ADT7320_SPI.cpp

00001 #include "ADT7320_SPI.h"
00002 
00003 //#include "mbed.h"
00004 
00005 ADT7320_SPI::ADT7320_SPI(PinName mosi, PinName miso, PinName sclk, PinName cs) : spi_(mosi, miso, sclk),cs_(cs) {
00006     // Chip must be deselected
00007     cs_ = 1;
00008     // Setup the spi for 8 bit data, high steady state clock,
00009     // second edge capture, with a 1MHz clock rate
00010     spi_.format(8,3);
00011     spi_.frequency(1000000);
00012 }
00013 
00014 //Read from register from the ADT7320:
00015 unsigned int ADT7320_SPI::readRegister(uint8_t thisRegister, int bytesToRead ) {
00016   uint8_t inByte = 0;          // incoming byte from the SPI
00017   unsigned int result = 0;  // result to return
00018   // take the chip select low to select the device:
00019   cs_=0;
00020   // send the device the register you want to read:
00021   spi_.write(thisRegister);
00022   // send a value of 0 to read the first byte returned:
00023   result = spi_.write(0xFF);
00024   // decrement the number of bytes left to read:
00025   bytesToRead--;
00026   // if you still have another byte to read:
00027   if (bytesToRead > 0) {
00028     // shift the first byte left, then get the second byte:
00029     result = result << 8;
00030     inByte = spi_.write(0xFF);
00031     // combine the byte you just got with the previous one:
00032     result = result | inByte;
00033     // decrement the number of bytes left to read:
00034     bytesToRead--;
00035   }
00036   // take the chip select high to de-select:
00037   cs_=1;
00038   // return the result:
00039   return(result);
00040 }
00041 
00042 float ADT7320_SPI::readTemp(void)
00043 {
00044     //Read the temperature data
00045     unsigned int tempData = readRegister(0x50, 2); // 0x50 is read commad for 0x02 register
00046     tempData = tempData/8;// MSB bit15 and LSB bit4 so received value need to be divide/8
00047 
00048     // convert the temperature to celsius and display it:
00049     float realTemp = (float)tempData * 0.0625;
00050     return realTemp;  
00051 }
00052