| CAccelSensorClass | |
| CAesmClass | |
| CApplicationSensorClass | |
| CAudioClass | Audio Library Class Definitions | 
| CCameraClass | [en] The class to control Spresense Camera.  [ja] SpresenseのCamera機能を制御するためのクラス。  | 
| CCamImage | [en] The class which is to control Image from Camera.  [ja] Cameraから得られる画像データを利用するためのクラス。  | 
| CDNNRT | |
| CDNNVariable | |
| CEEPROMClass | |
| CEEPtr | |
| CEERef | |
| CeMMCClass | The eMMC class provides functions for accessing the eMMC and manipulating its files and directories. Also, this class also provides the USB Mass storage function | 
| CFFTClass | |
| CFile | Allows for reading from and writing to individual files on the File System | 
| CFlashClass | The Flash class provides functions for accessing the flash and manipulating its files and directories.  | 
| CFrontEnd | FrontEnd Class Definitions | 
| CGnssPositionData | |
| CIIRClass | Biquad IIR filter class | 
| CImgBuff | [en] Camera Image memory management class. This is internal class.  [ja] Cameraのイメージメモリ管理用クラス。内部利用Class。  | 
| CLowPowerClass | This provides the features fo the power saving | 
| CLTEAccessProvider | [en] The class to construct a path for communication between the LTE network and modem.  [ja] LTEネットワークとモデム間で通信するための通信経路を構築するクラス。  | 
| CLTEClient | [en] Create a client that can connect to a specific Internet IP address and port.  [ja] 特定のインターネットIPアドレスとポートに接続可能なクライアントを作成します。  | 
| CLTECore | [en] Core class of LTE library. This is internal class.  [ja] LTEライブラリのCoreクラス。内部利用Class。  | 
| CLTEModemVerification | [en] The class to get modem information.  [ja] モデムの情報を取得するクラス。  | 
| CLTEScanNetworks | [en] The class to get LTE network information. [ja] LTEネットワークの情報を取得するためのクラス。  | 
| CLTETLSClient | [en] Create a secure client that can connect to a specific Internet IP address and port.  [ja] 特定のインターネットIPアドレスとポートに接続可能なセキュアーなクライアントを作成します。  | 
| CLTEUDP | [en] This class can send and receive UDP packets to a specific Internet IP address and port.  [ja] 特定のインターネットIPアドレスとポートに対してUDPパケットの送受信ができます。  | 
| CLTEUDPBuffer | [en] UDP packet memory management class. This is internal use class.  [ja] UDPパケットメモリ管理用クラス。内部利用Class。  | 
| CMediaPlayer | MediaPlayer Class Definitions | 
| CMediaRecorder | MediaRecorder Class Definitions | 
| CMemoryUtilClass | MemoryManager Library Class Definitions | 
| CMPClass | This is the interface for MP (Multi-Processor) | 
| CMPMutex | This is the interface for MP Mutex | 
| CNetPBM | |
| COutputMixer | OutputMixer Class Definitions | 
| CRingBuff | |
| CRtcClass | This is the interface to the RTC Hardware | 
| CRtcTime | RTC time definitions | 
| CSDClass | The SD class provides functions for accessing the SD card and manipulating its files and directories. Also, this class also provides the USB Mass storage function | 
| CSensorClient | |
| CSensorClientClass | Sensor Library Class Definitions | 
| CSensorManagerClass | |
| CServo | |
| CSoftwareSerial | SoftwareSerial controller | 
| CSpGnss | GNSS controller | 
| CSpGnssTime | Time acquired from the satellite at the time of positioning | 
| CSPIClass | SPI controller | 
| CSPISettings | SPI settings | 
| CSpNavData | GNSS positioning data | 
| CSpSatellite | Satellite information using positioning | 
| CStepCountReaderClass | |
| CStorageClass | The Storage class provides functions for accessing the storage manipulating its files and directories.  | 
| CtlsClientContext_s | |
| CTwoWire | |
| CWatchdogClass | Watchdog controller |