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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:

Microwire compared to SPI and I2C

Microwire is a three-wire serial interface used by National Semiconductor in its COPS processor family. The three signals are SI (serial input), SO (serial output), and SK (serial clock). SI and SO are input to and output from the processor, respectively. The processor clocks data to the peripheral on SO and receives data on SI. Data in both directions is captured on the rising clock edge. Peripheral devices that transfer data in only one direction (such as display drivers that are only written, never read) may implement only one data line, SO, or SI. Microwire is an older protocol than SPI, and it has some differences from it. Original Microwire has fixed clock polarity and clock phase. At the same time, SPI can be configured to any clock polarity and phase. Unlike I2C, the Microwire protocol has no device addressing built into the serial bitstream. Microwire peripherals require a separate chip select input, one per device. This allows data to be transferred more quickly since address information is not needed. However, it requires more port bits since one chip select, using one port bit, is needed per peripheral. Each Microwire peripheral has a unique protocol based on the application. The…

AVR reads button state and indicates on LED

This is a simple demo program of reading button state, lighting LEDs, sending information via USART. 8 buttons are connected to Atmega16 port A, 8 LEDs to port B via current limiting resistors. While none of the buttons aren’t pressed, there is a running light on LEDs performed, but when any of the buttons are pressed, LEDs display the current 8 bit counter value in binary format. The same value is sent via USART – you can see a number in the terminal is connected. The program is very simple:

Measuring of electrical energy consumption

Electromechanical energy counters were popular for more than 50 years. Today, you can find them only in older houses or in low-budget appliances because today, electronic energy counters are taking their place. And there are many reasons to do so. For instance, measurement accuracy, flexibility, multi-rate support, memory, statistics, remote reading and control, automatic register, and so on. These features can be built into one small chip, which will serve with high reliability and low price. Let’s see how energy (active power) consumption is measured. Active power which is required in the form of alternate current (AC) can be calculated as average power over one period:

DIY USB to RS232 adapter

Sometimes you need to connect some device to a COM port, but the computer doesn’t have one, especially a laptop. There are two ways – go and buy a USB to COM adapter or build one. So if you decided to build a USB to COM(RS232) adapter, there is one solution. This adapter is straightforward to build as there is a single-chip USB to UART bridge (CP2102). This chip from Silicon Labs supports USB2.0 full speed. Internal Resistors are required for the USB interface, integrated clock, internal 1024 -byte EEPROM for Vendor ID, Product ID serial number, power descriptor, and other information. SP2102 USART part support almost all standard features of RS232 communication including handshaking, Databits (5, 6, 7, and 8); 1 or 2 stop bits; odd, even, mark, space, and no parities; baud rate from 300bps to 1Mbits.

Facts about melanoma you should know

Oscilloscope probes for accurate signal measurements

Oscilloscope Probes Measuring signals with oscilloscopes may be a challenging task especially high-frequency ones. Without proper oscilloscope probes, correct measurement of high-speed time-domain signals wouldn’t be possible. For high-speed measurement, you should consider signal parameters like amplitude, source impedance, rise time and bandwidth. There is a wide variety of probes available – passive, active, current-measurement, optical, high voltage, and differential. But let’s narrow the discussion to probes used to measure signals with wide bandwidth and short rise times. There are also many variations on what probe is proper. As probes are potential load to measured circuits, it is important to know their sensitivity to resistive, capacitive, or inductive loading. Incorrectly chosen probes (like high capacitance) can distort the fast-rising signal. Some circuits may not tolerate probes at all (high-speed amplifiers).