Friday, April 12, 2013
Temperature Meter
The
use of temperature devices in temperature measurement and sensing have
made tremendous progress in the last few decades. There are a few types
of measurement solutions that you can implement in your projects. The
use of thermistors or thermocouples are the two most widely used devices
in measurement solutions. The recent decade has seen the use of
integrated circuits devices in many temperature control related systems
because they are much smaller, provide a more accurate measurement and
simpler to be integrated to other digital control devices.
use of temperature devices in temperature measurement and sensing have
made tremendous progress in the last few decades. There are a few types
of measurement solutions that you can implement in your projects. The
use of thermistors or thermocouples are the two most widely used devices
in measurement solutions. The recent decade has seen the use of
integrated circuits devices in many temperature control related systems
because they are much smaller, provide a more accurate measurement and
simpler to be integrated to other digital control devices.
Most
of the digital temperature sensor system has a built-in communication
bus to enable it to communicate with the master control IC. The most
used communication interface is called I2C, a simple bi-directional
2-wire bus that was developed by Philips Semiconductors in the 1980s.
Since then, many devices has this built in communication protocol that
enables all devices that have this feature to be linked together without
any other additional components. The I2C interfacing standard has
become a world standard that are used in more than 1,000 integrated
circuits.
of the digital temperature sensor system has a built-in communication
bus to enable it to communicate with the master control IC. The most
used communication interface is called I2C, a simple bi-directional
2-wire bus that was developed by Philips Semiconductors in the 1980s.
Since then, many devices has this built in communication protocol that
enables all devices that have this feature to be linked together without
any other additional components. The I2C interfacing standard has
become a world standard that are used in more than 1,000 integrated
circuits.
The
I2C standard basically define the start, stop, device selection
addressing and data transfer interfacing protocol. The hardware consists
of 2 I/O lines called SDA and SCL lines.
I2C standard basically define the start, stop, device selection
addressing and data transfer interfacing protocol. The hardware consists
of 2 I/O lines called SDA and SCL lines.
START Condition
The
Start Data Transfer is initiated when there is a change of state of SDA
line from HIGH logic to LOW logic while the SCL line is at HIGH logic.
This is the START condition.
Start Data Transfer is initiated when there is a change of state of SDA
line from HIGH logic to LOW logic while the SCL line is at HIGH logic.
This is the START condition.
STOP Condition
The
Stop Data Transfer is initiated when there is a change of state of SDA
line from LOW logic to HIGH logic while the SCLline is at HIGH logic.
This is the STOP condition.
Stop Data Transfer is initiated when there is a change of state of SDA
line from LOW logic to HIGH logic while the SCLline is at HIGH logic.
This is the STOP condition.
DATA Transfer Condition
The
data transfer is done between the START and STOP conditions with the
data being transferred when SCL transition fromLOW to HIGH logic. Data
is read when SCL is at HIGH logic. SDA line data will only change when
SCL line is at LOW logic.There is no limit to the number of data bytes
transferred and is determined by the master device. Acknowledgement of
successful transfer of data is done between the master and the slave
devices at regular interval.
data transfer is done between the START and STOP conditions with the
data being transferred when SCL transition fromLOW to HIGH logic. Data
is read when SCL is at HIGH logic. SDA line data will only change when
SCL line is at LOW logic.There is no limit to the number of data bytes
transferred and is determined by the master device. Acknowledgement of
successful transfer of data is done between the master and the slave
devices at regular interval.
Digital Temperature Sensor Applications
If
you are into designing of thermostat controls for various buildings,
industrial controls or home appliances, you maywant to consider using
the TMP100 digital temperature sensor from Texas Instruments. This
device can be connected tothe microcontroller using the SCL and SDA
lines.
you are into designing of thermostat controls for various buildings,
industrial controls or home appliances, you maywant to consider using
the TMP100 digital temperature sensor from Texas Instruments. This
device can be connected tothe microcontroller using the SCL and SDA
lines.
The features of the TMP100 sensor include:
* Low Quiescent standby current of 0.1uA means if you choose a proper
microcontroller, the device using battery powered could last for years
compared to the use of thermistor.
* Temperature range from -55 °C to 125 °C.
* Wide Power supply range from 2.7V to 5.5V.
* Accuracy of +/- 2.0 °C.
* Resolution up to 0.0625 ° C.
The typical application of the TMP100 digital temperature sensor is as shown in the diagram below.
