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AD9957 Recommended for New Designs
The AD9957 functions as a universal I/Q modulator and agile upconverter for communications systems where cost, size, power consumption, and dynamic performance...
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How to write successfully user data to RAM in AD9957

		
	
				

			

									
					    bsalski
					
							

            
            			
				
									
											
			
			
				
			
			
			    	
			                    
                
				                on Dec 5, 2016 
				
			
			
		

		
		                     
				
        		

		    
		    		    
		    			

			    
Hi,

 
It seems that this issue has already been raised at this forum. Unfortunately, even though I tried to follow exactly the suggested steps I couldn't get the data successfully delivered to the memory in AD9957. In particular, I'm not sure how to organize the sequence of signals during RAM loading. I tried as follows:

 
1. CS = low

 
2. Send RAM address (0x16)

 
3. Send N 32-bit words one after another (with I/O_Update issued after each of them)

 
4. CS = high

 
Sometimes, I see that the first bit is changed but all the other are unaffected by the above procedure.

 
I will appreciate any suggestions.

 
Bartek

			

			
									
		                             
                        

    

                                            
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    •  Analog Employees  
    
            
						
                            
            
            				
            
                on Dec 9, 2016 9:45 PM
            
            
						
			            		
    
		
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    RAMdata appears to be a structure with two components: bits31_16 and bits15_0.
    
 
    I see no problem with bits15_0, as these are being forced to 0x0000.
    
 
    However, y is a signed number. It must, in fact, be a 16b signed integer, otherwise there will be an inconsistency. Because the "y" operation includes floats and integers, you should verify that the y values reflect the 16b hex values you expect them to be. You could be suffering from a data format/casting issue.
    
			
    

		
			
	      

		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
						
				
						
				
				
		
		
    
			
		
    
	
    

    

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    •  Analog Employees  
    
            
						
                            
            
            				
            
                on Dec 9, 2016 9:45 PM
            
            
						
			            		
    
		
										0
					
	
    

		
		
    
		
    
                                
                                                            
    
					
    RAMdata appears to be a structure with two components: bits31_16 and bits15_0.
    
 
    I see no problem with bits15_0, as these are being forced to 0x0000.
    
 
    However, y is a signed number. It must, in fact, be a 16b signed integer, otherwise there will be an inconsistency. Because the "y" operation includes floats and integers, you should verify that the y values reflect the 16b hex values you expect them to be. You could be suffering from a data format/casting issue.
    
			
    

		
			
	      

		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
						
				
						
				
				
		
		
    
			
		
    
	
    

    

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