Do You Really Know What LIN is?

LIN stands for Local Interconnect Network.  Yes, from those words, we can say that it's a local network. But do we really know how it works? A LIN consists of LIN Master and a LIN Slave. Data is exchanged and encapsulated in data frames with a fixed structure. These data frames always contain a break field that indicates a new incoming frame.

Here’s a video that explain what LIN is:

Here are the advantages of using LIN

• Easy to Use
• Components available
• Cheaper than CAN and other communications buses
• Harness reduction
• More reliable vehicles
• Extension easy to implement
• No protocol license fee required

Although LIN is now a full replacement to the CAN bus, it will always be a good alternative whenever low costs are essential while speed/bandwidth is not important.

• Below are the applications where LIN can be used:
• Roof – Sensor, light sensor, light control, sun roof
• Steering Wheel – Cruise control, wiper, turning light, climate control, radio
• Seat – Seat position motors, occupant sensors, control panel
• Engine – Sensors, small motors
• Grille – Grille shutter
• Climate – Small motors, control panel
• Door – Mirror, central ECU, mirror switch, window lift, seat control switch, door lock

Wireless Sensing Network for My Next Project

In this project, we will be creating an incredible Wireless Sensing Network. This project uses the TH71221 RF, which we will use in the RF transceivers. The source of this project also discusses how the TH71221 RF is being used with other external components in building the WSN node like that of the microcontroller and sensors.

So what’s a Wireless Sensing Network? It is a network consisting of spatially distributed autonomous modules (called nodes) using sensors to monitor physical or environmental conditions such as temperature, pressure and humidity. It’s a good compliment to the previous project we have about InfraRed thermometer. The devices we will be using will communicate wirelessly to a main sensor node which collects back all the measurements and sent it to a main station, like a computer, for further processing.

This is where the device can be applicable:

• Wireless sensing networks for temperature, humidity, light and RF field strength
• Home and building automation

Even around with several components, the TH71221 RF transceiver used in this project can be used in a low cost wireless sensing network applications. While Melex TH71221 is used to transmit as well as receive information over a wide frequency range of 300 to 390 MHz, the external microcontroller handles the network protocol of this communication.

Tired of Using Conventional Thermometer? How about Using the InfraRed Thermometer?

Yes, conventional thermometer is a pain in the arse. In the age of innovation, contact measurement is the thing of the past. Machines and gadgets of today uses high technology in measuring heat, pressure, distance, speed, etc. They use lasers or infrared to the non-contact measurements. We all notice this on the streets, where cops uses speed measuring device that uses infrared.

So what could be a good project that to created a device that can measure temperature that has that capability for a non-contact measurement? I found this article featuring this new sensor that uses infrared to gather data. The sensor is called MLX90614 produce by the company Melexis Microelectronic Integrated Systems.

Digital, plug and play, the MLX90614 is an infrared thermometer that’s small in size and has a low cost. With high accuracy features and medical accuracy benefits, the component is easy to migrate. Whilst it is factory calibrated, it also offers different package options for different applications.

Low noise amplifier, 17-bit ADC and a powerful DSP unit are integrated into the MLX90614 to achieve high accuracy and resolution of the thermometer. A digital SMBus output is included to the component giving full access to the measured temperature in the complete temperature range with a resolution of 0.02°C. Comes with both IR sensitive thermophile detector chip and the signal condition in ASIC integrated in the same TO-39 can, the MLX90614 allows the user to configure the digital output to be PWM. With an output of 0.14°C, the 10-bit PWM is configured to continuously transmit the measured temperature in range of -20 to 120°C as its standard.

So now we have a high-tech thermometer in our hands.

A Solution to Your Empty Batteries

Empty battery, we all experience it. It’s really annoying to see an empty battery. Much of the devices applications nowadays eat up too much of our battery juice. Although devices have chargers, what I really don’t like about it is that some chargers cannot be used on cars. When you’re on a long journey and use your gadgets to entertain yourself, battery life is a nightmare.

So I wanted to create a universal battery charger that’ low cost, yes you heard it folks, at a very affordable cost. This universal charger is for NiCD – NiMH batteries. This circuit is ideal for car use (just what I needed for). The cool thing about this is it has the ability to transform mains adapter into a charger.  The circuit has an LED to indicate charging. This project can be built on a general PCB or a veroboard.

The full specification of this project is located here.

DIY Uninterruptible Power Supply to the Rescue!

