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1 NAP Protocol 1.0

2 Version Version Date By Comment v JP Release version of NAP documentation. Table of Contents 1 Basic concepts Usage info Length byte Literal characters CT byte CS byte Configuration packet Data packet References List of abbreviations...11 Sensinode Proprietary and Confidential 2011 Sensinode Ltd. 2/12

3 This document specifies with examples how to use the serial NAP interface protocol to access the functionality provided by a radio module/chip with Sensinode NanoStack 2.0 Network Processor firmware [1]. The NAP protocol has been specifically designed to be used over UART or SPI. 1 Basic concepts NAP has been designed to be an easy-to-parse, low-overhead serial protocol that has enough flexibility and extendability for the NanoStack 2.0 Network Processors. Low complexity has been an important design goal so that the protocol can be efficiently parsed even on MCUs with very limited resources. The potentially limited serial port data rates have imposed the need for a very low overhead compared to the actual payload data. The NAP protocol defines two main types of packets Config for all configuration messages (request and replies) and status queries & answers Data for all data communication The high level packet format is described in Table 1. Byte N Name Length 'N' 'A' CT [Variable] [Variable] CS Table 1 - High level frame format. The interpretation of each field is described in the following chapters. 1.1 Usage info Before the Network Processor can be used to send/receive data packets it has to be configured properly. This is done by sending a single Config packet to the network processor. The type of the packet must be 0xC9 1 and there must be a single unsigned char as a parameter to the command. 1.2 Length byte The first byte of a NAP packet is always the length of the packet not including the length byte itself but including the last byte (CS). The byte is in normal host order i.e. the most significant bit 1 See Table 6 for detailed description of different Config packets. Sensinode Proprietary and Confidential 2011 Sensinode Ltd. 3/12

4 is first. The shortest possible NAP packet has a length of 5 bytes (Length=4, 'N', 'A', Config code, CS). 1.3 Literal characters The two bytes following the Length byte are ASCII characters 'N' and 'A' (0x4e and 0x41 respectively). The two bytes are static and present in all NAP packets. Wrong bytes will result in discarding of the packet at the Network Processor's NAP parser. 1.4 CT byte The CT byte is a bit field which has variable meaning depending on the first bit of the CT byte. The first bit defines if the packet is a Config or Data packet. If the bit is 0 the packet is a Data packet. Bit value 1 denotes a Config packet. The correct interpretation of bits 2-8 are described in paragraphs 2 and 3. Bit number Description Data/Config [Variable according to packet type] Table 2 - General CT byte bits for Configuration packet. Value Type Description D/C 0 or 1 Bit 0 = Data packet, 1 = Config packet Table 3 - D/C bit values. 1.5 CS byte Checksum byte is normal exclusive - OR calculation (XOR) from all bytes of the packet (excluding the CS byte itself). Network Processor's NAP parser will discard the packet if the CS doesn t match the calculated value. All the examples in the Chapters 2 and 3 have correct checksum bytes. 2 Configuration packet Configuration packets are used to SET/GET configuration of the network processor. All interchange of configuration information always consists of a REQUEST and a REPLY message Sensinode Proprietary and Confidential 2011 Sensinode Ltd. 4/12

5 i.e. every configuration packet of type REQUEST will be answered by a configuration packet of type REPLY. Also if the initial REQUEST has action type of GET the subsequent REPLY will have action type of GET as well and similarly for SET packets. A simple exchange of Config messages is shown in Fig. 1. For example in the first two messages the host MCU could request the status of the Network Processor network connectivity and receive the answer. In the second pair of messages the host MCU could for example change used radio channel. If the Network Processor's operating mode is Shutdown it transmits a Watchdog notify message (CT 0xE0) periodically with 500 ms interval. Fig. 1 A simple configuration message exchange: a GET REQUEST & REPLY pair followed by a SET REQUEST & REPLY pair. Table 4 and Table 5 describe the interpretation of the GET/SET and REQUEST/REPLY bits of the Config packet CT byte. Bit Description 1 (Config) GET/SET REQUEST/REPLY Config Code Table 4 - CT byte bits for Configuration packet. Sensinode Proprietary and Confidential 2011 Sensinode Ltd. 5/12

