Revision 0:8b2fe06d6a2e, committed 2014-05-30

Comitter:

trichards1138

Date:

Fri May 30 18:31:15 2014 +0000

Commit message:

Final code for One Wire Thermometer MBED control program not using MBED library

Changed in this revision

diff -r 000000000000 -r 8b2fe06d6a2e main.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Fri May 30 18:31:15 2014 +0000
@@ -0,0 +1,228 @@
+#include "owInterface.h"
+#include <stdio.h>
+
+unsigned char write_data[3];
+unsigned char address[8];
+int searchJunction;        // so we can set to it -1 somewhere
+
+int owReset() 
+{
+    int result = 0;    // sample presence pulse result
+    clr_owPin();
+    delay_us(480);
+    set_owPin();
+    read_owPin();   //just to set direction
+    delay_us(70);
+    result = read_owPin();
+    delay_us(410);   
+    return result;
+}
+
+void writeBit(int bit)
+{
+    bit = bit & 0x01;
+    
+    if (bit)
+    {
+        // Write '1' bit
+        clr_owPin();
+        delay_us(6);
+        set_owPin();
+        read_owPin();
+        delay_us(64);
+    }
+    else
+    {
+        // Write '0' bit
+        clr_owPin();
+        delay_us(60);
+        set_owPin();
+        read_owPin();
+        delay_us(10);
+    }
+}
+//
+// Read a bit. Port and bit is used to cut lookup time and provide
+// more certain timing.
+//
+int readBit() 
+{
+    int result;    
+    clr_owPin();
+    delay_us(6);
+    set_owPin();
+    read_owPin();
+    delay_us(9);
+    if( read_owPin() )
+        result = 1;
+    else
+        result = 0;
+    result = read_owPin();
+    delay_us(55);
+       
+    return result;
+}
+
+//
+// Write a byte. The writing code uses the active drivers to raise the
+// pin high, if you need power after the write (e.g. DS18S20 in
+// parasite power mode) then set 'power' to 1, otherwise the pin will
+// go tri-state at the end of the write to avoid heating in a short or
+// other mishap.
+//
+void ow_writeByte(int data) 
+{
+    // Loop to write each bit in the byte, LS-bit first
+    for (int loop = 0; loop < 8; loop++)
+    {
+        writeBit(data & 0x01);
+        
+        // shift the data byte for the next bit
+        data >>= 1;
+    }
+}
+
+//
+// Read a byte
+//
+int ow_readByte() 
+{
+    int result = 0;
+    
+    for (int loop = 0; loop < 8; loop++)
+    {
+        // shift the result to get it ready for the next bit
+        result >>= 1;
+        
+        // if result is one, then set MS bit
+        if (readBit()) result |= 0x80;
+    }
+    
+    return result;
+}
+
+void resetAndSelectRom(void)
+{
+    if( owReset() )
+        printf("DS18D20 device not present\r\n");
+    else {
+        ow_writeByte( 0xCC );   //Only dealing with one
+    }   //device, so use "SkipROM" command
+}
+
+void Get_Temp(void)
+{
+    unsigned char data[10];
+    bool signBit = false;
+    resetAndSelectRom();    //
+    ow_writeByte( 0x44 );   //Convert
+    while( !read_owPin() )
+        delay_us(1000*5);  //delay 5 Millisec
+    resetAndSelectRom();
+    ow_writeByte( 0xBE );   //read scratchpad
+ //   printf("read = ");
+    for (int i = 0; i < 9; i++) 
+    {               
+        // we need all bytes which includes CRC check byte
+        data[i] = ow_readByte();
+ //       printf("%x ", (int)data[i]);
+    }
+ //   printf("\r\n");
+       
+    if (data[1] & 0x80) signBit = true;
+        
+    int read_temp = (data[1] << 8) + data[0];
+    if (signBit)
+    {
+        read_temp = (read_temp ^ 0xFFFF) + 1;    // two's complement
+        read_temp *= -1;
+    }
+    
+    int resolution = (data[4] & 0x60) >> 5; // mask off bits 6,5 and move to 1,0
+    switch (resolution)
+    {
+        case 0:    // 0.5 deg C increments
+            read_temp &= 0xFFF8;                // bits 2,1,0 are undefined
+            printf("9 bit resolution ...\r\n");
+            break;
+        case 1:     // 0.25 deg C increments
+            read_temp &= 0xFFFC;                // bits 1,0 are undefined
+            printf("10 bit resolution ...\r\n");
+            break;
+        case 2:  // 0.125 deg C increments
+            read_temp &= 0xFFFE;                // bit 0 is undefined
+            printf("11 bit resolution ...\r\n");
+            break;
+        case 3:  // 0.0625 deg C increments
+            printf("12 bit resolution ...\r\n");
+            break;
+    }
+    float realTemp = (float)read_temp/16 ;
+    float realTempF = ((realTemp * 9) / 5) + 32;
+                 
+    printf("Temperature in deg C: %f \r\n", realTemp); 
+    printf("Temperature in deg F: %f \r\n", realTempF);
+}     
+    
+void set_Resolution(int res)
+{
+    // as the write to the configuration register involves a write to the
+    // high and low alarm bytes, need to read these registers first
+    // and copy them back on the write
+    
+    unsigned char read_data[9];
+    resetAndSelectRom();
+    ow_writeByte( 0xBE );   //read scratchpad
+   // pc.printf("read = ");
+    for (int i = 0; i < 9; i++) 
+    {               
+        // we need all bytes which includes CRC check byte
+        read_data[i] = ow_readByte();   //Get the 8-bytes +CRC
+    //    pc.printf("%x ", (int)read_data[i]);
+    }
+   // pc.printf("\r\n");
+    
+    // copy alarm and config data to write data
+    for (int k = 2; k < 5; k++)
+    {
+        write_data[k - 2] = read_data[k];
+    }
+    int config = write_data[2]; //Get current config
+    config &= 0x9F;     //Isolate the resolution bits
+    config ^= (res << 5);   //Set the new ones
+    write_data[2] = config; //write it in the array to send
+    
+    resetAndSelectRom();
+    ow_writeByte( 0x4E );   //write scratchpad
+    for (int k = 0; k < 3; k++)
+    {
+       ow_writeByte(write_data[k]); //Write back out the 
+    }                           //first three bytes to set Resol
+    owReset();      //reset to end transaction early
+}
+
+int get_res(void)
+{
+    int choice=0;
+    printf("Resolution choices are: 9-bit=0, 10-bit=1, 11-bit=2, 12-bit=3\r\n"); 
+    printf("What resolution would you like (0,1,2,3):\r\n");
+    choice = getchar() - 48;  //get input char and turn it into an int
+    if( (choice >= 0) && (choice < 4) )  //is it within scope?
+        return choice;  //yes, return it
+    else {
+        printf("Invalid Selection:  I've selected 12-bit for you\r\n");
+        return 3;       //no, return default (12-bit)
+    }
+}
+
+int main(void)
+{
+    read_owPin();   //set direction input
+    init_timer();   //set up timer for 1us tick
+    set_Resolution(get_res());  //12-bit
+     while( 1 ) {
+        Get_Temp();     //Go get the temp
+        delay_us(1000*5000);    //Wait 5 sec before 
+    }                           //repeating
+}
+

