IDT Europe ZWIR4512AC1 User Manual

User Manual

Rev. 1.20 / August 2012

ZWIR451x

Serial Command Interface

ZWIR451x

Serial Command Interface – User Manual

User Manual

August 31, 2012

All rights reserved. The material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. The information furnished in this publication is subject to changes without notice.

2 of 52

Contents

1 Introduction .......................................................................................................................................................... 6

1.1. Organization of this Document ..................................................................................................................... 6

2 Functional Description ......................................................................................................................................... 7

2.1. Interfaces ...................................................................................................................................................... 7

2.1.1. UART Interfaces ..................................................................................................................................... 7

2.1.2. SPI Interface .......................................................................................................................................... 8

2.1.3. Network Interface ................................................................................................................................... 8

2.2. Frame Format ............................................................................................................................................... 8

2.2.1. Commands and Responses ................................................................................................................... 9

2.2.2. Checksum Computation ......................................................................................................................... 9

2.2.3. Escaping................................................................................................................................................. 9

2.3. Frame Buffering .......................................................................................................................................... 10

2.4. Resets ......................................................................................................................................................... 10

2.5. Addressing .................................................................................................................................................. 10

2.5.1. PAN Identifier ....................................................................................................................................... 11

2.5.2. PAN Address ........................................................................................................................................ 11

2.5.3. IPv6 Addresses .................................................................................................................................... 11

2.6. The UDP Protocol ....................................................................................................................................... 14

2.7. Data Transmission and Reception ............................................................................................................. 14

2.8. Network Configuration ................................................................................................................................ 15

2.8.1. Physical Parameters ............................................................................................................................ 15

2.8.2. Software Parameters ........................................................................................................................... 15

2.9. Network Discovery ...................................................................................................................................... 18

2.10. Security ....................................................................................................................................................... 19

2.10.1. Internet Protocol Security (IPSec) ........................................................................................................ 19

2.10.2. Internet Key Exchange (IKEv2) ............................................................................................................ 21

2.10.3. Important Security Considerations and Recommendations ................................................................. 21

2.11. Firmware Over-the-Air Update (OTAU) ...................................................................................................... 21

2.12. General Purpose I/Os ................................................................................................................................. 22

2.13. Watchdog Timer ......................................................................................................................................... 23

2.14. Persistent Parameter Storage .................................................................................................................... 24

3 Command Reference ........................................................................................................................................ 25

3.1. Transmit Frame Command ......................................................................................................................... 26

3.2. Configure Receiver Command ................................................................................................................... 27

3.3. Get TRX Statistics ...................................................................................................................................... 28

3.4. Reset TRX Statistics ................................................................................................................................... 28

3.5. Configure Wake-up Command ................................................................................................................... 28

3.6. Power-Down Command.............................................................................................................................. 31

3.7. Get Address Configuration Command ........................................................................................................ 31

3.8. Set PAN Address ........................................................................................................................................ 32

3.9. Set PAN ID ................................................................................................................................................. 32

3.10. Configure PHY ............................................................................................................................................ 33

3.11. Configure Network ...................................................................................................................................... 34

3.12. Discover Network ........................................................................................................................................ 35

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Serial Command Interface – User Manual

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3.13. Remote Execute ......................................................................................................................................... 35

3.14. Get Firmware Version ................................................................................................................................. 35

3.15. Reset........................................................................................................................................................... 36

3.16. Network Reset ............................................................................................................................................ 36

3.17. Store Configuration ..................................................................................................................................... 36

3.18. Test ............................................................................................................................................................. 37

3.19. Configure LEDs Command ......................................................................................................................... 37

3.20. Configure GPIO .......................................................................................................................................... 38

3.21. Write GPIO ................................................................................................................................................. 38

3.22. Read GPIO ................................................................................................................................................. 39

3.23. Toggle GPIO ............................................................................................................................................... 39

3.24. Configure UART1 ....................................................................................................................................... 40

3.25. Configure UART2 ....................................................................................................................................... 40

3.26. Configure SPI ............................................................................................................................................. 41

3.27. Restore Fabric Settings .............................................................................................................................. 42

3.28. Configure Multicast ..................................................................................................................................... 42

3.29. Join Multicast Group ................................................................................................................................... 43

3.30. Leave Multicast Group ................................................................................................................................ 43

3.31. Add Security Policy ..................................................................................................................................... 43

3.32. Add Security Association ............................................................................................................................ 44

3.33. Add IKEv2 Authentication Entry ................................................................................................................. 45

3.34. Enable Watchdog Timer ............................................................................................................................. 46

3.35. Get Current Interface .................................................................................................................................. 46

