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MAX32655 Recommended for New Designs
The MAX32655 microcontroller (MCU) is an advanced system-on-chip (SoC) featuring an Arm® Cortex®-M4F CPU for efficient computation of complex functions...
MAX32655 on Analog.com

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getchar and scanf functions in MAX32655FTHR with CFS/VSC

		
	
				

			

									
					    Satoru
					
							

            
            			
				
									
											
			
			
				
  •  Analog Employees  

			
			
			    	
			                    
                
				                on Sep 27, 2025 
				
			
			
		

		
		                    	    

        	    
Thread Summary

                The user is experiencing issues with getchar() and scanf() functions when trying to modify SD-ADC settings on the MAX32655FTHR through the VS Code serial console. The final answer confirms that these functions should work with the Maxim SDK's stdio.c implementation, which redirects standard I/O to the UART. The user needs to ensure the serial console sends a carriage return (CR) when Enter is pressed, as the _read() function waits for CR to signal the end of input.
                        	    

                
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Category: Software

    		        		            		    
Product Number:  MAX32655  

    		        		        		        
Software Version: 1.1.0

    		    		    

		    		    
		    			

			    
Hi,


I am newcomer for MAX32655 and trying to communicate with SD-ADC using MAX32655FTHR.


My program works almost OK and I am thinking the program to work modifying SD-ADC's setting through VS code serial console.


printf function works OK and its characters appear on the serial console.


But if I use getchar function in my code, the character puts to the serial console can't obtained in my code.


Can getchar and scanf use in the environment and could you suggest me how to use these function if it is possible?


Regards,


Satoru

			

			
									
		                             
                        

    

                                            
                 Ultra Low Power Microcontrollers
                
                                                    
                 software
                
                                                    
                 microcontrollers
                
                                                    
                 1.1.0
                
                                                    
                 MAX32655
                
                                
            

    
    
		


				
				        
        		

			
						
									
												
			
			
                        
                                    
                        
                        
                        
            
			            
						
						
			
			
			
			
		


        
        
        
    
					

			





















	

	

					



			








	
	
	
	



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    •  Analog Employees  
    
            
						
                            
            
            				
            
                on Oct 6, 2025 4:34 AM
            
            
						
			            		
    
		
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    Hi Satoru,
    

    The Maxim SDK (msdk) already includes a stdio.c implementation that redirects standard I/O functions like printf(), scanf(), and getchar() to the UART interface. This file provides the necessary low-level _read() and _write() functions, allowing seamless communication through the serial console.
    

    By default, the _read() function waits for a carriage return (\r) to signal the end of input. This means that:
    

      

    • 

      You do not need to modify _read() yourself — it's already implemented correctly in the SDK.
      

      • 

    • 

      UART must be initialized properly using MXC_UART_Init() — it's already initialized correctly because you can see the printf() outputs.
      

      • 

    • 

      Your serial console (e.g. Serial Monitor extension by Microsoft in VS Code) must send at least a carriage return (CR) when you press Enter.
      

        

      • 

        Sending CR+LF also works, but CR alone is sufficient.
        

        • 

      

      • 

    

    Once these conditions are met, scanf() and getchar() will function as expected, allowing interactive input from the serial terminal.
    

     
    

    Kind regards,
    

    Haluk
    
			
    

		
			
	      

		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
						
						
						
				
				
		
		
    
			
		
    
	
    

    

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    •  Analog Employees  
    
            
						
                            
            
            				
            
                on Oct 6, 2025 4:34 AM
            
            
						
			            		
    
		
										+1
					
	
    

		
		
    
		
    
                                
                                                            
    
					
    Hi Satoru,
    

    The Maxim SDK (msdk) already includes a stdio.c implementation that redirects standard I/O functions like printf(), scanf(), and getchar() to the UART interface. This file provides the necessary low-level _read() and _write() functions, allowing seamless communication through the serial console.
    

    By default, the _read() function waits for a carriage return (\r) to signal the end of input. This means that:
    

      

    • 

      You do not need to modify _read() yourself — it's already implemented correctly in the SDK.
      

      • 

    • 

      UART must be initialized properly using MXC_UART_Init() — it's already initialized correctly because you can see the printf() outputs.
      

      • 

    • 

      Your serial console (e.g. Serial Monitor extension by Microsoft in VS Code) must send at least a carriage return (CR) when you press Enter.
      

        

      • 

        Sending CR+LF also works, but CR alone is sufficient.
        

        • 

      

      • 

    

    Once these conditions are met, scanf() and getchar() will function as expected, allowing interactive input from the serial terminal.
    

     
    

    Kind regards,
    

    Haluk
    
			
    

		
			
	      

		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
						
						
						
				
				
		
		
    
			
		
    
	
    

    

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