Diff: ds1621.cpp

Revision:

0:20bfb7df0470

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/ds1621.cpp	Fri Jul 06 20:51:31 2012 +0000
@@ -0,0 +1,142 @@
+#include "ds1621.h"
+
+DS1621::DS1621(I2C* _interface, unsigned char _address): i2c(_interface), address(_address) {
+    conversion_busy=false;
+    LastTemp=0.0;
+    StartConversion(false);
+
+    printf("Searching for I2C devices...\n");
+
+    int count = 0;
+    for (int address=4; address<256; address+=2) {
+        if (!i2c->write(address, NULL, 0)) { // 0 returned is ok
+            printf(" - I2C device found at address 0x%02X\r\n", address);
+            count++;
+        }
+    }
+    printf("%d devices found\r\n", count);
+}
+
+// Set configuration register
+void DS1621::SetConfig(unsigned char cfg) {
+    char data[2];
+    data[0]=ACCESS_CONFIG;
+    data[1]=cfg;
+    i2c->write(address,data,2);
+}
+
+// Read a DS1621 register
+unsigned char DS1621::ReadReg(unsigned char reg) {
+    char data[1];
+    data[0]=reg;
+    i2c->write(address,data,1,true);
+    i2c->read(address,data,1);
+    return (data[0]);
+}
+
+// Sets temperature limit
+// -- works only with ACCESS_TL and ACCESS_TH
+void DS1621::SetLimit(unsigned char reg, float temp) {
+    if (reg == ACCESS_TL || reg == ACCESS_TH) {
+        char data[3];
+        data[0]=reg;
+        if (temp <0.0) {
+            temp = ceil(temp * 2.0 - 0.5) / 2.0; //round to 1/2 degree
+            if (floor(temp) < temp ) { // check for extra half
+                data[1]=(~char(temp * -1.0)); //one's complement
+                data[2]=0x80; // -25.5 = -26 + 0.5
+            } else {
+                data[1]=(~char(temp * -1.0)) + 1; //two's complement
+                data[2]=0;   // -25 = -25
+            }
+        } else {
+            temp = floor(temp * 2.0 + 0.5) / 2.0; //round to 1/2 degree
+            data[1]=char(temp); //whole degrees
+            if (ceil(temp) > temp) { // check for extra half
+                data[2]=0x80;
+            } else {
+                data[2]=0x00;
+            }
+        }
+        i2c->write(address,data,3);
+        wait_ms(10);
+    }
+}
+
+// Start/Stop DS1621 temperature conversion
+void DS1621::StartConversion(bool start) {
+    char data[1];
+    if (start == true) {
+        data[0]=START_CONVERT_T;
+        i2c->write(address,data,1);
+    } else {
+        data[0]=STOP_CONVERT_T;
+        i2c->write(address,data,1);
+    }
+}
+
+// Reads temperature or threshold
+// -- works only with READ_TEMPERATURE, ACCESS_TL, and ACCESS_TH
+// -- DS1621 must be in continouis mode and started for the actual temperature
+bool DS1621::GetTemp(unsigned char reg, float *Temp) {
+    unsigned char data[2];
+    float Tc;
+
+    if (reg == READ_TEMPERATURE || reg == ACCESS_TL || reg == ACCESS_TH) {
+        ReadChipTemp(reg,data);
+
+        Tc=float(data[1]>>7) * 0.5;     // decimal part = +0.5 if bit7=1
+
+        if (data[0] >= 0x80) {          // negative? -> make two's complement
+            *Temp = float((char (~data[0])+1)*-1) + Tc;
+        } else {
+            *Temp = float(data[0])+ Tc;
+        }
+        return (true);
+    }
+    return (false);
+}
+
+// Read high resolution temperature
+// -- returns temperature in 1/100ths degrees
+// -- DS1620 must be in 1-shot mode
+bool DS1621::GetHResTemp(float *Temp) {
+
+    if (conversion_busy==false) {
+        SetConfig(ONESHOT);
+        StartConversion(true);               // initiate conversion
+        conversion_busy=true;
+        *Temp = LastTemp;
+        return (false);
+    }
+
+    if (!(ReadReg(ACCESS_CONFIG) & DONE)) {
+        *Temp = LastTemp;
+        return (false);
+    } else {
+        unsigned char data[2];
+        // get the results
+        ReadChipTemp(READ_TEMPERATURE,data);        // get whole degrees reading
+        float cRem = (float)ReadReg(READ_COUNTER); // get counts remaining
+        float cSlope = (float)ReadReg(READ_SLOPE);  // get counts per degree
+        if (data[0] >= 0x80) {          // negative? -> make two's complement
+            LastTemp = float((char (~data[0])+1)*-1);
+        } else {
+            LastTemp = float(data[0]);
+        }
+        LastTemp = LastTemp - 0.25 + (cSlope - cRem)/cSlope;
+        conversion_busy=false;
+        *Temp = LastTemp;
+        return (true);
+    }
+
+}
+
+void DS1621::ReadChipTemp(unsigned char reg, unsigned char *data) {
+    if (reg == READ_TEMPERATURE || reg == ACCESS_TL || reg == ACCESS_TH) {
+        char cmd[1];
+        cmd[0]=reg;
+        i2c->write(address,cmd,1,true);
+        i2c->read(address, (char *)data, 2);
+    }
+}
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