Diff: sht7X.cpp

Revision:

1:20aa2d4a28bf

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/sht7X.cpp	Wed Oct 27 15:51:27 2010 +0000
@@ -0,0 +1,180 @@
+//
+// Ian Molesworth October 2010
+// SHT 75 class
+//
+// 
+// To do:
+//
+// 
+
+#include "sht7X.h"
+
+void SHT75::reset()
+    {
+     _data.output();
+    _data = 1;                                        // data bus high
+    for (int i=0;i<12;i++)
+        {
+        _clock = 1;                                   // clock high
+        wait_us(1);
+        _clock = 0;                                   // clock lo
+        wait_us(1);
+        }
+    _clock = 1;                                   // clock high
+        wait_us(1);
+    _data  = 0;
+        wait_us(1);
+    _clock = 0;                                   // clock lo
+        wait_us(1);
+    _clock = 1;
+        wait_us(1);
+    _data  = 1;
+        wait_us(1);
+    _clock = 0;   
+        wait_us(1);
+    }
+
+void  SHT75::softReset(void)
+    {
+    _data.output();
+    start();
+    write(0x1E);
+    wait_ms(12);
+    }
+
+void  SHT75::start(void)
+    {
+    _data.output();
+    _clock = 1;
+    wait_us(1);
+    _data = 0;
+    wait_us(1);
+    _clock = 0;
+    wait_us(1);
+    _clock = 1;
+    wait_us(1);
+    _data = 1;
+    wait_us(1);
+    _clock = 0;
+    }
+
+int SHT75::readStatus(void)
+    {
+    int status;
+    status = -1;
+    start();
+    if (write(0x06) == 0)
+        status = read(1);               // read with a wait for ack
+    read(0);                            // read without the wait
+    return status;
+    }
+
+bool SHT75::write(char d)
+    {
+    auto int i;
+    _data.output();                         // bus output
+    // Writes char and returns -1 if no ACK was sent from remote
+    for (i=0;i<8;i++)
+        {
+        if (d & 0x80)
+            _data = 1;                      // data high
+        else
+            _data = 0;                      // data lo
+        // shift the data
+        d <<= 1;
+        wait_us(1);
+        _clock = 1;                         // clock high
+        wait_us(1);
+        _clock = 0;                         // clock lo
+        }
+    _data.input();                          // float the bus
+    wait_us(1);
+    _clock = 1;                             // clock high
+    wait_us(1);
+    i = _data;
+    _clock = 0;                             // clock lo
+    return i;                               // leave the bus in input mode and return the status of the ack bit read.
+    }
+
+int SHT75::read(char ack)
+    {
+    auto int i,s;
+    auto char c;
+    s = 0;
+    _data.input();                            // bus to input
+  
+    for (i=0;i<8;i++)
+        {
+        s <<= 1;
+        wait_us(1);
+        _clock = 1;                              // clock high
+        wait_us(1);
+        c = _data;                               // get the data bit
+        _clock = 0;                             // clock lo
+        if ( c )
+            s |= 1;
+        }
+
+    if (ack == 1)
+        _data = 0;                             // data lo
+    else
+        _data = 1;                             // data hi
+    _data.output();
+    _clock = 1;                                // clock lo
+    wait_us(1);
+    _clock = 0;                              // clock lo
+    _data = 1;                               // data hi
+    _data.input();
+    return s;
+    }
+
+
+// Put the current temperature into passed variable
+bool SHT75::readTempTicks(int* temp)
+{
+  int v, value;
+  start();                                  // Start a tx ( leaves data as input )
+  if (write(0x03) == 0)                     // send the read command and get an ack
+        {
+        for (v=0; v<50; v ++)               // wait for ready up to 500 ms
+            {
+            wait_ms(10);                    // 10 ms pause
+            if ( _data == 0 )               //
+                {
+                value = read(1);            // read a byte
+                value <<= 8;                // shift it in
+                value |= read(1);           // read another byte
+                read(0);
+                // transfer the value
+                 *temp = value;
+                reset();
+                return true;
+                }
+            }
+        }
+    return false;    
+    }
+
+bool SHT75::readHumidityTicks(int* humi)
+    {
+    start();
+    if (write(0x05) == 0)
+        {
+        for (int value=0; value<50; value ++)   // wait for ready up to 500 ms
+            {
+            wait_ms(10);                        //
+            if ( _data == 0 )                   //
+                {
+                value = read(1);
+                value <<= 8;
+                value |= read(1);
+                read(0);
+                *humi = value;                  // transfer the value
+                reset();
+                return true;
+                }
+            }
+        }
+   
+    return false;
+    }