Generation of Square Wave

1. Purpose
   
   In this section, square wave which repeats 0[V] and 1[V] alternatively, is generated and measured by an oscilloscope.
   A D/A converter is utilized to output analog voltage.
   
   
2. Materials
   • Program source of the module (rect_module.c)
   • Program source of device driver for D/A converter (A/D converter is also included)
     • header file: adc.h
     • driver body: adc.c
   • Makefile
   
   
   
3. Compilation of the module
   To compile the module, simply type `make' on kterm window such as:

   % make
   	

   As the result, the module `rect_module.o' is generated if the compilation process is successfully completed without errors.
   
   
   
4. Installation of the module
   
   Firstly, check the modules now installed and confirm that there is no real time task module:

   % lsmod
   Module                  Size  Used by    Tainted: PF 
   mbuff                   8492   0
   rtl_sched              30368   0
   rtl_fifo               10848   0 (unused)
   rtl_posixio             8052   0 [rtl_fifo]
   rtl_time                7084   0 [rtl_sched rtl_posixio]
   rtl                    21232   0 [rtl_sched rtl_fifo rtl_posixio rtl_time]
   vmnet                  23656   6
   vmmon                  27444   0 (unused)
   	

   Next, install the module `rect_module.o' by the command `insmod' such as:

   % insmod rect_module.o
   Warning: loading rect_module.o will taint the kernel: no license
     See http://www.tux.org/lkml/#export-tainted for information about tainted modules
   Module rect_module loaded, with warnings
   	

   Check if the module is installed correctly:

   % lsmod
   Module                  Size  Used by    Tainted: PF 
   rect_module             1872   0 (unused) <--- This means the module is installed correctly.
   mbuff                   8492   0
   rtl_sched              30368   0 [rect_module]
   rtl_fifo               10848   0 (unused)
   rtl_posixio             8052   0 [rtl_fifo]
   rtl_time                7084   0 [rect_module rtl_sched rtl_posixio]
   rtl                    21232   0 [rtl_sched rtl_fifo rtl_posixio rtl_time]
   vmnet                  23656   6
   vmmon                  27444   0 (unused)
   	

   Now, the square wave has been occurred on D/A board.
   Check the wave form by the oscilloscope.
   
   
5. Unload the module
   
   Finally, unload the module to stop the wave generation by the command `rmmod':

   % rmmod rect_module
   	

   Confirm that the module is unloaded correctly:

   % lsmod
   Module                  Size  Used by    Tainted: PF 
   mbuff                   8492   0
   rtl_sched              30368   0
   rtl_fifo               10848   0 (unused)
   rtl_posixio             8052   0 [rtl_fifo]
   rtl_time                7084   0 [rtl_sched rtl_posixio]
   rtl                    21232   0 [rtl_sched rtl_fifo rtl_posixio rtl_time]
   vmnet                  23656   6
   vmmon                  27444   0 (unused)
   	

6. You can change the period and/or amplitude of the square wave.
   Edit the file `rect_module.c' by using the text editor xemacs.
   Then, repeat the process in this page again.