博客

本文为在用龙芯1c做3D打印机过程中的笔记。龙芯1c做的3d打印机简称“龙印”

参考了以下两篇博文，再其基础上增加了对marlin源码的注解和我的一些理解。

http://blog.sina.com.cn/s/blog_6ad165790102vo09.html

http://blog.sina.com.cn/s/blog_679933490102vv8z.html

先来看一下

marlin中bresenham算法的相关代码。源码位于源文件“Marlin\stepper.cpp”中的函数ISR(TIMER1_COMPA_vect)内。如下

  // If there is no current block, attempt to pop one from the buffer
  if (!current_block) {
    // Anything in the buffer?
    current_block = plan_get_current_block();
    if (current_block) {
      current_block->busy = true;
      trapezoid_generator_reset();
      counter_x = -(current_block->step_event_count >> 1);
      counter_y = counter_z = counter_e = counter_x;
      step_events_completed = 0;

      #if ENABLED(Z_LATE_ENABLE)
        if (current_block->steps[Z_AXIS] > 0) {
          enable_z();
          OCR1A = 2000; //1ms wait
          return;
        }
      #endif

      // #if ENABLED(ADVANCE)
      //   e_steps[current_block->active_extruder] = 0;
      // #endif
    }
    else {
      OCR1A = 2000; // 1kHz.
    }
  }

  if (current_block != NULL) {

    // Update endstops state, if enabled
    #if ENABLED(HAS_Z_MIN_PROBE)
      if (check_endstops || z_probe_is_active) update_endstops();
    #else
      if (check_endstops) update_endstops();
    #endif

    // Take multiple steps per interrupt (For