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Humidity and temperature measurements with Sensirion’s SHT1x/SHT7x sensors (Part 1)

Posted on May 28, 2011 by R-B 5 comments

Temperature and relative humidity are two very important ambient parameters that are directly related to human comfort. Sometimes, you may be able to bear higher temperatures, if there is a lower relative humidity, such as in hot and dry desert-like environment. However, being in a humid place with not very high temperature may make you feel like melting. This is because if there is high relative humidity, sweat from our body will evaporate less into the air and we feel much hotter than the actual temperature. Humidifiers and dehumidifiers help to keep indoor humidity at a comfortable level. Today we will

Can’t access to Microchip’s website this morning

Posted on May 25, 2011 by R-B 7 comments

When I tried to access microchip.com this morning, the page didn’t show up. This is what I have been seeing. I can’t access to any information and datasheets. Is anybody else having the same issue? Sorry, it was my bad, I have this problem with one of my machines, but it’s working good on other machines. I should have checked this before.

Lab 15: Scrolling text message on an LED dot-matrix display

Posted on May 21, 2011 by R-B 160 comments

In Lab 12, we learned about the basic structure of a monochrome (single color) LED dot matrix and its interface with a microcontroller to display static characters and symbols. Today’s lab is its continuation, and we will be discussing on displaying a scrolling text message on a 16×8 LED dot matrix. The microcontroller used is again the same PIC18F2550 from StartUSB for PIC board. The 16 columns of the LED matrix are driven individually by two shift registers (74HC595), whereas the eight combined rows are driven by the decoded outputs from a decade counter (CD4017). In Lab 12, columns were

Lab 14: Inter-Integrated Circuit (I2C) communication

Posted on May 9, 2011 by R-B 34 comments

I2C (Inter-Integrated Circuit) is a short distance serial interface that requires only 2 bus lines for data transfer. It was invented by Philips in 1980’s, originally to provide easy on-board communications between a CPU and various peripheral chips in a TV set. Today, it is widely used in varieties of embedded systems to connect low speed peripherals (external EEPROMs, digital sensors, LCD drivers, etc) to the main controller. In this experiment, we will cover an overview of I2C protocol, its implementation in PIC microcontrollers, and the method of connecting single and multiple devices on a common I2C bus. We will

Lab 13: Read and Write to internal EEPROM

Posted on May 4, 2011 by R-B 15 comments

EEPROM (Electrically Erasable Programmable Read-Only Memory) is a type of non-volatile memory which can be programmed, erased, and re-programmed electrically while it is on the circuit board. A majority of PIC microcontrollers come with some built-in EEPROM which is a great place to store data that should not be lost when the system is powered down. A good example is a digital lock system where the access code can be stored in the EEPROM of microcontroller so that the contents remain intact even after the power supply has been removed. In my ‘Beginner’s data logger‘ project, I used the internal EEPROM

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