Hi, I complied your code for NRF51822 chip but I am getting the following errors at compile Arduino: 1.8.11 (Mac OS X), Board: "MyBoardNRF5 nRF51822, 16 kB RAM, 256 kB flash (xxaa), None, Crystal Oscillator" WARNING: library LIS2DW12-master claims to run on stm32, avr, sam architecture(s) and may be incompatible with your current board which runs on nRF5 architecture(s). /Users/puneit/Google Drive/MySensor/NRF51822/doorsensor/doorsensor.ino: In function 'void board_Init()': doorsensor:417:3: error: 'NRF_NFCT' was not declared in this scope NRF_NFCT->TASKS_DISABLE = 1; ^ doorsensor:419:13: error: 'struct NRF_UICR_Type' has no member named 'NFCPINS' NRF_UICR->NFCPINS = 0; ^ doorsensor:421:3: error: 'NRF_SAADC' was not declared in this scope NRF_SAADC ->ENABLE = 0; ^ doorsensor:422:3: error: 'NRF_PWM0' was not declared in this scope NRF_PWM0 ->ENABLE = 0; ^ doorsensor:423:3: error: 'NRF_PWM1' was not declared in this scope NRF_PWM1 ->ENABLE = 0; ^ doorsensor:424:3: error: 'NRF_PWM2' was not declared in this scope NRF_PWM2 ->ENABLE = 0; ^ doorsensor:425:3: error: 'NRF_TWIM1' was not declared in this scope NRF_TWIM1 ->ENABLE = 0; ^ doorsensor:426:3: error: 'NRF_TWIS1' was not declared in this scope NRF_TWIS1 ->ENABLE = 0; ^ Multiple libraries were found for "Wire.h" Used: /Users/puneit/Library/Arduino15/packages/sandeepmistry/hardware/nRF5/0.6.0/libraries/Wire Not used: /Users/puneit/Documents/Arduino/libraries/Wire Multiple libraries were found for "SPI.h" Used: /Users/puneit/Library/Arduino15/packages/sandeepmistry/hardware/nRF5/0.6.0/libraries/SPI Not used: /Users/puneit/Documents/Arduino/libraries/SPI exit status 1 'NRF_NFCT' was not declared in this scope Invalid library found in /Users/puneit/Documents/Arduino/libraries/ESP8266SdFat: no headers files (.h) found in /Users/puneit/Documents/Arduino/libraries/ESP8266SdFat Invalid library found in /Users/puneit/Documents/Arduino/libraries/SoftwareSerial: no headers files (.h) found in /Users/puneit/Documents/Arduino/libraries/SoftwareSerial Invalid library found in /Users/puneit/Documents/Arduino/libraries/ArduinoHwNRF5-master: no headers files (.h) found in /Users/puneit/Documents/Arduino/libraries/ArduinoHwNRF5-master Invalid library found in /Users/puneit/Documents/Arduino/libraries/arduino-nRF5-master: no headers files (.h) found in /Users/puneit/Documents/Arduino/libraries/arduino-nRF5-master Invalid library found in /Users/puneit/Documents/Arduino/libraries/ArduinoBoards-master: no headers files (.h) found in /Users/puneit/Documents/Arduino/libraries/ArduinoBoards-master This report would have more information with "Show verbose output during compilation" option enabled in File -> Preferences.