// RH_Serial.h // // Copyright (C) 2014 Mike McCauley // $Id: RH_Serial.h,v 1.7 2014/06/24 02:40:12 mikem Exp $ // Works with any serial port. Tested with Arduino Mega connected to Serial1 // Also works with 3DR Radio V1.3 Telemetry kit (serial at 57600baud) #ifndef RH_Serial_h #define RH_Serial_h #include // Special characters #define STX 0x02 #define ETX 0x03 #define DLE 0x10 #define SYN 0x16 // Maximum message length (incgluding the headers) we are willing to support #define RH_SERIAL_MAX_PAYLOAD_LEN 64 // The length of the headers we add. // The headers are inside the payload and are therefore protected by the FCS #define RH_SERIAL_HEADER_LEN 4 // This is the maximum message length that can be supported by this library. // It is an arbitrary limit. // Can be pre-defined to a smaller size (to save SRAM) prior to including this header // Here we allow for 4 bytes of address and header and payload to be included in the 64 byte encryption limit. // the one byte payload length is not encrpyted #ifndef RH_SERIAL_MAX_MESSAGE_LEN #define RH_SERIAL_MAX_MESSAGE_LEN (RH_SERIAL_MAX_PAYLOAD_LEN - RH_SERIAL_HEADER_LEN) #endif class HardwareSerial; ///////////////////////////////////////////////////////////////////// /// \class RH_Serial RH_Serial.h /// \brief Driver to send and receive unaddressed, unreliable datagrams via a serial connection /// /// This class sends and received packetized messages over a serial connection. /// It can be used for point-to-point or multidrop, RS232, RS488 or other serial connections as /// supported by your controller hardware. /// It can also be used to communicate via radios with serial interfaces such as: /// - APC220 Radio Data Module http://www.dfrobot.com/image/data/TEL0005/APC220_Datasheet.pdf /// http://www.dfrobot.com/image/data/TEL0005/APC220_Datasheet.pdf /// - 3DR Telemetry Radio https://store.3drobotics.com/products/3dr-radio /// - HopeRF HM-TR module http://www.hoperf.com/upload/rf_app/HM-TRS.pdf /// - Others /// /// The packetised messages include message encapsulation, headers, a message payload and a checksum. /// /// \par Packet Format /// /// All messages sent and received by this RH_Serial Driver conform to this packet format: /// \code /// DLE /// STX /// TO Header (1 octet) /// FROM Header (1 octet) /// ID Header (1 octet) /// FLAGS Header (1 octet) /// Message payload (0 to 60 octets) /// DLE /// ETX /// Frame Check Sequence FCS CCITT CRC-16 (2 octets) /// \endcode /// /// If any of octets from TO header through to the end of the payload are a DLE, /// then they are preceded by a DLE (ie DLE stuffing). /// The FCS covers everything from the TO header to the ETX inclusive, but not any stuffed DLEs /// /// \par Physical connection /// /// The physical connection to your serial port will depend on the type of platform you are on. /// /// For example, many arduinos only support a single Serial port on pins 0 and 1, /// which is shared with the USB host connections. On such Arduinos, it is not possible to use both /// RH_Serial on the Serial port as well as using the Serial port for debugand other printing or communications. /// /// On Arduino Mega and Due, there are 4 serial ports: /// - Serial: this is the serial port connected to the USB interface and the programming host. /// - Serial1: on pins 18 (Tx) and 19 (Rx) /// - Serial2: on pins 16 (Tx) and 17 (Rx) /// - Serial3: on pins 14 (Tx) and 15 (Rx) /// /// On Uno32, there are 2 serial ports: /// - SerialUSB: this is the port for the USB host connection. /// - Serial1: on pins 39 (Rx) and 40 (Tx) /// /// On Maple and Flymaple, there are 4 serial ports: /// - SerialUSB: this is the port for the USB host connection. /// - Serial1: on pins 7 (Tx) and 8 (Rx) /// - Serial2: on pins 0 (Rx) and 1 (Tx) /// - Serial3: on pins 29 (Tx) and 30 (Rx) /// /// Note that it is necessary for you to select which Serial port your RF_Serial will use and pass it to the /// contructor. class RH_Serial : public RHGenericDriver { public: /// Constructor /// \param[in] serial Reference to the HardwareSerial port which will be used by this instance RH_Serial(HardwareSerial& serial); /// Initialise the Driver transport hardware and software. /// Make sure the Driver is properly configured before calling init(). /// \return true if initialisation succeeded. virtual bool init(); /// Tests whether a new message is available /// from the Driver. /// On most drivers, this will also put the Driver into RHModeRx mode until /// a message is actually received bythe transport, when it wil be returned to RHModeIdle. /// This can be called multiple times in a timeout loop /// \return true if a new, complete, error-free uncollected message is available to be retreived by recv() virtual bool available(); /// Turns the receiver on if it not already on. /// If there is a valid message available, copy it to buf and return true /// else return false. /// If a message is copied, *len is set to the length (Caution, 0 length messages are permitted). /// You should be sure to call this function frequently enough to not miss any messages /// It is recommended that you call it in your main loop. /// \param[in] buf Location to copy the received message /// \param[in,out] len Pointer to available space in buf. Set to the actual number of octets copied. /// \return true if a valid message was copied to buf virtual bool recv(uint8_t* buf, uint8_t* len); /// Waits until any previous transmit packet is finished being transmitted with waitPacketSent(). /// Then loads a message into the transmitter and starts the transmitter. Note that a message length /// of 0 is NOT permitted. /// \param[in] data Array of data to be sent /// \param[in] len Number of bytes of data to send (> 0) /// \return true if the message length was valid and it was correctly queued for transmit virtual bool send(const uint8_t* data, uint8_t len); /// Returns the maximum message length /// available in this Driver. /// \return The maximum legal message length virtual uint8_t maxMessageLength(); protected: /// \brief Defines different receiver states in teh receiver state machine typedef enum { RxStateInitialising = 0, ///< Before init() is called RxStateIdle, ///< Waiting for an STX RxStateDLE, ///< Waiting for the DLE after STX RxStateData, ///< Receiving data RxStateEscape, ///< Got a DLE while receiving data. RxStateWaitFCS1, ///< Got DLE ETX, waiting for first FCS octet RxStateWaitFCS2 ///< Waiting for second FCS octet } RxState; /// HAndle a character received from the serial port. IMplements /// the receiver state machine void handleRx(uint8_t ch); /// Empties the Rx buffer void clearRxBuf(); /// Adds a charater to the Rx buffer void appendRxBuf(uint8_t ch); /// Checks whether the Rx buffer contains valid data that is complete and uncorrupted /// Check the FCS, the TO address, and extracts the headers void validateRxBuf(); /// Sends a single data octet to the serial port. /// Implements DLE stuffing and keeps track of the senders FCS void txData(uint8_t ch); /// Reference to the HardwareSerial port we will use HardwareSerial& _serial; /// The current state of the Rx state machine RxState _rxState; /// Progressive FCS calc (CCITT CRC-16 covering all received data (but not stuffed DLEs), plus trailing DLE, ETX) uint16_t _rxFcs; /// The received FCS at the end of the current message uint16_t _rxRecdFcs; /// The Rx buffer uint8_t _rxBuf[RH_SERIAL_MAX_PAYLOAD_LEN]; /// Current length of data in the Rx buffer uint8_t _rxBufLen; /// True if the data in the Rx buffer is value and uncorrupted and complete message is available for collection bool _rxBufValid; /// FCS for transmitted data uint16_t _txFcs; }; /// @example serial_reliable_datagram_client.pde /// @example serial_reliable_datagram_server.pde #endif