3.36. Get PHY Configuration ............................................................................................................................... 46

3.37. Get NET Configuration ............................................................................................................................... 47

3.38. Get FCC ID ................................................................................................................................................. 47

3.39. Receive Packet Command ......................................................................................................................... 47

3.40. Remote Response Command .................................................................................................................... 47

4 Certification ........................................................................................................................................................ 48

4.1. European R&TTE Directive Statements ..................................................................................................... 48

4.2. Federal Communication Commission Certification Statements ................................................................. 48

4.2.1. Statements ........................................................................................................................................... 48

4.2.2. Requirements ....................................................................................................................................... 48

4.3. Supported Antennas ................................................................................................................................... 49

5 Abbreviations ..................................................................................................................................................... 50

6 Related Documents ........................................................................................................................................... 51

7 Document Revision History ............................................................................................................................... 52

ZWIR451x

Serial Command Interface – User Manual

User Manual

August 31, 2012

All rights reserved. The material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. The information furnished in this publication is subject to changes without notice.

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List of Figures

Figure 2.1 Frame Format ........................................................................................................................................ 9

Figure 2.2 General IPv6 Address Layout .............................................................................................................. 12

Figure 2.3 IPv6 Multicast Address Layout ............................................................................................................ 12

Figure 2.4 Multicast Addressing: Group ID Configuration..................................................................................... 14

Figure 2.5 Example of Network Topology 1 .......................................................................................................... 16

Figure 2.6 Example of Network Topology 2 .......................................................................................................... 17

Figure 2.7 IPSec Working Principle ...................................................................................................................... 20

Figure 2.8 Layout of the Pin Configuration Bit-Field ............................................................................................. 23

Figure 3.1 Configure Wakeup - Peripheral Field Format ...................................................................................... 30

Figure 3.2 Remote Execute Command Frame Layout ......................................................................................... 35

Figure 3.3 UART Configuration Bit-Field Layout ................................................................................................... 40

Figure 3.4 SPI Configuration Bit-Field Layout ....................................................................................................... 41

Figure 8.1 FCC Compliance Statement to be printed on Equipment Incorporating ZWIR4512 Devices ............. 49

List of Tables

Table 2.1 Interface Dispatch Numbers .................................................................................................................. 7

Table 2.2 UART Configuration and Pin Description .............................................................................................. 7

Table 2.3 UART Configuration Options ................................................................................................................. 7

Table 2.4 SPI Pin Description ................................................................................................................................ 8

Table 2.5 SPI Configuration Options ..................................................................................................................... 8

Table 2.6 General Error Responses ...................................................................................................................... 9

Table 2.7 GPIO Operating Modes ....................................................................................................................... 22

Table 2.8 Default I/O Configuration of Preconfigured Pins .................................................................................. 22

Table 3.1 Command Overview ............................................................................................................................ 25

Table 3.2 Transmit Frame Command Fields ....................................................................................................... 26

Table 3.3 Transmit Frame Command Responses ............................................................................................... 27

Table 3.4 RXSetup Command Fields .................................................................................................................. 27

Table 3.5 RXSetup Command Responses .......................................................................................................... 27

Table 3.6 Get TRX Statistics Response Format .................................................................................................. 28

Table 3.7 Transmission Duty-Cycle Requirements of Sub-GHz Devices in the European Union ...................... 28

Table 3.8 Wakeup Sources .................................................................................................................................. 29

Table 3.9 Configure Wakeup Command Fields ................................................................................................... 30

Table 3.10 Configure Wakeup Command Responses .......................................................................................... 30

Table 3.11 Power Down Command Fields ............................................................................................................ 31

Table 3.12 Power Down Command Responses .................................................................................................... 31

Table 3.13 Get Address Configuration Response Fields....................................................................................... 32

Table 3.14 Set PAN Address Command Fields ..................................................................................................... 32

Table 3.15 Set PAN Address Command Responses ............................................................................................ 32

Table 3.16 Set PAN ID Command Fields .............................................................................................................. 33

Table 3.17 Set PAN ID Command Responses ...................................................................................................... 33

Table 3.18 Configure PHY Command Fields ......................................................................................................... 33

Table 3.19 Configure PHY Command Responses ................................................................................................ 33

Table 3.20 Configure Network Command Fields ................................................................................................... 34

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August 31, 2012

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Table 3.21 Response Codes of the Configure Network Command ....................................................................... 35

Table 3.22 Remote Execute Response Codes ...................................................................................................... 35

Table 3.23 Get Firmware Version Command Responses ..................................................................................... 36

Table 3.24 Store Configuration Command Fields .................................................................................................. 36

