The CHIP src directory is structured as follows:
| File / Folder | Contents | 
|---|---|
| app | Application Layer -- Zigbee Cluster Library (ZCL) | 
| ble | BLE Layer -- Bluetooth Transport Protocol (BTP) | 
| controller | Controller API | 
| crypto | Cryptography libraries | 
| darwin | Darwin Framework (iOS and macOS) | 
| include | Public headers | 
| inet | Network Layer -- TCP and UDP endpoints | 
| lib | Core and Support libraries | 
| lwip | Lightweight IP adaptation (to third_party library) | 
| platform | Device Layer -- platform portability adaptations | 
| qrcodetool | QR code tool | 
| setup_payload | QR code setup data encode / decode library | 
| system | System Layer -- common APIs for mem, work, etc. | 
| test_driver | Framework for on-device testing | 
NFC Tag Reading is disabled by default because a paid Apple developer account is required to have it enabled. If you want to enable it and you have a paid Apple developer account, go to the CHIPTool iOS target and turn on Near Field Communication Tag Reading under the Capabilities tab.