Do It Easy With ScienceProg

Building simple power supply from theory to working example

A power supply is an essential part of every electronic device. The whole system relies on it. If a power supply fails – the device dies too, and there is a chance that sensitive parts may be damaged. Power supply solutions vary from device to device. They may work using different techniques depending on needs. Tim has described probably the simplest power supply solution, which converts Alternating Current (AC) to Direct Current (DC). The supply circuit consists of well-known parts – transformer, which transforms voltage from 230V AC to 12VAC, follows diode bridge rectifier, smoothing using large caps and regulation with standard 7805 voltage regulator. Such a solution proved itself in many designs. It is simple, cheap, and builds fast. Tim put everything in the short and informative post without overhead information. Following it, you will be able to construct a 5V DC power supply in an hour.

Updating STM32 C template with CMSIS V3

So far, we’ve been using an old template with CMSIS version 1.30. Since then, it was updated several times by adding new Cortex processor families, fixing several bugs, and adding new features. They also changed the folder structure of CMSIS to be more generic. And there is a CMSIS DSP library integrated. With it, you can do complex math tasks using only a few lines of code. So why not upgrading our software template for Sourcery Codebench G++ toolchain with new CMSIS. First of all, download the latest CMSIS package from arm.com/cmsis. You will have to register to access download files—package with CMSIS, DSP library, and documentation weights about 45MB. Since we are working with ST32 microcontrollers, you also need to download STM32F10x Standard Peripheral Library from STMicroelectronics.

Using SVN for embedded projects. Part 1.

Writing software is a complex task. In every microcontroller program, you usually try to reuse previously registered libraries, downloaded code, and other data that is being updated. What if you are developing something in the team? How do you keep track of everything? Storing project files in directories eventually gets messy – finally, you lose track of what’s done. For instance, sometimes, you have written an LCD library and used it in several microcontroller projects. But eventually, you found a bug or optimized code. Usually, you would have to copy new library files in every project to keep updated. This is hard when you already have dozens of projects. There is one way to stay organized by using version control software. In this case, we will talk about SVN. Subversion (SVN) is an open-source system that allows controlling files and folders, keep track of changes made during the time. Simply speaking, SVN is a virtual file system that keeps track of every change in files, and directories. It’s a clever way of storing project files whether you are working alone or in a team. Using this system-wise, you will always have things organized and never lose the version of your…

AVR DDS3 first tests

Soldering is finished next step is to run fast tests on the AVR DDS signal generator to make sure everything works as expected. It appears that rush design has its consequences, but with few tweaks, it works. First of all, errors found on board.:

AVR DDS3 boards have arrived

Finally, some updates on the AVR DDS3 signal generator. The circuit is practically done, and PCBs are made. I decided to go with two microcontrollers on board to make it more functional. One microcontroller, Atmega328P, is gonna be dedicated to user interface and signal generator control. The second Atmega88 is gonna be used for signal generators only. This will give un-interruptable signal output while changing parameters or simply doing signal sweeps.

12V solar charger using LM317

[Alex] decided to build a solar charger for his car battery. He had an 18V solar panel able to provide up to 83mA. You cannot connect the panel directly to the battery because charging voltage cannot exceed the allowed safe limit, and also solar panels may become a load for the battery in a dark time, and this way discharge it. So he ended up with a simple circuit utilizing LM317 and a couple of resistors setting voltage so that battery would be charged at the recommended 13.2V. To prevent back supply, a Schottky was used. Of course, it adds some voltage drop (0.7V worst case). This was taken into account while calculating voltage adjusts resistor divider. As a test [Alex] left a solar charger for three days connected to his battery, and it charged up to 12.35V which is about 75% of capacity. Not bad at all.

Downloading binaries using STM32 ST-Link Utility

As you may know, ST also produces its own debugger/programmer called ST-Link. It supports JTAG and SWD interfaces. You can purchase an ST-Link USB adapter, but there is a better option if you are into STM32 microcontrollers and probably own one of the ST32 Discovery boards. Since I have STM32VLDiscovery nearby, this is how to program another STM32F103RBT6 board using only four wires. On the discovery board, locate CN3 jumpers and disconnect them as they connect the discovery board to a debugger.

Flashing STM32 using J-Flash ARM

Last time, we covered the topic of flashing STM32 microcontrollers using the bootloader, which is the most comfortable and cheapest way of loading programs into MCU memory. But this isn’t the only way of doing this. The firmware can also be downloaded using the JTAG adapter, which is also used for debugging. This time we are not digging into debugging but staying only with programming. J-Link software You can download the latest J-Link software from the Segger Download page. You will be asked for an adapter serial number which can be found on the backside of the J-Link adapter.

Microcontroller based apps for android mobile phones

Smartphone devices are as valuable as there are some useful apps there. So I started wondering if there are electronics/microcontroller-related apps that could be useful in daily work. Let’s see what we can find in an 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. Let’s see what they are capable of.

Adding self power down functionality to your devices

The power-down feature is convenient on battery-operated devices. For instance, most of the multimeters already have this feature allowing them to self turn off when there is no activity for some time. Check out this simple solution, which uses a pair of FETs and resistors. It was initially made for the Atmega328 project because the author didn’t want to bother with AVR power-down modes. Instead, he used this simple circuit. It can be used to turn the device on with the switch. This is where the P-FET part plays a role and turn off with N-FET. Turn Off signal wire comes from AVR pin market as 5. While the device is powered, N-FET has to be on with a high gate signal. When the N-FET gate signal goes low device turns itself off. This can be used on any device where possible to get such signal conditions. Or use in microcontroller circuit by adding some delay count after inactivity.