Table 3.25 Store Configuration Command Responses ......................................................................................... 37

Table 3.26 Test Command Fields .......................................................................................................................... 37

Table 3.27 Test Command Responses ................................................................................................................. 37

Table 3.28 Configure LEDs Command Fields ....................................................................................................... 37

Table 3.29 Configure LEDs Command Responses ............................................................................................... 38

Table 3.30 Configure GPIO Command Fields ....................................................................................................... 38

Table 3.31 Configure GPIO Responses ................................................................................................................ 38

Table 3.32 Write GPIO Command Fields .............................................................................................................. 38

Table 3.33 Write GPIO Responses ........................................................................................................................ 39

Table 3.34 Read GPIO Command Fields .............................................................................................................. 39

Table 3.35 Read GPIO Command Responses ...................................................................................................... 39

Table 3.36 Toggle GPIO Command Fields ............................................................................................................ 39

Table 3.37 Toggle GPIO Command Responses ................................................................................................... 39

Table 3.38 Configure UART Command Fields ...................................................................................................... 40

Table 3.39 Configure UART Command Responses .............................................................................................. 40

Table 3.40 Configure SPI Command Fields .......................................................................................................... 41

Table 3.41 Configure SPI Command Responses .................................................................................................. 41

Table 3.42 Restore Fabric Settings Command Fields ........................................................................................... 42

Table 3.43 Restore Fabric Settings Command Responses................................................................................... 42

Table 3.44 Configure Multicast Command Fields .................................................................................................. 42

Table 3.45 Configure Multicast Command Fields .................................................................................................. 42

Table 3.46 Join Multicast Group Command Fields ................................................................................................ 43

Table 3.47 Join Multicast Field Command Responses .......................................................................................... 43

Table 3.48 Leave Multicast Group Command Fields ............................................................................................. 43

Table 3.49 Leave Multicast Group Command Responses .................................................................................... 43

Table 3.50 Add Security Policy Command Fields .................................................................................................. 44

Table 3.51 Add Security Policy Command Responses ......................................................................................... 44

Table 3.52 Add Security Association Command Fields ......................................................................................... 45

Table 3.53 Add Security Association Command Responses ................................................................................ 45

Table 3.54 Add IKEv2 Authentication Entry Command Fields .............................................................................. 45

Table 3.55 Add IKEv2 Authentication Entry Command Responses ...................................................................... 46

Table 3.56 Enable Watchdog Timer Command Fields .......................................................................................... 46

Table 3.57 Get PHY Command Response ............................................................................................................ 46

Table 3.58 Get NET Command Response ............................................................................................................ 47

Table 3.59 Receive Packet Command Fields ........................................................................................................ 47

Table 3.60 Remote Response Command Fields ................................................................................................... 47

ZWIR451x

Serial Command Interface – User Manual

User Manual

August 31, 2012

All rights reserved. The material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. The information furnished in this publication is subject to changes without notice.

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1 Introduction

This document describes the features and the usage of the ZWIR451x module with the Serial Command Interface (SCI) firmware. The SCI allows using ZWIR451x modules without programming the module. The ZWIR451x modules are delivered preprogrammed and tested and can be integrated into the application without programming. The module provides several serial interfaces that can be used independently to control the module.

The SCI module provides firmware over-the-air update (OTAU) capability, data encryption, and data authentication in addition to the normal User Datagram Protocol (UDP) communication. Integration into normal computer networks is possible without restrictions.

1.1. Organization of this Document

The following section gives a functional overview of the serial command interface firmware. The different interfaces, mechanisms, and functionalities are explained in this section. Section 3 documents all available commands.

In order to differentiate between decimal, hexadecimal, and binary number representations, this document uses the convention to subscript binary and hexadecimal numbers with a capital B or H, respectively.

In section 3, command argument fields and responses are explained in a table format. Interpret tables for command argument fields as a list: the first table row is the first command argument; the second row represents the second argument, and so on. For responses, the same rule applies if there is no code field in the table. Otherwise, the table is interpreted in the following way: The code is the first field contained in the response. All fields (second column of the table) in the same row as the code field follow the code in the response.

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Interface

Dispatch Value

UART1

0

UART2

1

SPI

2

Network

3

UART-Pin Name

Usage

Direction

Module Pin

UART1

UART2

Transmit (TX)

Mandatory

Output

13 6 Receive (RX)

Mandatory

Input

12

5

Request to send (RTS)

Optional

Output

17

7

Clear to send (CTS)

Optional

Input

16

8

Option

Default Configuration

Configuration Options

Data Transfer Rate

115200 Baud

61

(1)

baud – 256000

(2)

baud

Parity

Not enabled

Odd, Even

Number of Stop Bits

1 2 Flow-Control

Not enabled

Hardware Flow Control

(1) 61 baud can only be achieved on UART2. The minimum baud rate of UART1 is 122. (2) The maximum rate of 256000 baud can only be achieved on UART1. The maximum rate of UART2 is 115200 baud.

