Turn-key PCB assembly services in prototype quantities or low-volume to mid-volume production runs

Testing NEO-6M GPS receiver module

If your project requires global positioning feature, then you should use one of many GSP modules. There are many receiver modules and expansion boards available for your choice. They vary in PCB size, functionality, antennas used and price. In most cases, you are probably looking for simple, small all in one solution where GPS receiver and antenna would be on the same package. Recently I have picked one that might fit for most needs – GPS receiver NEO-6M module with ceramic antenna and TTL serial interface. It is a very compact GPS module with most needed features:

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Trying DSO138 digital oscilloscope from Gearbest

We all agree that hobbyist or engineer should have proper bench oscilloscope for everyday use. They have all standard features including built in screen, interchangeable probes and convenient knob controls. Anyway if you are looking for temporary cheap solution, you can try building your own oscilloscope. Luckily you don’t have to make it from scratch because there are many projects and kits available that are cheap but powerful enough to fit most of basic needs.

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Using current limiting resistors on AVR I/O pins

Today I want to talk about protecting digital Inputs of AVR or any other microcontroller from over-voltages. When you look at majority microcontroller circuits found on internet shared by the hobbyists you don’t find any input protection, some argue that in most cases this is not needed, or don’t understand how it works. Let’s see how simple resistor can save the day. Lets see at simplified version of digital input of AVR microcontroller. We can see there that input uses CMOS logic where the transistor is switched by voltage. According to AVR datasheet, the gate control voltage should stay within -0.5V to VCC+0.5V range. If we power our device with a 5V supply, we need to make sure that the pin input voltage stays in the range -0.5 to 5.5V. When the input voltage source is taken from the same power supply, then we don’t have to worry much about it. But what if AVR is accepting digital signals from other sources like sensors, other devices that are powered with their power supplies. Can we be sure that voltage will always be within safe limits? This is why there are two clamping diodes (sometimes called ESD protection diodes) used. They…

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Understanding 1-wire interface

1-wire devices. DS18B20 and iButtons

1-wire devices are commonly used in many applications. You probably are familiar with famous DS18B20 digital temperature sensor in TO92 package. They can be powered and interfaced using same single data line plus ground return of course. 1-wire originally was designed by Dallas Semiconductors Corp. which is also a major provider of 1-wire devices like temperature sensors, timers, real time clocks, memory and well known iButton. 1-wire interface is a bidirectional, half duplex slow serial communication standard. It doesn’t use any clock signal. When talking of speed, standard data rate is 15.4kbps. But there is possible to overdrive 1-wire communication to up to 125kbps.

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Microcontroller based apps for android mobile phones

Recently I obtained a Samsung Galaxy Ace S5830 android mobile phone. It was released a year before but it seems to have enough power to run most of apps you can find around. It is powered by Qualcomm MSM7227 ARM11 processor running at 832MHz. Has internal 158MB of internal memory and can support up to 32GB MicroSD flash card. Other features include GPS, WiFi, 320×480 TFT touch screen, 5MP camera and so on. Device is powered by Android OS v2.3. These are specs you can find on any mobile website. To get your own Samsung phone, check out phones4u. Smart phone devices are as valuable as there are some useful apps there. So I started wandering if there are electronics/microcontroller related apps that could be useful in daily work. Lets see what can we find in app store. First of all we are interested in free apps. Search on AVR microcontrollers gave me coupe results: AVR Fuse Calculator and Using Atmega128 apps. Lets see what are they capable of.

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ECE4760 Spring 2012 projects are here

Some time ago we noticed that Cornel University ECE4760 project list started to build up. It seems that the project list is finished with 30 great projects built around AVR microcontrollers. Students as always prove to be creative and inspiring. Like each year they came up with new ideas and implementations. We like that they use free tools to build them. The compiler they use is WinAVR/GCC compiler. So everyone can replicate one or another idea if needed. It is hard to go through whole project list as it would tike time and we still wouldn’t be able to tell the thing. Some of them really are worth attention like EEG Pong, where device reads brain waves and this controls computer cursor.

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