Direct Digital Synthesis (DDS) on the GA144 (Part 2)

I found out why I couldn't get two nodes to run with my start script. I was too impatient. I'd forgot that I had the serial connection to the Eval board running at only 115kbps. The command to install the code in the various nodes visits all the nodes and it was simply taking forever and I assumed the IDE had stalled.

Anyway, I took the delay word out of node 617 and put a simple counting loop in node 616 which asserts the 'right' port (which is common to the nodes) when the loop finishes. Then node 617 waits till its 'right' port is asserted, then continues with code to load the sine value into the DAC port.

This makes the sine wave much more stable. With the value of 500 in the go loop the sine wave is precisely 799.9Hz and stays rock solid on that value. I doubt if a crystal would make it much more stable but I'll try a crystal next.

With the following code, make sure 866 and 868 are loaded in block 200 to ensure they are compiled. Then '870 load' will start the app.

866 list 
sine wave generator,
617 node 0 org,
0 , 40 , 80 , 120 , 170 ,,
220 , 280 , 370 , 511 ,,
hart 3300; -.00433 .07943
            -.64589 1.57079,
cos tri 2* 2* . triangle
    dup *. 2 poly
   -281 , 5203 , -42329 , 37407 ,
   push drop pop *. + ;
scaled 2/ 8000 . +
       8191 12 interp ;
dac! io b! 155 or !b ;
start 1f 128 phaseinc
   dup dup or
   begin
   dup cos scaled
   synch right b! @b drop
   dac!
   over . +
   end


868 list 
timer count cycles,
616 node 0 org,
hold for . . unext ;,
ms for 27063
     for . . . unext
  next;
start 08 right b! 1 ms,
go 500 hold !b go ;

870 list 
sine wave loader
host load loader load
using default ide paths
kill boots
0 708 hook 0 -hook
setup application
616 +node 616 /ram 8 /p
617 +node 617 /ram 1f /p
visit sine path
panel pause 2 ship