2 Functional Description

2.1. Interfaces

The module provides two UART and one SPI interface for communication with external hosts. The host can also execute commands over the network interface. Hosts can be computers, microcontrollers, or even single sensors that have an appropriate interface. It is possible to connect different devices to different interfaces. All communication interfaces are enabled in the SCI default configuration.

The SCI firmware allows sending incoming network data to any of the available interfaces. For this purpose, the Configure Receiver command expects a dispatch value that specifies to which of the serial interfaces incoming data is sent. Table 2.1 shows the dispatch numbers for the different interfaces.

Table 2.1 Interface Dispatch Numbers

2.1.1. UART Interfaces

The module provides two UART interfaces. By default, both interfaces operate at a data rate of 115200 kBaud, have 8 data bits, one stop bit, no parity bit, and no flow control. The UART configuration can be changed at any time using one of the commands Configure UART1 or Configure UART2. Any interface can be used to change the UART configuration.

Table 2.2 UART Configuration and Pin Description

Table 2.3 UART Configuration Options

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SPI Pin Name

Direction

Usage

Module Pin

Master Out Slave In (MOSI)

Input

Mandatory

1

Master In Slave Out (MISO)

Output

Mandatory

2

Clock

Input

Mandatory

3

Slave Select

Input

Optional

4

Data Pending

Output

Optional

7

Value

Default

Configuration Option

Clock Polarity

Low ( clock is low when idle )

High

Clock Phase

First edge captures data

Second edge captures data

Pending Pin Mapping

Module pin 7

2.1.2. SPI Interface

The module provides an SPI interface that is operating in slave mode. To control the SCI module via the SPI, the host computer must provide an SPI clock whenever data is to be sent or received. Availability of data from the SCI module is signaled by a dedicated line that is pulled low when data is available for read-out. If the host needs to receive data and no data is to be transmitted, sending zeros is recommended. The ZWIR451x will send zeros over its MISO line if the master is transmitting a frame and no data has to be transmitted to the host.

The default configuration uses the SSN pin to activate the SCI node. Data is only received and transmitted if the SSN pin is pulled to low. The SPI is configured for MSB first transmission and reception; the clock is low when idle; and the first clock transition is used as data capture edge.

Table 2.4 SPI Pin Description

Table 2.5 SPI Configuration Options

2.1.3. Network Interface

The network interface allows executing commands remotely. Basically this works like the serial interfaces with the difference that command frames sent over the network interface do not have to carry the START byte and data escaping is not required. All available commands can be executed remotely. For some commands restrictions apply.

Each SCI node listens to UDP port 4 for incoming command frames. If a command is received, it is executed and if there is any response from the command, the response is sent back to the device that requested execution of the command.

The SCI also implements the Remote Execute command, which allows initiation of a remote execution over one of the serial interfaces.

2.2. Frame Format

Command and responses are sent over the different physical communication interfaces in data frames that have a special format that allows detecting communication errors and introduces low overhead. All frames have a common format.

The frame format is illustrated in Figure 2.1. Each frame starts with the START delimiter 7EH. The following two bytes determine the length of the frame payload. Length information is stored in Little Endian format; hence, the least significant byte is stored first. The third byte determines the command to be executed. The following N bytes

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Code

Field

Length

Description

1

Invalid Header

3

Message larger than the maximum allowed size or unknown command.

2 - Invalid checksum.

3

Interface

1

A framing, parity, overflow, or noise error at the UART or SPI interface occurred.

Command

1

Pos. of Last Valid Byte

2 4 Internal Error Code

4

An internal error occurred.

5 - Duplicate address detection failed.

30

Failing IPv6 Address

16

The address resolution for the address returned in the response failed. This error occurs sometime after attempting to send an unicast frame to a destination.

START

1 byte

LENGTH

2 bytes

CMD

1 byte

CHKS

1 byte

PAYLOAD

LENGTH bytes

are the frame payload. At the end of the frame, a checksum byte is attached, which helps to detect communication errors.

Figure 2.1 Frame Format

2.2.1. Commands and Responses

The Serial Command Interface firmware distinguishes Command and Response Frames. Command Frames are sent in order to trigger a specific action at the receiver of the Command Frame. Response Frames contain status information sent in response to Command Frames. Typically Response Frames are only sent if an error was encountered in the last Command Frame.

