RL-ARM User's Guide

Event Driven Operation

The event-driven operation of RL-TCPnet allows you to run TCPnet application in event-driven mode in a multitasking environment. Instead of calling the polling loop constantly, the system processess TCPnet events only when needed. The rest of time, TCPnet system remains idle.

The main_TcpNet() function is modified to return a busy status indication. If TCPnet system is busy, this function has to be called again, to complete the TCP/IP processing. If TCPnet is not busy, TCP/IP processing might be stalled, until a TCPnet event occurs.

The TCPnet events, which require TCP/IP processing, are:

• ethernet packet received,
• tick timer interval expired,
• serial character received or transmitted.

Event-driven operation optimizes the cpu usage a lot. The following table lists the cpu time required for TCP/IP processing and cpu idle time for HTTP_Demo example:

In order to modify the TCPnet application for event-driven operation, you must make the following changes to your project:

• ethernet driver
  Add the code to send a signal event to tcp_main task in the ethernet receive interrupt function.

  static void interrupt_ethernet (void) __irq {
     ...
    fetch_packet ();
    isr_evt_set(0x0001, tcp_task);
     ...
  }
  

• tcp_tick task
  Add the code to send a signal event to tcp_main task. The priority of the tcp_tick task should be higher than the priority of tcp_main task.

  __task void tcp_tick (void) {
    os_itv_set (10);
    while (1) {
      os_itv_wait ();
      timer_tick ();
      os_evt_set(0x0001, tcp_task);
    }
  }
  

• tcp_main task
  Add the code to wait for an event in TCPnet tcp_main task. The priority of tcp_main task should be higher than the application layer / service layer tasks.

  __task void tcp_main (void) {
    init_TcpNet ();
    while (1) {
      os_evt_wait_and(0x0001, 0xFFFF);
      while (main_TcpNet() == __TRUE);
    }
  }