Diff: AM2315.cpp

Revision:

0:770879aaecd5

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/AM2315.cpp	Thu Sep 25 18:39:45 2014 +0000
@@ -0,0 +1,60 @@
+#include "AM2315.h"
+#include "mbed.h"
+
+
+AM2315::AM2315(PinName SDA = I2C_SDA , PinName SCL = I2C_SCL ):i2c(SDA, SCL)
+{
+}
+
+// I2C Temperature and Humidity Sensor AM2315
+//
+bool AM2315::read( )
+{
+
+  char data_write[5];
+  char data_read[10];
+  int i =0;
+  for(i=0; i<8; i++)
+    data_read[i]=0;
+
+  // Wake up the sensor
+  // write single byte twice to wake up
+  // single write is not enough
+  data_write[0] = 0x00;
+  i2c.write(AM2315_ADDR,data_write,1,0); 
+  i2c.write(AM2315_ADDR,data_write,1,0);
+  
+  // Read temperature and humidity register
+  // send request to AM2315
+  data_write[0] = AM2315_REG_READ;
+  data_write[1] = 0x00;  // read from adr 0x00
+  data_write[2] = 0x04;  // read 4 bytes
+  i2c.write(AM2315_ADDR, data_write, 3, 0); // with stop
+  
+  // wait 2ms before we start to read reg
+  wait_ms(2); 
+  
+  i2c.read(AM2315_ADDR, data_read, 8, 1);
+
+  if (data_read[0] != AM2315_REG_READ) 
+    return false;
+  // check numbers of bytes read
+  if (data_read[1] != 4) 
+    return false; 
+    
+  humidity = data_read[2];
+  humidity *= 256;
+  humidity += data_read[3];
+  humidity /= 10;
+  
+  celsius = data_read[4] & 0x7F;
+  celsius *= 256;
+  celsius += data_read[5];
+  celsius /= 10;
+
+  if (data_read[4] >> 7) 
+    celsius = -(celsius);
+
+  return true;
+}
+