Controlling LEDs on FX2LP board

Version 1
    Question: How to light LED's on the FX2LP board from the code to have software test points?

     

    Answer:

    A portion of the GAL (U2) decodes 8051 reads to certain external memory addresses to turn the four general-purpose indicators D2-D5 on and off. The following table shows the external 8051 addresses which are read to turn them on and off. Note that the four jumpers above the LEDS must be installed to use this feature. These jumpers connect the LEDS to four GAL outputs.

     

     

     

                 
       

         Indicator

      
                                                                                                 
       

        

      
       

         Turn ON by reading

      
       

         Turn OFF by reading

      
       

         D2

      
       

         0x88--

      
       

         0x80--

      
       

         D3

      
       

         0x98--

      
       

         0x90--

      
       

         D4

      
       

         0xA8--

      
       

         0xA0--

      
       

         D5

      
       

         0xB8--

      
       

         0xB0--

      

     

     

    The low address byte is “don’t care”. By this means one can very efficiently add software test points.