A Command Frame has a Command Code in the range of 01H to 7FH. The values 00H, 1BH and 7EH are not allowed. An overview of all available commands and their command codes can be found in Table 3.1.

The Command Code of a Response Frame is the Command Code of the Command Frame that triggered the Response OR’ed with 80H. The Response Frame with the Command Code 80H is a special response frame that is sent when an invalid frame was received or another non-command-related error occurred.

Table 2.6 General Error Responses

2.2.2. Checksum Computation

At the end of each packet a checksum is appended that helps to detect transmission errors on the physical transmission medium. The checksum is formed in such way that the sum of all transmitted bytes, excluding the Start character 7EH is zero. If the sum of all received bytes of a packet does not result in zero, a Frame Error packet with its error code set to CHECKSUM_ERROR is sent over the same interface the erroneous packet was received on.

2.2.3. Escaping

If one of the characters 1BH or 7EH is contained in the data stream or one of the frame control fields, this character must be escaped by XOR’ing it with 80H and prepending it with 1BH. This modification has no effect on the length field of the frame, even if it is done in the payload section of the frame. However, escaping must be considered for checksum calculation.

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If the checksum of the device is one of ZMDI’s two control characters, the checksum must be escaped as well. Escaping the checksum is done by sending the escape character 1BH followed by the computed checksum value minus 1BH

The following examples illustrate how escaping must be performed:

7e 04 00 12 1a 1b 1c 1d 7c

7e 04 00 12 1a 1b 9b 1c 1d e1

7e 1b 00 01 ff 02 00 00 00 00 00 00 00 00 00 00 00 00 00 01 7e 03 01 02 03 04 05 06 07 08 09 34

7e 1b 9b 00 01 ff 02 00 00 00 00 00 00 00 00 00 00 00 00 00 01 1b fe 03 01 02 03 04 05 06 07 08 09 fe

7e 04 00 10 24 9f 32 79 7e

7e 04 00 10 24 9f 32 79 1b 63

2.3. Frame Buffering

Each communication interface maintains its own message queue. In situations of high load, messages are queued temporarily in the message queue. Each interface has its own message queue. The message queue distinguishes between command frames and response frames. Response frames are queued at the beginning of the queue, while command frames are queued at the end of the queue. This ensures that response frames are sent immediately after the triggering command frame. However, if a command frame is being sent when a response frame is queued, the transmission of the command frame is completed before the response frame is sent.

2.4. Resets

The SCI module provides two types of reset. One is System Reset; the other one is Network Reset. System Reset puts the device into the state that it has after a power-on. It executes the complete startup procedure of the microcontroller and the transceiver in order to put them into a defined state. All settings are restored to the fabric default values or to the configuration that was saved to the flash memory the last time. System Reset is also performed automatically in the event of an unrecoverable error. If System Reset is performed because of an error, an error message is sent over the interface the last instruction was received from. This message usually contains an error description. The most common error for System Reset is a memory allocation failure, which can appear after changing the network configuration or after configuring multicast. Refer to the documentation of the Configure Network and Configure Multicast commands.

Network Reset is used after changing the network configuration. It does not perform a System Reset. A Network Reset disconnects all open connections and applies changes in network parameters that have been applied before. The command Configure Network performs a reset automatically to apply the settings that have been made. Network Reset does not affect the physical parameter set with Configure PHY.

2.5. Addressing

Each SCI module has three types of addresses. The PAN Identifier, the PAN Address and the IPv6 Address(es) are described in the following sections.

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2.5.1. PAN Identifier

This address identifies the network the device is operating in. All devices that are part of the same network must use the same PAN identifier. Devices with different PAN identifiers are not able to communicate with each other, even if they are in the physical range of each other and have the same PHY settings applied.

The PAN Identifier is a 16-bit number. Its default value is ACCAH. This value is changed using the command Set PAN ID.

2.5.2. PAN Address

The PAN address is the hardware address of the device. The PAN address is also commonly known as the MAC address. The PAN address of the SCI module is a 64-bit number that is formed according to the EUI-64 rules. Each device in the network MUST have a unique PAN address. This address is used to generate locally and globally unique IPv6 addresses (see section 2.5.3.1). Usually applications do not have to process the PAN address directly.

ZMDI’s ZWIR451x SCI Modules have a globally unique address preprogrammed. This enables generation of locally and globally unique IPv6 addresses without any need for initial configuration. ZMDI does not recommend changing the PAN address of the device. However, if the application requires this, it is supported by the command Set PAN Address.

2.5.3. IPv6 Addresses

The IPv6 addresses are the addresses the applications are dealing with. These addresses are 128-bit wide. Each device must have at least one IPv6 address in order to be able to communicate. Using IPv6 addresses, the application determines where packets are sent to and received from. How IPv6 addresses are set up and how they are presented is explained below.

