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SPI communication- Bit Banging

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RAJPUT VIDISHA

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Hi,

I'm doing SPI Bit Banging using PIC16F1718 as slave. I could make it work but only for 1 byte i.e by using char rdata, where rdata is the buffer which stores the incoming bits. so, now i want to use int so that i can store more than 1 byte, but it's giving me errors like:

-> Operator '.' is not applicable to these operands 'rdata'
-> Internal error 'undefined aggregate'
->Internal error 'undefined struct'

I'm attaching my complete working code. I have highlighted the lines with Blue color. Please once have a look and tell me how to use int to make it work.

Code C - [expand]
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sbit CE at RB4_bit;
sbit CE_Direction at TRISB4_bit;     
[COLOR="#0000FF"]unsigned int rdata ;[/COLOR]
unsigned char data_read_flag;
int count;
unsigned char i;
 void main(){
    OSCTUNE = 0x80;
    OSCCON = 0b01110010;
              
    RXPPS = 0x17;      
    RC6PPS = 0X14;   
 
    ANSELA = 0x00;  //PORT A as Digital
    ANSELB = 0x00;
    ANSELC = 0x00;
 
    TRISA = 0b00010001;  
    TRISB = 0b00110100; 
    TRISC = 0b10000000; 
 
    IOCBN = 0X10; //Enable IOC on RB4 -VE Edge  of CE
 
    INTCON = 0x88;
 
      UART1_Remappable_Init(9600);
       do{
         if(data_read_flag == 1){
           PORTC.B6 = ~PORTC.B6;
          }
       }while(1);
  }
  
 
void interrupt(){
 
//case for falling edge of CE       //IOCBN4_bit
 
if(IOCBN4_bit && IOCBF4_bit && IOCIF_bit) //If RB4 Lower Edge is detected ,IOCBF4_bit is 1
{         
 IOCBP5_bit = 1;  // enabling interrupt on rising edge of RB5 i.e., CLK
 IOCBP.B4 = 1;  // enabling interrupt on rising edge of CE
 IOCBN4_bit = 0; //Disabling the interrupt on CE -ve Edge
 IOCBF4_bit = 0; //Disabling RB4 flag bit
 IOCIF_bit = 0;  //Disabling IOC flag bit
   count = 0;
 
 }
if(IOCBF5_bit && IOCIF_bit )  //If RB5 Rising Edge Detected
 {       
 IOCBF5_bit = 0; //Disabling RB5 Flag bit
 IOCIF_bit = 0;  //Disabling IOC flag bit
 
       count = count + 1;
  [COLOR="#0000FF"] rdata.B0 = PORTA.B0; //Reading Data on RA0 pin[/COLOR]
   if(count<8){
   rdata = (rdata << 1) ;  //shifting the incoming bits to the left
         }                                                                                                                                                                                                                                                                                                                                                           
 
 }
 
 
 if( IOCBP4_bit && IOCBF4_bit && IOCIF_bit)
 {
 data_read_flag = 1;
 IOCBP.B4 = 0;  //Disable IOC on Rising Edge of RB4
 IOCBP.B5 = 0;  //Disable IOC on Rising Edge of RB5
 
 IOCBN.B4 = 1; // enabling interrupt for the next transaction
 IOCBP4_bit = 0;
 IOCIF_bit = 0;
        UART1_Remappable_Write(rdata );
 
 }
 }



Regards
Vidisha
 
Last edited by a moderator:

There are no bitbang in PIC16 and PIC18.
Try this:
rdata = PORTA & 1;
And for the future. Bitbang is a different thing, not applicable to this bit-oriented operations.
 

Thanks @Easyrider83
if i use rdata = PORTA & 1;
i'm able to use int without any errors but still i'm receiving 1 byte only..
 

Never call functions like UART1_Remappable_Write(rdata ); inside interrupt.
And data_read_flag never been cleared. Only set.
 

okay..
anyways i got to know just now that SPI_Write can only write one byte so that's the reason i'm receiving only one byte.
 

Don't use SPI_Write() library function. Write your own SPI Write routine which can write 8, 16 or 32 bits as required.
 

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