...

Downloading the definition file

Download the zForce® PDU zForce® PDU definition file here Downloads.

Type, Length, Value

All ASN.1 messages are structured by type, length and value:

...

The encoding for tag numbers up to and including 30 (higher code numbers are encoded differently, but those are not used in our protocol):

In short this means that the 8th and 7th bits are reserved to specify the class, and the 6th bit is reserved to show if it is a sequence. Bits 5 to 1 are used to specify the tag number.

Example: The type byte for the command deviceConfiguration

The command as seen in the protocol:

The encoding for tag numbers 31 and higher:

Example: The type byte for the command deviceConfiguration

The command as seen in the protocol:

deviceConfiguration [APPLICATION 19] 

deviceConfiguration [APPLICATION 19] Sequence 

This tells us that the deviceConfiguration is a sequence with the class tag Application and 19 as tag number. The deviceConfiguration type byte looks like this when it is represented as an octet:

...

The decimal value 50 translates to 0x32 in hexadecimal representation and 0011 0010 in binary representation

Example: The length bytes for a value that is 300 bytes long

The length bytes for a value that is 300 bytes long consists of three bytes. The first byte indicates that the following two bytes ((0x01) 0000 0001 (0x2C) 0010 1100) should be added together. The first byte is described in the following table:

The Value Byte(s)

The value byte(s) can be as few as one byte or they can be a whole sequence following the Type Length Value format: 

• Integers are represented by one or more bytes. :
  • An integer between 0 and 127 is represented by one byte (00 to 7F).
  • An integer between 128 and
  32767
  • 32 767 is represented by two bytes (00 80 to 7F FF).
  • An integer between 32 768 and 8 277 607 as three bytes (00 80 00 to 7F FF FF).
  • Etc.
• A Boolean only requires one byte, since it is either true or false. The Boolean is either 0x00 or 0xFF.
• An Octet String takes up just as many bytes as the number of octets.

• Bit string: the number of bytes needed to represent a bit string depends on the number of bits and is easily explained in code:

  Code Block
  theme Confluence
  int valueLength = 0; void CalculateValueLength() { valueLength = bitString.Length / 8; if((bitString.Length % 8) != 0) { valueLength++; } }

  Anchor
  RequestResponseNotification RequestResponseNotification

...

*Device Configuration ASN.1 Protocol* 
-- Instance specific settings for a device
   deviceConfiguration [APPLICATION 19] Sequence {
            -- Set / get the number of touches to be tracked:
            numberOfTrackedTouches    [0] INTEGER (0..255) OPTIONAL,
            -- Set / get the minimal distance for updating a tracked touch in move state
            trackingMinDistanceMove    [1] INTEGER (0..16383) OPTIONAL,
            -- Set / get the sub touch active area lowlower bound in X coordinate
            subTouchActiveArea        [2] Sequence {
                -- Write Request and Read Response only:
                -- Set / get the sub touch active area low bound in X coordinate
                lowBoundX        [0] INTEGER (0..16383) OPTIONAL,
                -- Set / get the sub touch active area low bound in Y coordinate
                lowBoundY       [1] INTEGER (0..16383) OPTIONAL,
                -- Set / get the sub touch active area high bound in X coordinate
                highBoundX    [2] INTEGER (0..16383) OPTIONAL,
                -- Set / get the sub touch active area high bound in Y coordinate
                highBoundY    [3] INTEGER (0..16383) OPTIONAL,

...

We want to set the following settings in the sensor module

SubTouchActiveArea:

• LowBoundX: 500
• LowBoundY: 500
• HighBoundX: 2000
• HighBoundY: 2000

settings in the sensor module

SubTouchActiveArea:

• LowBoundX: 500
• LowBoundY: 500
• HighBoundX: 2000
• HighBoundY: 2000

This is how to do it (the length bytes are represented by XX, and are added in the last step):