IPv6 addresses are 128-bit, thus 16-byte wide. As it would be impractical to use the byte-wise notation known from the old IPv4, IPv6 introduces a new notation. IPv6 addresses are represented by eight 16-bit hexadecimal numbers that are separated by colons. An example for such address is

2001:0db8:0000:0000:1b00:0000:0ae8:52f1

Leading zeros of segments can be omitted as they do not carry information. The IPv6 notation allows omitting a sequence of zero-segments and representing it as double colon. With these rules, the above address can be written as

2001:db8::1b00:0:ae8:5211 or 2001:db8:0:0:1b00::ae8:52f1.

However, replacing multiple zero segments is not allowed. Thus the address

2001:db8::1b00::ae8:5211

is invalid. In order to explain IPv6 addresses, the term “link” must be defined. Nodes are said to be on the same link when

they are able to communicate with each other without requiring any routers. Nodes on the same link are able to communicate on the MAC level.

An IPv6 address consists of two components: a prefix and an interface identifier. The prefix specifies the network a device is part of while the interface identifier specifies the interface of a device. The size of the prefix varies for different address types. In the IPv6 address notation, the prefix length can be appended to the address with a slash followed by the number of prefix bits. Thus the notation 2001:db8::/64 represents a network containing the addresses from 2001:db8:: to 2001:db8::ffff:ffff:ffff:ffff.

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Prefix

127

0

Group Identifier (GID)

FFH

Scope

Flags

112

116

120

127

112

Prefix

127 n n-1

0

Interface Identifier (IID)

Figure 2.2 General IPv6 Address Layout

IPv6 supports three kinds of addressing methodologies: unicast addressing, multicast addressing, and anycast addressing. Unicast addressing is used to communicate to well defined remote nodes. Using multicast addressing packts may be sent to multiple addresses at the same time. Anycast addressing is used to reach any node out of a group of nodes which share the same anycast address. ZMDI’s SCI firmware doesn’t allow nodes to have anycast addresses. However, remote anycast nodes (e.g. compuers in the network) can be reached. A network node may have multiple interfaces; e.g. it may incorporate multiple radio nodes or multiple Ethernet cards. Unicast addresses are used to address a single interface in the network. The prefix of the address determines the scope of the unicast address. This may be link-local or global. All unicast addresses with a prefix starting with 0b000 (bits 125 to 127) have a 64-bit interface identifier. If the prefix equals fe80::/64, this is a link-local unicast address. Link local addresses are valid only on the link the interface is connected to. The prefix of global unicast addresses is typically received from a router via address autoconfiguration. If the router is not connected to the internet, the node will not get a global address, only a local one. Besides local and global prefixes, there are further prefix configurations with limited scope that are not covered by this documentation. Refer to RFC 4291 for more detailed information about alternative prefix configurations.

Multicast allows sending packets to multiple receivers at the same time. For this purpose, IPv6 provides multicast addresses. This class of addresses must only be used as destination address. It MUST NOT be used as a source address in IPv6 packets. Figure 2.3 shows the layout of multicast addresses. They have a 16-bit prefix with the most significant eight bits set to ffH, followed by two 4-bit fields for flags and the scope of the multicast packet. The lower 112 bits specify the multicast group id. A device checks if it is part of a multicast group depending on the multicast group ID.

Figure 2.3 IPv6 Multicast Address Layout

For the flags field, ZMDI’s IPv6 stack only supports the values 0000B and 0001B. The first version specifies that the multicast address is a well-known address (an address that has been assigned by the IANA). The second one marks the address as a temporarily assigned address that is not specified by internet standards. Custom multicast addresses MUST use the latter version of multicast addresses!

For the scope field, any allowed value is supported. However values above 0010B require appropriately configured routers.

Two addresses are of special interest, as they are used very often.

1. The unspecified address :: - All segments of this address are zero. It is used by receivers to listen to any sender. This address must never be used as destination address.

2. The link-local all nodes multicast address ff02::1 – Packets sent to this address are received by all nodes on the link. Thus this multicast address is equivalent to link-local broadcasting.

For further information about IPv6 addressing, refer to RFC 4291 – “IP Version 6 Addressing Architecture.”

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Serial Command Interface – User Manual

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August 31, 2012

All rights reserved. The material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. The information furnished in this publication is subject to changes without notice.

