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Standard SWAP registers

Daniel Berenguer edited this page Jun 1, 2015 · 9 revisions

Introduction

We commented in the [SWAP description page](Simple Wireless Abstract Protocol) the importance of registers. Every wireless parameter, endpoint value or user configuration setting can have a register representation. Doing this, SWAP can address very different actions using a basic packet exchange schema. In other words, using abstract data registers is the main reason of SWAP for being so simple and flexible.

Developers may create their own registers for their own purposes. However, all SWAP devices have to include a number of standard registers that provide a basic functionality, common to any SWAP mote, as a way of guaranteeing a basic interoperability between devices.

Standard registers

The following registers must be included by any device implementing the SWAP protocol:

Product code

  • Register ID = 0
  • Length = 8 bytes
  • Access: read only
  • Description: code is formed by Manufacturer ID (4 bytes) and Product ID (4 bytes)

SWAP Product Code

Manufacturer ID

Each developer or manufacturer of SWAP devices owns a unique Manufacturer ID. This ID is part of the product code of any device made by this developer.

Product Id

Each type of wireless device is identified by a unique Product ID, common to all devices of the same type belonging to the a given manufacturer.

Hardware Version

  • Register ID = 1
  • Length = 4 bytes
  • Access: read only
  • Description: 4-byte code identifying the hardware version of the wireless device

Firmware Version

  • Register ID = 2
  • Length = 4 bytes
  • Access: read only
  • Description: 4-byte code identifying the firmware version of the wireless device

System state

  • Register ID = 3

  • Length = 1 byte

  • Access: read and write

  • Description: 1-byte register used to query and control the state of the wireless device. Developers are free to define their own states but, at least, the following should be used:

  • State = 0 (RESTART) -> Restart wireless device

  • State = 1 (RXON) -> Wireless reception enabled

  • State = 2 (RXOFF) -> Wireless reception disabled

  • State = 3 (SYNC) -> Synchronization mode, wireless reception enabled

  • State = 4 (LOWBAT) -> Low battery state

  • State = 5 (UPGRADE) -> Firmware upgrade mode

Frequency channel

  • Register ID = 4
  • Length = 1 byte
  • Access: read and write
  • Description: RF frequency channel used by the wireless device

Security option

  • Register ID = 5
  • Length = 1 byte
  • Access: read and write
  • Description: type of security protection used against different wireless attacks.
  • Security option = 0 -> No security
  • Security option = 1 -> Data encryption disabled, security nonce enabled
  • Security option = 2 -> Basic data encryption enabled, security nonce enabled
  • Developers are free to define new security options, using custom encryption algorithms.

Security password

(Not supported yet)

  • Register ID = 6
  • Length = n bytes
  • Access: read and write
  • Description: Encryption password, to be used according to Security option.

Security nonce

  • Register ID = 7
  • Length = 1 byte
  • Access: read only
  • Description: when enabled, security nonces add protection against play-back attacks. As explained in the protocol definition page, security nonces can be queried before sending commands to a given device.

Network ID

  • Register ID = 8
  • Length = 2 bytes
  • Access: read and write
  • Description: each SWAP network is identified by a 2-byte code. This ID is appended by the CC11XX IC at the beginning of every wireless packet, just after the preamble.

Device address

  • Register ID = 9
  • Length = 1 byte
  • Access: read and write
  • Description: 1-byte SWAP address

Periodic Tx interval

  • Register ID = 10
  • Length = 2 bytes
  • Access: read and write
  • Description: Interval (in seconds) between periodic transmissions. panstamp.goToSleep() uses this interval to put the panStamp in power-down mode.

Custom registers

Custom registers may be of any type and any length. They must have unique register ID's and process commands and queries in the same way standard registers do, as explained in this section of the SWAP description page. However, a question arises: how can other wireless devices know about the nature of these custom registers? What if a visual application wants to display information about a given register or value? Abstract protocols like SWAP rarely solve this kind of limitation. Instead, we suggest the use of static resources, accessible from local or on-line repositories, that identify and describe wireless devices from a basic starting point: the product code.

The first custom register always takes ID = 11. The second one takes ID = 12 and so on...

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