Iron - DACs and ADCs.

Track: Between da Earth and da Sky  
Author: Macros/Kotlas town. Summer 2001  
-------------------------------------------------------

  Well... Considering that until recently
we had absolutely no time
information on ADCand DAC's, then I decided
fill this gap, and downloaded from the Internet
several old newspapers, in
which, according to my assumptions, should
there was this info.  And I was not mistaken.
By uploading several text files to
disk, later I collected something from them,
which you will see below. Basically, this
enough information to understand and
development of own circuits ADCand DAC's.
I repeat that until recently we
they knew almost nothing about this anymore, so
don't make square eyes :)       
  Along the way I deleted every
extraneous garbage, like that description
connecting this junk to the musiccoprocessor.  My processor is different
busy ;)                                 
 First comes  a description of the ADC chip.
Well, let's go...                    

  Pin 15 is for selecting mode
transformations.   If the pin is 15
logical 0, then the ADC operates in
unipolar mode. To switch the ADC
in bipolar mode, pin 15 should be
free.  Control signals: pin 11
ADC: signal suppression/conversion.
1-quenching, 0-conversion.    After
receiving an ADC conversion signal
starts converting analog
signal to digital form using
successive approximation.  Therefore
the digital code at the ADC output appears with
small delay: approximately ZOmks or
about 11 cycles of Z-80.  Need to take into account
this circumstance, or interrogate the ADC
by the readiness signal (17 pin of the ADC). When
logical 0 on this pin of the ADC is ready and
You can remove bytes to the data bus. After
how the ADC outputs the "ready" signal
you need to read the byte in RAM, after which
reset the ADC (see above) and send a signal
transformations. Otherwise, the ADC output will be
sit the old byte and you will fill the RAM
with just one digital count.For the ADC to work, -15 is required (or, at
at worst, -12 ) volts.                

 data readiness                       
 ------------------+                     
                   |                     
       К111ЗПВ1А |                     
      +---------+ |                     
 -18--+D0|  | __|17|                     
 -1---+D1|  | DR+--+ ++-----< Login 
 -2---+D2|  |>0<+--+-15--+ || R1-4.7k    
 -3---+D3|  |OVA+--+14 -+-|#            
 -4---+D4|  | AI+--13------+|            
 -5---+D5|  |-U2+--12-------+-----< -15v 
 -6---+D6|  |+U2+--10------------< + 5v 
 -7---+D7|  |OVD+--16--+---------< General 
 -8---+D8|  |___|     -+-                
 -9---+D9|  |G/P+--11-+                  
      +---------+ |                  
 |                  
 ---------------------+                  
 quenching/conversion                  

 Technical data of this ADC:
maximum conversion frequency -
44000 Hz.  With the appropriate driver,
conversion time 1 byte: at frequency
50 Hz signal for more than 30 µs (10/11
Z-80 cycles). Supply voltage: +5 V,
4 mA; -15 V, 15 mA. Input voltage
in modes: unipolar - 0...11 V,
bipolar: -5.5V to +5.5V.         


                DACs ;)                 

IT IS STRICTLY PROHIBITED TO LEAVE
FREE DIGITAL DAC INPUTS! Otherwise DAC
fails immediately!             

    (OPTION-1, with unipolar power supply) 
                               C1        
         KPS72PA1A +--+--++-< Exit   
 +---------+ |R1|R2             
   -13--+D0|  |   |15 # # R1,R2-10k.
   -12--+D1|  |Uon+---+ -+- C1-1uF.  
   -11--+D2|  |   |16                    
   -10--+D3|  |Roc+--                    
   --9--+D4|  | I1+-1-+-< +5 V DAC       
   --8--+D5|  |   |   |                  
   --7--+D6|  |+Un+-14+                  
   --6--+D7|  | I2+-2-+-< Common DAC      
   --5--+D8|  |   |   |                  
   --4--+D9|  | 0V+-3-+                  
        +---------+ +                  

  (OPTION-2, with bipolar power supply)   

    KPS72PA1A                            
   +--------+                            
-13+D0| |   |15 DA1-K1CHOUDb Power supply:    
-12+D1| |Uon+--+---------+--<+6..15B.    
-11+D2| |   |14|         |               
-10+D3| |+Un+--+ DA1 7               
--9+D4| |   |1 +-+-+ C1-1mf. 
--8+D5| |I-1+--------2-. A +-6----+-++-< 
--7+D6| |   |16 +---3-+ |      |      
--6+D7| |Roc+--+ # R1 +-+-+ Pit. |      
--5+D8| |   |2 | + 5K. 4|-6..15B.|      
--4+D9| |I-2+--|         +------< |      
   |  | |   |3 +------------------+      
   |  | |0Vn|--+------< General            
   +--------+ +                         


When connecting kovoks to ports,
check if they are pulled up to +5 V, if
no, you'll have to solder eight
resistors (1...10k) per port
(D0..D7).                                
  The second circuit has bipolar power supply from
6 to 15 volts (but always the same
in both shoulders). Operational amplifier
can be replaced with almost anything
observing the pinout of the analogue.              

  Well, this is for you, just in case, in case
why will you connect via BB-x...    

 Control word layout for BBSS
(#7F):                                   

 D0 - port C (lower 4 bits): 1-input,
0-output.                                 
 D1 - port B: 1-input, 0-output.           
 D2 - group B mode: 0-mode '0', 1-re-
press '1'.                                 
 D3 - port C (high 4 bits): 1-input,
0-output.                                 
 D4 - port A: 1-input, 0-output.           
 Bits D5, D6 determine the operating mode
PPRI:                                    
 D5-0, D6-0: mode '0'; D5-0, D6-1: mode
'1';  D5-1, D6-0: mode '2'; D5-1, D6-1:
mode '2'.See the reference manual for more details.
 Bit D7 must be at 1.