6 Field name Value Type Description GET/SET 0 or 1 Bit 0 = GET configuration info, 1 = SET configuration info REQUEST/REPLY 0 or 1 Bit 0 = Request, 1 = Reply Config Code See Table 6 Bit field See Table 6 Table 5 - Detailed CT byte bit description for Configuration packet. Sensinode Proprietary and Confidential 2011 Sensinode Ltd. 6/12

7 CT byte Description Parameters Notes 0x86 EUID request No - 0xA6 EUID - reply Yes Unsigned char array of 8 bytes in host byte order. 0x89 Get operation mode - request No 0xA9 Get operation mode reply Yes 0x00 for shutdown mode 0xC9 Set operation mode - request Yes 0x08 for active operation mode 0xE9 Set operation mode - reply Yes *0x09 for AES enabled mode (When AES with 0x09 is used, this byte must follow 16 bytes to set the used AES key) **NOTE: AES key is not returned if mode is requested. 0x8B Get ER status - request No - 0xAB Get ER status - reply Yes Description in table 7. 0xE0 Watchdog notify - reply Yes Length 'N' 'A' CT 0 (always) CS Length always 5 Table 6 - Config code (CT byte) descriptions. Field name Value Type Description Bit description of status byte: STATUS 0x0B Byte gateway type parent type mac type status MAC Any X bytes Mac type bits in status byte define the used address type. See Table 19 for bit usage. PARENT Any X bytes Parent type bits in status byte define the used address type. See Table 19 for bit usage. GATEWAY Gateway type bits in status byte define the used address type. See Any X bytes (NanoRouter) Table 19 for bit usage. HOP Any Byte Unsigned 8 bit variable. Current hop count. Table 7 - Detailed payload for Get ER status - reply packet. Example 1: Configuration packet which requests the radio EUID (MAC address) (See Tables Sensinode Proprietary and Confidential 2011 Sensinode Ltd. 7/12

8 8 and 9) Byte number Description Length N A CT CS Byte 0x04 0x4e 0x41 0x86 0x8D Table 8 - Configuration packet for requesting the EUID. Byte number Description Length N A CT Parameters CS Byte 0x0C 0x4E 0x41 0xA6 0x12 0x23 0x34 0x45 0x56 0x67 0x78 0x89 0x25 Table 9 - Configuration packet that would be the reply to the previous request assuming the EUID to be [12:23:34:45:56:67:78:89]. Byte number Description Length N A CT Parameter CS Byte 0x05 0x4e 0x41 0xC9 0x00 0xC3 Table 10 - Set shutdown mode. Example 3: How to set Active operation mode: Byte number Description Length N A CT Parameter CS Byte 0x05 0x4e 0x41 0xC9 0x08 0xCB Table 11 - Set operation mode to Infra Router. Example 4: How to set active mode with AES enabled: Byte number Description Length N A CT Payload CS 0x09 0x00 0x01 0x02 0x03 0x04 0x05 0x06 0x07 0x08 0x09 0x0A Byte 0x0A 0x4e 0x41 0xC9 0xc5 0x0B 0x0C 0x0D 0x0E 0x0F Table 12 - Set operation mode to Infra Router with AES enabled. (key: 0x00 0x01 0x02 0x03 0x04 0x05 Sensinode Proprietary and Confidential 2011 Sensinode Ltd. 8/12