Much of the country’s power source rely on hydro power plants, and does rely on water. These last two months, we’ve experience rotating brownout and it’s kinda messing up everything. Long hours of not having electricity are torture to everyone. It also messes with my work, and gets lots of backlogs. What I really don’t like about brownouts is that it comes like thief, which ruins everything when you’re doing something on your computer (reports, excel files, powerpoint presentations, etc.) and forgot to save it.

I don’t want to experience those nightmares anymore so I searched for an affordable UPS in the market. But buying the device is too mainstream, so why not create my own? I searched the big G for tutorials on how to make your own UPS and found this one.

As you can see on the circuit drawn on this project, the diagram shows how the batteries take control during a outage in electrical power supply.  The input to the primary to the primary winding of the transformer is 240V as stated. If the value is at least 12 Volts running, the secondary winding can be raised for up to 12 Volts.

The circuit in this project was designed to offer more flexible pattern where we can use different regulators and batteries to produce regulated and unregulated voltage if we want it to be customized.

So now I will have no worries if an outage will come. Now that is awesome!

Looking for a Low Cost Frequency Counter Circuit?

So I was looking for a device that can measure the rpm of my car. There are some that I found on electronics hardware, but they’re quite expensive! So I did some research and lots of googling to find some ways and alternatives so I can have a device for my beloved mini copper.

What I wanted for my frequency counter is that, I wanted the device to be able to observe and oscillator’s accuracy, it can measure the mains frequency and can find out the rpm of a motor that is connected to an encoder. It’s typically and all-around frequency counters.

I did a lot of research and found this interesting tut about how to build your own frequency counter circuit. What I love about this DIY frequency counter is that the cost will be low.

The project we will be making is just a basic, low cost frequency counter circuit. The device can measure 16Hz to 100Hz signals with maximum amplitude of 15V.  The device’s sensitivity is high, with resolution of 0.01Hz as stated by the tutorial. The input signal can be a sine, a square or a triangle waveform.

I've also found this document by Wolfgang "Wolf" Büscher, Frequency counter with a PIC and minimum hardware, it's also a good alternative, but on a much higher price for the parts.

So now let’s get started and make our hands dirty.

Wired Communication is not dead, yet.

Yes, that’s right, wired communication is not dead, not today. We all know that wireless is the future of communication and it grows very fast. But we can deny the fact that long distance funicular communication is still popular.

On this project, we will be converting RS232 and RS485 with an Automatic RS – TX control. One of the most used, easy to develop and easy to apply communication protocol, the RS232 is generally the standard at the MCU applications. But the restriction, it only allows us to use maximum 15 meters cable. The main problem with using RS232 is that when the distance increase, the noise at the common ground line also increases. Another issue on using RS232 is that we are only allowed to only two devices to communicate reciprocally.

With the above problem mentioned while using RS232, RS485 is here to the rescue. What the RS484 separates from RS232 is that it can transfer data depending on the potential difference the two communication wires. On RS484, we can transfer data up to 1220 meters far away and with a rate up to 10Mbps and we can have 32 devices that can be joined.

The main advantage of this converter is, it can detect the incoming/outgoing data and switch the TX and RX modes of MAX485. It controls the DE and RE enable bits automatically. The RS485 lines A and B are taken from the screw terminal block. The connections are shown in the layout that is inside the downloadable zip package.

Be a Spy with This Cool DIY Spy Microphone

Have you ever thought of picturing yourself being a spy? Doing covert operations and spying on people? Nah, I think you've only seen them on movies, yes on movies, but how about giving it a try, though not professionally.

So I’ve decided to give it a try. One cool thing that most spies used is a spy microphone. I found this cool spy microphone that uses laser. How cool is that, a spy microphone and a laser is too awesome right?

Though I found about this tutorial as not the most practical recording setup we can every used, but it still in an interesting bit of science and a great DIY Project.

What’s so cool about this thing is that it will allow you to listen inside of buildings hundreds of feet away from you (yes, I know what you’re thinking, lasers are awesome). The process of creating the device involves a simple bit of soldering and all we will need is a laser pointer, tripod and old pair of headphones, photocell and a recording device.

Here’s a simple diagram of the device. Sorry, just grabbed it from the source.

The output forms a complex signal when an electric current passes through the said diaphragm, which can then be interpreted by a recording device as sound. It can record sound though windows with a laser pointer and cheap parts you can find at any electronics store.