports Revision 3 of nRF51 in peripheral and central role. It is 108k in size.

Flashing a SoftDevice

cd <SKETCHBOOK>, where <SKETCHBOOK> is your Arduino Sketch folder:

OS X: ~/Documents/Arduino
Linux: ~/Arduino
Windows: ~/Documents/Arduino

Create the following directories: tools/nRF5FlashSoftDevice/tool/
Download nRF5FlashSoftDevice.jar to <SKETCHBOOK>/tools/nRF5FlashSoftDevice/tool/
Restart the Arduino IDE
Select your nRF board from the Tools -> Board menu
Select a SoftDevice from the Tools -> "SoftDevice: " menu
Select a Programmer (J-Link, ST-Link V2, or CMSIS-DAP) from the Tools -> "Programmer: " menu
Select Tools -> nRF5 Flash SoftDevice
Read license agreement
Click "Accept" to accept license and continue, or "Decline" to decline and abort
If accepted, SoftDevice binary will be flashed to the board

There are some examples in

Arduino BLEPeripheral library:

https://github.com/sandeepmistry/arduino-BLEPeripheral

My own Arduino projects for NRF51822 can be downloaded from:

https://github.com/joukohak/arduino-nrf51

The project real time clock button is nrf51822_sensor_rtc and it requires to modify delay.h and delay.c in Sandeep Mistry's nRF51 library, because it is using nRF51822 device RTC1 counter, that is also used in Sandeep's library ( millis() and delay() ).

With nRF Connect Android application nrf51822_sensor_rtc project features can verified:

Services and Characteristics defined in Arduino code:

BLEService mainBleService("c83e0fa6-f5b7-473a-a2a2-3957117a2f58");

BLEUnsignedIntCharacteristic sensorCharacteristic("8afc0cf0-19bf-4bd2-9413-6e7259765edf", BLERead | BLEWrite | BLENotify);
BLEService batteryService("180F");
BLEUnsignedCharCharacteristic batteryLevelCharacteristic("2A19", BLERead);

Can be verified on nRF Connect application: - battery level is actually 20x mV instead % - sensorCharacteristic when button pressed shows 32 bit (4 bytes) data including: - seconds,minutes,hours and button counter value(byte)