9 0x06 0x07 0x08 0x09 0x0A 0x0B 0x0C 0x0D 0x0E 0x0F). Example 5: How to Poll Network processor network status at active mode: After a mode is set the host MCU should wait until the network processor has acquired an IPv6 address before trying to send data. Easiest way to check is to send a GET ER STATUS to the Network Processor. Message response examples are described in table 13. Byte number Description Length N A CT Parameter CS Byte 0x05 0x4e 0x41 0xAB 0x00 0xA1 Table 13 - ER status reply: Not connected and not ready. Sensinode Proprietary and Confidential 2011 Sensinode Ltd. 9/12

10 3 Data packet The data packet has somewhat simpler structure when compared to configuration packet. The high-level format of Data packet is described in Table 14. The length byte is obviously interpreted the same way as with configuration packet. The CT byte structure is explained in Table 15. The CT byte is used to encode the address types (i.e. length of the addresses), the source layer of the NanoStack 2.0 that sent the data 2 and the protocol info fields that are included in the packet. The CT byte is followed immediately by the Source address of length 2, 8 or 16 bytes. The actual length can be determined by the Source type bits in the CT byte. The source address is followed by the Destination address of length 2, 8 or 16 bytes. The exact length can be determined from the Destination type bits of the CT byte. The address fields are always followed by two signal info bytes. The first byte is a signed 8 bit value representing the RSSI measured from the received packet. The second is the LQI (Link Quality Indicator) as an unsigned 8 bit value. The possible following Protocol info field length is determined by the Protocol bits in the CT byte according to Table 18. Bytes 1 2/8/16 2/8/16 2 0/2/4 x Src addr Dst addr Protocol info Description CT Signal info Data [variable length] [variable length] [variable length] Table 14 - General header format for Data packet (omitting the Length, N, A and the Checksum bytes). Bit Description D/C (0) Protocol Source type Destination type Table 15 - CT byte bits for Data packet. Field name Value Type Description Protocol See Table 17 Bit field Defines which protocol header is first in the packet payload 3 Source type See Table 18 Bit field Defines the type of the source address (c.f. Table 23) Destination type See Table 18 Bit field Defines the type of the destination address (c.f. Table 23) Table 16 - Detailed CT byte bit description for Data packet. 2 MAC (L2), Network (L3) or Transport (L4) 3 See Table 19 for details Sensinode Proprietary and Confidential 2011 Sensinode Ltd. 10/12

11 Field value Data packet (first header) Notes 011 Compressed UDP (layer 4) packet Protocol info: 4 bytes Other values Reserved for future use Table 17 - Data packet protocol field code explanation table. Field value Address type Notes 00 None - 01 IEEE Short 2 bytes 10 IEEE Long 8 bytes 11 IPv6 16 bytes Table 18 - Data packet source and destination type field code explanation table. When the data packet protocol field is UDP the Signal Info byte is immediately followed by an extra protocol info byte array. The protocol info array is four bytes for UDP packets. The exact meaning of the type of protocol info array is explained in Table 19. Byte number Source port number, low Destination port Destination port Description Source port number, high bytes byte number, high byte number, low byte Table 19 - Protocol info bytes for UDP packet. The actual data follows the protocol info bytes in UDP packets. 4 References [1] NanoStack2.0lite.pdf 5 List of abbreviations UDP User Datagram Protocol IP Internet Protocol CT Control byte CS Checksum RSSI Received Signal Strength Indicator Sensinode Proprietary and Confidential 2011 Sensinode Ltd. 11/12

12 LQI Link Quality Indicator NAP Network processor Access Protocol MAC Medium Access Control EUID Unique ID MCU Micro-controller Unit TX Transmit RX Receive IID Interface Identifier Sensinode Proprietary and Confidential 2011 Sensinode Ltd. 12/12

Embit Binary Interface - IEEE Specific Documentation. embit s.r.l.

Embit Binary Interface - IEEE 802.15.4-Specific Documentation embit s.r.l. Document information Versions & Revisions Revision Date Author Comments 1.0 A. Sala First release 1.1 14/12/2012 C. Biagi Minor