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main spi with loop back.c

@@ -0,0 +1,84 @@
+
+
+//SPI with LOOP Back
+
+#include <stdint.h>
+
+#define RCGCGPIO  (*((volatile unsigned long *)0x400FE608))
+#define GPIOAFSEL (*((volatile unsigned long *)0x40004420))
+#define GPIODEN   (*((volatile unsigned long *)0x4000451c))
+#define GPIOPCTL  (*((volatile unsigned long *)0x4000452c))
+#define RCGCSSI   (*((volatile unsigned long *)0x400fe61c))
+#define SSICR1    (*((volatile unsigned long *)0x40008004))
+#define SSICPSR   (*((volatile unsigned long *)0x40008010))
+#define SSICR0    (*((volatile unsigned long *)0x40008000))
+#define SSISR     (*((volatile unsigned long *)0x4000800c))
+#define SSIDR     (*((volatile unsigned long *)0x40008008))
+#define GPIODIR   (*((volatile unsigned long *)0x40004400))
+#define GPIODATA  (*((volatile unsigned long *)0x40004000))
+#define SSICC     (*((volatile unsigned long *)0x40008FC8))
+#define GPIOPDR   (*((volatile unsigned long *)0x40004514))
+
+
+void SPI_init(void)
+{
+    RCGCSSI  |= 0x1;  // enable spi clock
+    RCGCGPIO |= 0x1; // enable gpio clock
+    GPIOAFSEL |= 0x3c;  // PA[5:2] alternate
+    GPIOPCTL  |= 0x222200; // pctl
+    GPIODEN   |= 0x3c;
+    GPIOPDR   |= 0x08;
+    //pull up is missed
+    // ssi config
+    SSICR1 &= ~0x02; //disable sse bit
+    SSICR1 |= 0x00; // master
+    SSICC |=0x0;    //clock mode
+    SSICR0 |= 0x07;  //8-bit data frame
+    SSICR1 |= 0x03;  // enable and LBM
+
+     }
+
+
+
+uint8_t tx (uint8_t data);
+uint8_t rx ();
+
+
+int main(void) {
+    uint8_t  DR=0 ;
+    uint8_t  REC=0 ;
+
+    SPI_init();
+
+    while (1){
+
+        DR= tx(0xAA);
+
+        REC= rx();
+    }
+
+
+	return 0;
+}
+
+
+
+uint8_t tx (uint8_t data)
+  {  SSIDR = data;
+    while((SSISR & 2)==0);  //wait until TNF bit is equal 1
+     return SSIDR;
+    }
+
+  uint8_t rx ()
+  {  uint8_t data =0;
+      while((SSISR & 4)== 1);  //wait until RNE bit is equal 0
+     data= SSIDR+1;
+       return data;
+  }
+
+  /*uint8_t SPI_TRSF (uint8_t data)
+     {
+      SSIDR = data;
+      while (!(SSISR & 0x04));
+      return SSIDR;
+     }*/