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Simple signal drawing on graphical LCD routines

During my spare time, I have been playing with graphical LCD. This time I decided to display simple signals that are stored in microcontroller memory. The idea was to read signal values from a lookup table and display waveform on Graphical LCD. To make things more interesting, I divided the LCD screen into four smaller screens to activate them separately and draw signals in them. Graphical LCD is the same old HQM1286404 with KS0108 controller. I have used Proteus simulator 128×64 graphical LCD(LGM12641BS1R), which is based on KS0108. How to implement and connect LCD there was a blog post (Simulate KS0108 graphical LCD with Proteus simulator )about it. I am just going to show main program routine. As I mentioned I have split 128×64 in to four smaller screens like this: So I get four smaller 32×63 screens where I can put different information. To do this, you can think of many ways of implementation. I have chosen a simple solution. I have created a simple structure that holds a currently active window position and size:

How does RFID tag technology works

RFID introduction RFID tagging technology is successfully used among us. Still, we don’t notice them always and do not think about them as they are not noticeable because we do not have to take any actions to transfer or read any information from RFID tags. But probably everyone notices in big supermarkets, book stores two parallel frame antennas and thicker labels on products you buy, or maybe you have an RFID entrance card at your work. So let’s see how this technology works. RFID is a so-called Radio Frequency Identification system that consists of two main parts: transmitter and receiver. The labels, access cards, and even passports in some countries have RFID transponders integrated. These transponders are called tags. Each tag has information programmed in it. A reader can read this information via the Radio Frequency link. Tags can be very miniature, like thicker paper sheets. The simplest ones have only an antenna and diode. These tags only reflect signals incoming from transmitters. These are tags that are used in supermarkets and other places for securing goods from stealing. If the signal is reflected, an alarm is triggered. When the seller scans the tag, it is electrically destroyed to trigger…

Interfacing microcontrollers to external devices

There can be any external device that may be connected(interfaced) to the microcontroller. They may be for control input like buttons, keypads, touch, or information output, e.g., display, sound, motor, relay, and modem. Also, output devices may be further chips like transmitters, frequency generators, memory. Interfacing with chips is not that hard because most of all (especially digital ones) are TTL level compliant that allows connecting chips one to another directly. Otherwise, there are TTL level converter chips if needed â€“ like RS232 to TTL converter MAX232 chip. Let’s take a simple device LED. Probably many of you are thinking that there is nothing easier than connecting LED to the microcontroller. Yes, it’s true. Considering AVR microcontrollers, Led can be connected directly to port pin via limiting resistor either as a source either as drain because the chip can provide enough current to light diode without damaging the port. But what if you need to connect like 10 LEDs when each requires, let’s say 20mA. The total current would be 200mA. No tall microcontrollers can provide such power directly without damaging the port. The simplest way to avoid this problem is to use LED via amplifying transistor.

DIY pulse soldering iron

The biggest benefit I see when working with a pulse soldering iron is speed and effectiveness. Of course, when you don’t work, it stays cool; this means it saves energy, doesn’t evaporate poisonous steam, and there is no risk of accidentally burning yourself. Well, this one even has a light source for a better view when soldering. If you like to hack things, you may try this challenge on building a pulse soldering iron. This iron may be powered from a 220V supply and consumes about 70-100W of power. Efficiency reaches about 50%. The heating time takes 5 seconds while cooling to 50ºC takes about 15 seconds. Soldering iron may be used in various tasks, including repairing home appliances, replacing electronic parts, etc.

