If your project require 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 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 very compact GPS module with most needed features:
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.
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 hobbyists you don’t find any input protection. Some argue that in most cases this is not needed, or simply don’t understand how it works. Lets see how simple resistor can save a day. Lets see at simplified version of digital input of AVR microcontroller. We can see there that input uses CMOS logic where transistor is switched by voltage. According to AVR datasheet, gate control voltage should stay within -0.5V to VCC+0.5V range. If we power our device with 5V supply, we need to make sure that pin input voltage stays in range -0.5 to 5.5V. When input voltage source is taken from 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 own 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 are here to protect logic from …
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.
During time I’ve been purchasing or building various microcontroller boards. Most of them were used just to try things out or because they were cheap to get. So I thought, why not to blow dust away and see what we have here. Maybe there will be some fresh thoughts on where to use them. Probably I should spare a few words about each of them.