Finally some update on AVR DDS3 signal generator. 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. Second Atmega88 is gonna be used for signal generator only. This will give un-interruptable signal output while changing parameters or simply doing signal sweeps.
Simple keypad should be convenient for entering frequency values and menu navigation. (more…)
STM32F103R board is a simple and easy development board to learn STM32 microcontroller programming. Its heart is STM32F103RBT6 ARM Cortex-M3 microcontroller with 128K of Flash and 20K of SRAM memory. It can be clocked at maximum 72MHz frequency and is considered to be a medium-density performance line microcontroller. Other features include USB, CAN, 7 timers, 2ADCs and 9 communication interfaces.
Development board has several nice features to get started with. First of all it has RS232 interface for communicating and accessing bootloader. There also is a USB 2.0 full speed interface connector that also can work as power supply. Next is a JTAG connector to program microcontroller using tools like J-Link adapter. Two push buttons and two progammable LEDs are hardwired to MCU pins alongside all I/Os connectors. (more…)
Nearest star from Earth is Sun. And it emits huge amount of energy which is free. No surprise many people try to get most of it with minimal cost. Photovoltaic solar panels still have low efficiency and yet are quite expensive. Everyday we hear how their efficiency is increased by introducing new technologies. Anyway solar panels require direct Sun which in some regions doesn’t appear very often. So how we can get this energy with almost no initial cost? The easiest way to do so is to build a solar thermal collector. You can find lots of high efficient commercial collectors. They look great and at some level works in winter time when Sun shines. I decided to go simpler. I need hot water only in spring, summer and fall. In winter time I burn wood to heat the house an so water. In summer time I usually heated water using electric boiler which generates nice bills at the end of month. No more…
So I started this project which is still in testing phase. But seems to work fine. Lets go through build process how I made a simple solar collector using old window frame. First of all I was lucky I’ve got this old window frame which area is about 1 square meter. (more…)
High density line of STM32 microcontrollers have quite a bunch on features that can be used in user programs. The more features you add to source the more complicated program becomes and this way it starts to be difficult to keep up with all things. Using only main loop and interrupts becomes time consuming task to manage. If you don’t want to struggle in tuning things up manually you can use one of many real time operating systems (RTOS). They are great when you need lots of separate functions to run in parallel so no task would be missed. RTOS scheduler takes care of giving each task a decent time to perform. There are lots of great RTOS systems around. Many of them are free and opensource.
It happens so that I love using FreeRTOS which has quite long history and is flexible enough to fit multiple types of hardware. You can check out my recent demo on Atmega128. I encourage you to give a try to other RTOS systems like ChibiOS, BeRTOS, and many more. But lets stick with FreeRTOS. Simply speaking FreeRTOS is quite simple and easy to use. It has practically most of features you’d look for in RTOS. Some of key features would include preemptive, cooperative and hybrid scheduler, task and co-routine support, queues, semaphores and mutexes for task synchronisation and communication. Many demos, many ports to to get started with. (more…)