You want to measure a temperature using a digital temperature sensor.
The TMP102 sensor is a common digital temperature sensor that uses a standard I2C-based serial protocol.
Wire the TMP102, as shown.
There are two I2C buses brought out to the headers. <<sensors_cape_headers_i2c>> shows that you have wired your device to I2C bus 2, but watch out: the buses aren't always numbered the same. When you work with BoneScript, they are numbered 1 and 2, but if you work from the Linux command line, they are numbered 0 and 1. Confusing, huh?
Once the I2C device is wired up, you can use a couple handy I2C tools to test the device. Because these are Linux command-line tools, you have to use 1 as the bus number. i2cdetect, shown below, shows which I2C devices are on the bus. The -r flag indicates which bus to use. Our TMP102 is appearing at address 0x49. You can use the i2cget command to read the value. It returns the temperature in hexidecimal and degrees C. In this example, 0x18 = 24C, which is 75.2F. (Hmmm, the office is a bit warm today.) Try warming up the TMP102 with your finger and running i2cget again.
bone# i2cdetect -y -r 1
0 1 2 3 4 5 6 7 8 9 a b c d e f
00: -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- 49 -- -- -- -- -- --
50: -- -- -- -- UU UU UU UU -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --
bone# i2cget -y 1 0x49
0x18