Timed Actions

CANopen Timer

The CANopen stack provides service functions for performing timed actions on the application or the profile-specific events. For timed actions the service function group COTmr…() is provided.

Event Time Base

To establishing a constant time base, the CANopen stack provides a service function. For generating a time base, the following line should be placed in a hardware timer interrupt service function, which is called periodically:

COTmrService(&demo);    /* trigger time event     */

The following diagram shows the internal behavior of this service:

sequenceDiagram
  participant H as Hardware Timer
  participant T as demo.Tmr
  H->>+T: COTmrService()
  alt elapsed timer
  note over T: store elapsed timer
  end
  T-->>-H: ok

Action Processing

The CANopen stack handles the storage and order of timed actions internally. For the execution of the timed functions a service function is provided. For processing the elapsed timer actions, the following line should be placed in a loop within the background function:

COTmrProcess(&demo);    /* process timed action(s)  */

The following diagram shows the internal behavior of this service:

sequenceDiagram
  participant A as Application
  participant T as demo.Tmr
  A->>+T: COTmrProcess()
  loop all elapsed timer
  T->>+A: call action callback
  A-->>-T: ok
  end
  T-->>-A: ok

Note: The CANopen stack uses the timed actions for standardized timed actions. In this case the shown ActionCallback function is an internal CANopen stack function.