Diff: SHTxx/shtlib.cpp

Revision:

0:55f2866e9c0c

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/SHTxx/shtlib.cpp	Tue May 27 15:01:13 2014 +0000
@@ -0,0 +1,47 @@
+#include "shtlib.h"
+
+int sht_writefile(SHT75 sht,float *ptr_temperature,float *ptr_humidity) {
+    float humi_f,rh_lin,rh_true;           // working registers for Illustration purposes
+    int t;                                // temporary store for the temp ticks
+    int h;                                // temp store for the humidity ticks
+    sht.readTempTicks(&t);
+    *ptr_temperature = ((float)(t) * SHT_D2) + SHT_D1;
+    sht.readHumidityTicks(&h);
+    humi_f = (float)(h);
+    rh_lin = SHT_C3 * humi_f * humi_f + SHT_C2 * humi_f + SHT_C1;
+    rh_true=(((*ptr_temperature/100)-25)*(SHT_T1+SHT_T2*humi_f)+rh_lin);
+    if (rh_true>100)rh_true=-1;                            //cut if the value is outside
+    if (rh_true<1)rh_true=-1;                                //the physical possible range
+    *ptr_humidity = rh_true;
+    return 0;
+}
+
+
+int sht_init(SHT75 sht, const char *hwAddr, char *text_temp, char *text_humi) {
+    int t;
+    char shtcode[9];
+    sht.reset();
+    if (sht.readTempTicks(&t)==true) {
+        shtcode[7]=hwAddr[5];
+        shtcode[6]=hwAddr[4];
+        shtcode[5]=hwAddr[3];
+        shtcode[4]=hwAddr[2];
+        shtcode[3]=hwAddr[1];
+        shtcode[2]=hwAddr[0];
+        shtcode[1]=0x00;
+        shtcode[0]=0x80;    //famille SHT_temp
+        shtcode[8]=crc8((uint8_t*)&shtcode[0],8);
+        sprintf(text_temp,"%02X%02X%02X%02X%02X%02X%02X%02X%02X",
+                shtcode[0], shtcode[1], shtcode[2],
+                shtcode[3], shtcode[4], shtcode[5],
+                shtcode[6], shtcode[7], shtcode[8]);
+        shtcode[0]=0x81;    //famille SHT_humi
+        shtcode[8]=crc8((uint8_t*)&shtcode[0],8);
+        sprintf(text_humi,"%02X%02X%02X%02X%02X%02X%02X%02X%02X",
+                shtcode[0], shtcode[1], shtcode[2],
+                shtcode[3], shtcode[4], shtcode[5],
+                shtcode[6], shtcode[7], shtcode[8]);
+        return true; //sht present
+    }
+    return false;//sht absent
+}
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