Kick start guide to start working with Programmable Logic Devices from Altera

Probably everyone knows what logical IC’s and how to use them in the design are. But if the design is more complex, electronics enthusiasts are more likely to choose microcontrollers as they minimize the count of external components. But the problem is that not everything is possible with microcontrollers. They have many disadvantages when a fast response to input signals is needed. Microcontrollers execute operations one by one in sequence (conveyor). So output results will occur after some number of clock cycles. One way is to use hard logic IC’s. But when complexity grows – the number of IC packages also increases. This way design board becomes tremendous. So where programmable logic devices (PLD) comes to help. CPLD devices have many base elements (gates) without strict electrical interconnection. So designer can program these connections to combine any logical combination. Programmable logical devices allow the construction of any logical device, including counters, triggers, etc. The limit is only the number of base elements and connection lines. So it is better to start with learning tools that allow the construction of logical circuits, simplify them, and avoid many mistakes. One of them is MAX+plus II BASELINE and CPLD from ALTERA. This software…

DIY simple band-pass filter

This filter was designed to filter the 1kHz frequency of the telemetric signal from environmental noise. The filter itself is straightforwardly built with acceptable electronic parts worldwide. This filter can be used in any circuit because of its simplicity. The circuit contains a minimal amount of parts, including one general-purpose NPN transistor with coefficient 50…70 and more. Such filter blocks may be connected in series directly one to another(second IN first OUT). This way, filter gain may increase up to 1,2…2.

Testing AVR universal bootloader on Atmega128

After the project source code is developed, there is always a need to flash it to the microcontroller. There are a few ways to program AVR microcontrollers. Usually, we used to flash AVR’s with an ISP adapter (or another programmer) that is not always handy, especially when designing a device for the end-user who doesn’t have an ISP adapter or doesn’t know much about flashing MCU. So it is better to flash a bootloader program AVR MCU once with a programming adapter and later load firmware interactively when starting AVR. The bootloader allows updating the firmware without a programmer and enables different programs for different purposes depending on the situation flexibly. But enough about this. So my purpose today is to test AVR universal bootloader, which Shaoziyang is developing. He aimed to create a universal bootloader that works on different AVR microcontrollers with minimal code modifications. Bootloaders you can find on the Internet are mostly available for particular microcontrollers, and nobody wants to do a lot of modifications to adapt to different MCU when needed. This AVR universal bootloader can support most AVR microcontrollers (Mega series), which have the self-programmable capability, boot section, and UART. If the device has many…

Easy way to measure motor torque

Motor torque (momentum) is one of the motor ratings used to indicate the rotary motor force produced on its output shaft. The motor torque rating is usually captured at the point when the motor is stalled. The torque measurement unit is (Nm) in the metric system or (ft-lbs) in the US system. But the principle is the same torque is a multiplication of lever length (r) and force(F) applied to lever: I=r x F So there is a simple experiment on how to measure motor torque quite accurately without any fancy measuring tools. All you need is a motor of which torque will be measured, a nominal power supply of motor, thread long enough, a mass of known weight, ruler, and a table or other lifted surface where the motor will be fixed.

Testing pulse transformer with an oscilloscope

Pulse transformers are a little different from regular AC transformers. In AC transformers, magnetic flux alternates between negative and positive values in the core, while in pulse transformers, magnetic flux is unipolar. Pulse transformers are used in TV, computer power supplies. If you need to test a pulse transformer, it may be almost impossible to do this with an ohmmeter, even a digital one, because the windings of impulse transformers have meager active resistance except for high voltage ones. One way to test is to measure the inductance of windings and compare them to values in specifications. Still, not everyone has the ability to measure inductance, and not always you have transformed specifications near by. So there is another way to test pulse transformers, which may be acceptable to almost everyone radio-hobbyist, using a low-frequency generator that works at the resonance frequency of contour, which consists of external capacitor and pulse transformer winding.

How to describe embedded software design using diagrams and pseudo-code

When designing embedded hardware, you probably want to visually express what embedded software will be performing and how different functions depend on each other. How to make software documentation simple, clear, and informative. If you are a developer, you may want to explain your ideas understandably without loads of code text. Depending on what level of information has to be provided, you may choose any of the following. Data Flow Diagram Data flow diagrams are used to see the processes and what data is transferred between different functions. This way, each process or function is expressed as a block (or any other shape), while lines show what information passes between processes. As you can see in the example figure simple data flow diagram is presented. Without program code, it is easy to read how the program operates: