Diff: main.cpp

Revision:

0:32af259f9f2a

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Sun Feb 17 00:30:29 2019 +0000
@@ -0,0 +1,70 @@
+
+// program used to read SPI 12 bit Encoder AMT203-V in steps of 16
+#include "mbed.h"
+
+Serial pc(USBTX, USBRX); // tx, rx
+SPI EncoderSpi(p5, p6, p7);//Mosi Miso Sclk
+DigitalOut cs(p8); //Chip select
+
+uint16_t EncoderByteData = 0;
+uint16_t Encoderposition_last = 0;
+uint8_t temp[2];
+uint16_t Steps;
+void wait_ms(int us);
+
+
+uint8_t SPI_T (uint8_t SPITransmit)//Repetive SPI transmit sequence
+{
+    uint8_t SPI_temp = 0;  //vairable to hold recieved data
+    cs=0;     //select spi device
+    SPI_temp = EncoderSpi.write(SPITransmit);//send and recieve
+    cs=1;//deselect spi device
+    return(SPI_temp);      //return recieved byte
+}
+
+void start()
+{
+    uint8_t recieved = 0xA5;//just a temp vairable
+    EncoderByteData  = 0;//reset position vairable 
+    cs=0;  
+    SPI_T(0x10);//issue read command     
+    wait_ms(50);//give time to read. Timmig is critical
+    
+    while (recieved != 0x10) //loop while encoder is not ready to send
+    { 
+     recieved = SPI_T(0x00); //cleck again if encoder is still working
+     wait_ms(1); //again,give time to read. Timmig is critical
+    }
+
+     temp[0] = SPI_T(0x00); //Recieve MSB
+     temp[1] = SPI_T(0x00); // recieve LSB      
+     cs=1;
+        
+     temp[0] &=~ 0xF0;//mask out the first 4 bits
+     EncoderByteData  = temp[0] << 8; //shift MSB to correct EncoderByteData in EncoderByteData message
+     EncoderByteData  += temp[1]; // add LSB to EncoderByteData message to complete message            
+     wait_ms(1);//again,give time to read. Timmig is critical
+}
+
+int main()
+{  
+    EncoderSpi.format(8,0);
+    EncoderSpi.frequency(8000000);
+    
+ while(true)
+    {
+   
+     if (EncoderByteData != Encoderposition_last) //if nothing has changed dont wast time sending position
+    {
+      Encoderposition_last = EncoderByteData ; //set last position to current position         
+    }
+     else
+    {   
+      start(); //if something has changed in position, catch it
+    } 
+        Steps = EncoderByteData;        
+       //pc.printf("Data = %d \n", EncoderByteData ); //actual byte reading
+        pc.printf("Data = %03d \n", Steps/16 );
+    }
+    
+}
\ No newline at end of file