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Customer Documentation: Neonode® Touch Sensor Module User's Guide : .ASN.1 PDU Description v1.0

Customer Documentation

Messages are transferred between communication layers as Protocol Data Units (PDUs). The zForce AIR® sensor uses ASN.1 objects to represent the information in the presentation layer.

Download the zForce® PDU definition file:  https://support.neonode.com/docs/display/downloads.

PDU definition file

How to express sensor messages in the ASN.1-format is defined in the PDU definition file. The definition file contains one or more PDUs that are defined on top level. Any data unit that is defined on top level and not referenced by any other data unit is considered to be a top level unit.

The ASN.1 standard defines a number of universal types. All other types inherit traits from these universal types. The result is that the encoding rules will be able to encode any PDU as long as the rules cover the universal types and the identifier numbers and the definition categories are available. The identifier numbers and definition categories are included in the PDU definition file. 

zForce message specification

The sensor uses three types of messages to communicate:

  • Requests
  • Responses
  • Notifications

The host sends a request to the sensor, and the device responds with a response. The device may send notifications to the host at any time.

All messages contain a virtual device address. Virtual devices are functionally isolated from each other, and communicate separately with the host. There are two types of virtual devices:

  • Platform – represents the system.
  • Air – represents one zForce touch sensor.

A sensor will always contain one platform virtual device and can contain any number of instances of other virtual device types.

The zForce PDU

All sensor messages are instances of a PDU that is defined in the zForce PDU definition file. The top level PDU ProtocolMessage contains a choice where one of the three types of children is selected:

  • Request, of PDU Message
  • Repsonse, of PDU Message
  • Notification, of PDU Notification 

The different PDUs for the zForce sensor:

 
PDU Content Explanation
Message deviceAddress Specifies the virtual device within the sensor that receives the request or sends the repsonds, respectively.
command

In a request, the command specifies what is being requested.

In a response, the command contains the result or requested information of the request.
Notification deviceAddress Specifies the virtual device within the sensor that sends the notification.
notificationMessage The message from the sensor to the host.
notificationTimestamp (optional) Timestamp.

Refer to ASN.1 PDU Examples in GSER Notation for examples.

Document generated by Confluence on Sep 11, 2025 11:01