diff -r 000000000000 -r 8b2fe06d6a2e owInterface.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/owInterface.h	Fri May 30 18:31:15 2014 +0000
@@ -0,0 +1,70 @@
+
+#ifndef __owInterface_h
+#define __owInterface_h
+
+//For testing the One-Wire (OW) ports below
+//#define OWPORT  1     //test port (LED)
+//#define OWPIN   20
+
+//Selects the direction and pin for the main One Wire input/output
+#define OWFIOPIN (*(volatile unsigned int *)(0x2009C000 | ((OWPORT*0x20)+0x10) | 4 ))
+#define OWFIODIR (*(volatile unsigned int *)(0x2009C000 | (OWPORT*0x20)))
+//Provides a test pin near the OW to test the OW output
+#define TESTFIOPIN (*(volatile unsigned int *)(0x2009C000 | ((TESTPRT*0x20)+0x10) | 4 ))
+#define TESTFIODIR (*(volatile unsigned int *)(0x2009C000 | (TESTPRT*0x20)))
+
+//MBED pin 25 resolves to port 2 pin 1
+#define OWPORT  2
+#define OWPIN   1
+//MBED pin 26 is near 25 for testing
+#define TESTPRT 2
+#define TESTPIN 0
+
+//Set the selected Pin to one
+void __inline__ set_owPin(void)
+{
+    OWFIODIR |= 1 << OWPIN;   //Set pin direction to output
+    OWFIOPIN |= 1 << OWPIN;   //Set pin state (1)
+}
+//Set the selected pin to zero
+void __inline__ clr_owPin(void)
+{
+    OWFIODIR |= 1 << OWPIN;   //Set pin direction to output
+    OWFIOPIN &= ~(1 << OWPIN);//Clear pin state (0)
+}
+//Reads the pin, but also sets direction to input
+int __inline__ read_owPin(void)
+{
+    OWFIODIR &= ~(1<<OWPIN);  //Set pin direction to input
+    return ((OWFIOPIN>>OWPIN)&0x1);   //Return the pin state
+}
+//Test pin to see the write bits on the OW
+int __inline__ read_testPin(void)
+{
+    TESTFIODIR &= ~(1<<TESTPIN);
+    return ((TESTFIOPIN>>TESTPIN)&0x1);
+}
+//Timer control registers
+#define TIMER3_TCR  (*(volatile unsigned int *)(0x40094004))
+#define TIMER3_TC   (*(volatile unsigned int *)(0x40094008))
+#define TIMER3_PR   (*(volatile unsigned int *)(0x4009400C))
+#define TIMER3_CTCR (*(volatile unsigned int *)(0x40094070))
+#define PWRCTL_PCONP (*(volatile unsigned int *)(0x400FC0C4))
+#define SYS_CLK     96000000
+
+void init_timer(void)
+{
+   PWRCTL_PCONP |= 1<<23;   //Power up timer3
+   TIMER3_CTCR = 0;         //set to timer (not counter)
+   TIMER3_TCR = 0x2;        //Put timer in reset
+   TIMER3_PR = ((SYS_CLK / 4000000) - 1); //One us per tick
+   TIMER3_TCR = 0x1;        //enable timer
+}
+//Delay for "dly_us" us (microSeconds)
+void __inline__ delay_us(unsigned int dly_us)
+{
+    unsigned int startt = TIMER3_TC;
+    while ((TIMER3_TC-startt) < dly_us) ;
+}
+
+#endif
\ No newline at end of file