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2.5.3.1. IPv6 Address Autoconfiguration

In order to make node configuration and setup as easy as possible, IPv6 provides a stateless autoconfiguration mechanism for IPv6 addresses. Using this algorithm, IPv6 unicast addresses are generated automatically from information statically available on the interface and information provided by routers on the link. If no router is present, only an IPv6 address with link-local scope is generated. Global addresses are generated if the router advertises prefix information. Thus, no manual address assignment is required and no server-based address assignment technology, such as DHCP, needs to be provided.

The stateless address autoconfiguration mechanism uses the PAN address (refer to section 2.5.2) of the interface to generate the device’s IPv6 addresses. For both address scopes, link-local and global scope, this is done by putting a 64-bit prefix in front of the modified 64-bit PAN address of the interface. The modification of the PAN address refers to toggling the universal/local bit of the interface identifier. This method is described in Appendix A of RFC 4291. Assuming a PAN address of 00:11:7d:00:00:12:34:56 and a prefix 2001:db8::/64, this would result in the global IPv6 address 2001:db8::211:7d00:12:3456. Accordingly the link-local address would be generated by using the link-local prefix fe80::/64 and result in the IPv6 address fe80::211:7d00:12:3456. Note that in both cases, the modification coming from the modified PAN address is highlighted in red.

IPv6 requires that addresses that are assigned to an interface are checked for their uniqueness on the link. This is done using the Duplicate Address Detection (DAD) algorithm. DAD is not required if the universal/local bit in the interface identifier of the IPv6 address is set to 1 (like in the example above). The DAD algorithm is described in more detail in section 2.5.3.3.

2.5.3.2. Multicast

IPv6 Multicast allows sending packets to multiple receivers at the same time. Sending packet to multiple receivers is done by simply using a multicast address as the destination address. All devices that want to receive packets sent to a particular multicast address must join the appropriate multicast group before they are able to receive packets. The receiver must be configured appropriately to receive packets from the sender. Refer to section 2.7 for more detailed information on configuring devices for data reception.

The ZWIR451x SCI firmware provides a flexible multicast implementation supporting up to 16384 (214) groups. Depending on the multicast configuration of the device, 7 to 112 groups can be accessed simultaneously. When multicast is configured, a bit-field is allocated in the devices with each bit representing the status of a certain group membership status of the device. Joining a certain group will set the corresponding bit in the bit-field internally, while leaving that group will delete the bit. Each device can join as many groups as it wishes.

In order to send data to one or multiple groups, the destination address must be formed appropriately according to the selected multicast configuration. ZMDI’s multicast implementation allows flexible configuration of the way multicast groups are addressed in the network. The multicast GID basically is divided into two sections. The lower bits are interpreted as a bit mask that is logically AND’ed with the internally stored bit-field of a receiving device in order to determine if the device is part of the requested multicast group. The remaining bits that are not in the bitmask are interpreted as 16-bit group addresses. Each multicast device MUST configure multicast. During the multicast configuration, specify how many of the upper 16 fields of an IPv6 multicast address are interpreted as the group address. The remaining bits are interpreted as bit-field. The general layout of the multicast GID is shown in Figure 2.4. Parameter N is the configured number of group address fields. Note that all devices in the network must use the same multicast configuration.

ZWIR451x

Serial Command Interface – User Manual

User Manual

August 31, 2012

All rights reserved. The material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. The information furnished in this publication is subject to changes without notice.

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Prefix

127

0

Group Identifier (GID)

GADR

N-1

112 – 16

112

GADR0

Group Bit-Mask (112 – N*16 bits)

112 – N*16

0

Figure 2.4 Multicast Addressing: Group ID Configuration

2.5.3.3. Validation of IPv6 Address Uniqueness

Duplicate address detection (DAD) is performed to check if an IPv6 address is unique on the link. For this purpose, a node starts to send neighbor solicitation (NS) messages to the address to be checked. If another node replies to one of those messages or if another node also sends neighbor solicitation messages to this address, the assigned address is not unique and must not be used. In such cases, a system reset is performed, and an error message is sent to the interface that the last command was received from. Note that this error can only happen if some of the devices in the application use manually configured IPv6 addresses or PAN addresses. Therefore, it is recommended that manually configured addresses not be used!

2.6. The UDP Protocol

The User Datagram Protocol (UDP) is used for data transmission in ZWIR451x devices. UDP is a connectionless and lightweight protocol, introducing minimal communication and processing overhead. No connection has to be created, and no network traffic is required before data transmission between nodes can be started. Instead, communication is possible immediately. UDP does not guarantee that packets that have been sent are reaching the receiver. If reliable transmission is required, acknowledges must be implemented on the application level. It is also possible that the same UDP packet is received multiple times. Furthermore, it is not guaranteed that the receive order of packets at the destination is the same as the send-order at the source. This must be considered by the application programmer.

