Diff: TMP102.cpp

Revision:

0:8818842a3573

Child:

2:1a4fbc01a494

diff -r 000000000000 -r 8818842a3573 TMP102.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/TMP102.cpp	Fri Feb 05 17:24:06 2016 +0000
@@ -0,0 +1,85 @@
+// library implemtation file
+
+// obviously need to include the header
+#include "TMP102.h"
+
+// we now implement each of the methods listed in the header
+
+// note the TMP102:: at the beginning of the method name
+TMP102::TMP102(PinName sda, PinName scl)
+{
+    // in the constructor, we create the mbed API objects using 'new'
+    i2c_ = new I2C(sda,scl);
+    led_ = new DigitalOut(LED_RED);
+}
+
+void TMP102::init()
+{
+    i2c_->frequency(400000); // set bus speed to 400 kHz
+
+    int ack;  // used to store acknowledgement bit
+    char config_data[2];  // array for data
+    char reg = CONFIG_REG;  // register address
+
+    //////// Read current status of configuration register ///////
+
+    ack = i2c_->write(TMP102_W_ADD,&reg,1);  // send the slave write address and the configuration register address
+    if (ack)
+        error();  // if we don't receive acknowledgement, flash error message
+
+    ack = i2c_->read(TMP102_R_ADD,config_data,2);  // read default 2 bytes from configuration register and store in array
+    if (ack)
+        error();  // if we don't receive acknowledgement, flash error message
+
+    ///////// Configure the register //////////
+
+    // set conversion rate to 1 Hz - CR1 and CR2 are in the second data byte
+    config_data[1] |= (1 << 6);    // set bit 6
+    config_data[1] &= ~(1 << 7);    // clear bit 7
+
+    //////// Send the configured register value to the slave config register ////////////
+
+    // create data packet
+    char data_packet[3] = {reg,config_data[0],config_data[1]};
+
+    ack = i2c_->write(TMP102_W_ADD,data_packet,3);  // send the data packet to the slave write address
+    if (ack)
+        error();  // if we don't receive acknowledgement, flash error message
+
+}
+
+void TMP102::read_temperature()
+{
+    int ack;  // used to store acknowledgement bit
+    char data[2];  // array for data
+    char reg = TEMP_REG;  // temperature register address
+
+    ack = i2c_->write(TMP102_W_ADD,&reg,1);  // send temperature register address
+    if (ack)
+        error();  // if we don't receive acknowledgement, flash error message
+
+    ack = i2c_->read(TMP102_R_ADD,data,2);  // read 2 bytes from temperature register and store in array
+    if (ack)
+        error();  // if we don't receive acknowledgement, flash error message
+
+    int temperature = (data[0] << 4) | (data[1] >> 4);
+
+    temperature_ = temperature*0.0625F;
+}
+
+// temperature accessor method
+float TMP102::get_temperature() 
+{
+    read_temperature();
+    return temperature_;    
+}
+
+void TMP102::error()
+{
+    while(1) {  // if error, hang while flashing error message
+        led_->write(0);
+        wait(0.2);
+        led_->write(1);
+        wait(0.2);
+    }
+}
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