UDP uses the concept of ports to differentiate different data streams to a node. A port can be seen as the address of a service running on the receiver of a packet. Depending on the destination port of a packet, the network stack decides to which network service the packet is routed. UDP distinguishes 65636 ports. The SCI firmware on ZWIR451x simply transmits data that have been received on a certain connection to one of its interfaces. It is possible to assign different interfaces to different ports.

The SCI firmware opens three UDP connections automatically. These connections are required for the remoteexecution of commands, the Internet Key Exchange protocol, and the Over-the-Air firmware update feature. The ports allocated for these services are listed below. They must not be used by the application.

 Port 4: Remote Execution  Port 500: Internet Key Exchange version 2  Port 1357: Over-the-Air Update

2.7. Data Transmission and Reception

Data transmission is requested with the Transmit Data command. This command allows specification of the destination IPv6 address and the UDP port that the packet should be sent to. The source port of the transmission is selected randomly.

In order to receive packets from a remote device, the receiver must be configured appropriately. For that purpose, the command Configure Receiver is provided. It allows configuring the source address of the device that data should be received from and the UDP port that data should be received on. It is possible to determine to which

ZWIR451x

Serial Command Interface – User Manual

User Manual

August 31, 2012

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interface that data traffic received on the particular connection is sent to. The source address argument SHOULD be a unicast address, if data reception from a particular device is expected. Alternatively it is possible to use the unspecified address that will accept data from any sender.

For successful data transmission, the UDP port configured at the receiver must match the UDP port that data is sent to.

2.8. Network Configuration

ZWIR451x network parameters are configurable to match the needs of the application. Especially for large installations with mesh routing, adjusting settings for optimal performance is strongly recommended.

2.8.1. Physical Parameters

ZWIR451x’s SCI firmware allows configuring the radio channel, the signal modulation, and the transmission power. In order to be able to communicate, all devices must use the same channel and modulation settings. All physical parameters are changed with the command Configure PHY.

Note that the European Union restricts the output power of devices in the SRD extension band (865 MHz – 868 MHz) to 1 mW. For that reason, it is not possible to select an output power of more than 0dBm for these bands. Otherwise an error message is returned.

2.8.2. Software Parameters

The software parameters control the behavior of the network stack. All of these parameters are changed using the command Configure NET.

2.8.2.1. IPv6 Network Parameters

The Neighbor Cache Size determines how many neighbor cache entries are allocated by the network. Neighbor cache entries are required for each remote endpoint a device wishes to communicate via unicast to. Considering an example network topology as shown in Figure 2.5, the devices must have the following number of neighbor cache entries:

D1  1 entry D2  1 entry D3  2 entries D4  3 entries

Thus for each outgoing connection (arrow is pointing away from device), a neighbor cache entry is required.

ZWIR451x

Serial Command Interface – User Manual

User Manual

August 31, 2012

All rights reserved. The material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. The information furnished in this publication is subject to changes without notice.

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D1

D2

D3

D4

Figure 2.5 Example of Network Topology 1

The Maximum Socket Count parameter determines how many sockets may be open at the same time. This is important for concurrent reception of different data streams.

The Neighbor Reachable Time parameter determines the time a neighbor cache entry is considered as reachable before reachability is verified by the network stack automatically. Usually this parameter is configured by routers present in the network. Thus, if a router is present, the configured value is overwritten with the value received from router advertisements.

The Duplicate Address Detection Enable flag determines if duplicate address detection (DAD) is performed during interface initialization or when a new address is assigned to the interface. Duplicate address detection is used to verify that no other device in the network is using the same address as the address verified. DAD causes one broadcast packet to be sent during interface initialization. The interface is not available for user communication before the DAD packet is sent and some delay to receive an answer has passed. The time before availability of the interface or a newly assigned IPv6 address is between one and two seconds if DAD is enabled. If DAD is disabled, the interface or newly assigned addresses are available immediately and no packet is sent out by the device. However, leaving DAD enabled is recommended for protection from network failures caused by duplicate addresses. A device that is unable to initialize its interface correctly will report an error and go to Standby Mode until it is being reset.

The Router Solicitation Enable flag determines if the device sends router solicitations to the network. This is typically done to obtain network configuration information such as address lifetimes and reachable times as well as global network prefixes. If there will never be a router on the network, this option can be disabled. Otherwise the option should be left enabled. Usually routers send configuration information autonomously at a certain time interval. If delayed reception of router information is acceptable, the Router Solicitation Enable flag may be unset. However, care must be taken to ensure that the router information advertised on a regular basis contains the same amount of information as the solicited advertisements.

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