Shawon M. Shahryiar @ embedded-lab.com writes:
In embedded systems, oftentimes it is needed to generate analog outputs from a microcontroller. Examples of such include, generating audio tones, voice, music, smooth continuous waveforms, function generators, voltage reference generators, etc. Traditionally in such cases the most common techniques applied are based on Pulse Width Modulation (PWM), resistor networks and external Digital-to-Analog Converter (DAC) chips like MCP4921. The aforementioned techniques have different individual limitations and moreover require external hardware interfacing, adding complexities and extra cost to projects. XMega micros are equipped with 12 bit fast DACs apart from PWM blocks and again it proves itself to be a very versatile family of microcontrollers. In this post we will have a look into this block.
XMega DAC - [Link]
With a focus on the 2.4 GHz RF application area, Holtek is delighted to announce its new I/O Type Full Speed USB Flash MCU, the BC68FB540. This device forms one of a series of new generation 8-bit Flash USB RF MCUs. The 2.4 GHz RF Transceiver includes the features of low power consumption, high performance and high noise immunity characteristics and has a data rate of up to 2 MBPS.
The BC68FB540 is compatible with the USB 2.0 specification and has an operating voltage of 2.2 V to 5.5 V, and with an operating temperature of –40 °C to +85 °C it meets with industrial specifications. The RF circuitry derives its system clock from an externally connected 16 MHz crystal while the MCU system clock is derived from a fully internal 12 MHz HIRC oscillator.
Holtek New BC68FB540 2.4GHz Full Speed USB Flash Type RF TRX MCU - [Link]
Jason Bowling writes:
Over the last year I’ve been working towards an underwater sonar system for ROVs and surface boats. In order to learn the basic signal processing required to detect the echoes, I initially got a simple sonar working in air with a desktop conferencing USB speaker/mic running on Windows. A writeup, including source, is here. That article describes the algorithms used in detail and would be a good read if you want the details of how this works.
The next logical step seemed to be to get it working on a microcontroller. There are plenty of low cost ultrasonic sonar modules available that work really well in air, but the idea was to work towards getting a sonar that worked in water. There are currently no low cost sonar modules for hobby use in water.
Audible Frequency Chirp Sonar with the Stellaris Launchpad - [Link]
Joe @ hobbyelectronics.net:
Here you will find complete construction details including circuit diagrams, PCB layouts and PIC firmware (and the source code). The code was written in Proton PIC BASIC but the good news is that there is now a free version of this compiler available for download; AMICUS18.
PIC Digital Thermometer & Clock - [Link]
by Ashish Kumar and Pushek Madaan @ edn.com:
In our modern era, digital logic has become the core of all the electronics circuits either in the form of an FPGA, microcontroller, microprocessor, or discreet logic. Digital systems use many components that must be interconnected to perform the required functions. The vital element for proper operation of such a digital system is a CLOCK signal that enables all these digital components to communicate and establish synchronization between them. Hence, we always need a source to generate this clock signal.
This source comes in the form of an oscillator. Although most of today’s microcontrollers have an integrated RC oscillator, the clock generated by such an internal RC oscillator is typically not good enough to support the precision required for communication with other modules in the system. Thus, an external oscillator is required that can provide a clock signal to the complete system and yet meet all the requirements for precision, signal integrity and stability.
Oscillators: How to generate a precise clock source - [Link]
ARM PRO MINI is a small barebone open source ARM M0 microcontroller board that is great for quick prototyping and as a starting point for your own ARM based custom designs. It was designed and named after the venerable Arduino Pro Mini and it is an excellent stepping stone for makers and hobbyists ‘graduating’ from Arduino to the ARM architecture.
ARM PRO MINI - [Link]
Ralph Doncaster writes:
Since the release of V-USB, dozens of projects have been made that allow an AVR to communicate over USB. USB data signals are supposed to be in the range of 2.8 to 3.6V, so there are two recommended ways to have an AVR output the correct voltage. One is to supply the AVR with 3.3V power, and the other is to use 5V power but clip the USB data signal using zener diodes. Most implementations of V-USB, like USBasp, use the zener diodes. I’ll explain why using a 3.3V supply should be the preferred method.
USB interfacing for AVR microcontrollers - [Link]
by Nurgak @ github.com:
To measure my electricity usage I decided to build a small system that would count LED blinks on my power meter which indicate the used Wh. It was pretty straight forward system requiring an Internet connected microcontroller to log the data and some sort of sensor that would detect LED blinks on the power meter which is not my property and thus not accessible or modifiable.
The main reason to do this project is to get a better overview of the electricity usage as the house is heated by a heat pump so basically everything works on electricity or other free (thermal solar collector) and renewable sources (stove).
I had a CC3200 development kit laying around, it’s featuring a chip with Wi-Fi and an ARM Cortex-M4 processor running at 80MHz, it was more than enough to fill all the needs of this project.
Electricity usage monitor - [Link]
Bob Alexander of Galactic Studios made this bluetooth serial monitor for embedded microcontroller projects, the Blueprintf:
One way of debugging microcontroller-based projects is to send messages out the UART serial port. Then, a UART-to-USB interface can feed the messages into your PC for display. But I wanted a small, portable device for viewing serial data without a PC, and I wanted it to use my cell phone or tablet for its display.
There are a few advantages to this. First, I don’t always have my PC nearby; maybe the project worked fine on my workbench, but doesn’t work “in the field” where I don’t have a PC handy. Second, the UART-to-USB interface sometimes hangs, especially if there are glitches from the system under test (SUT). Finally, sometimes I just don’t want to string the wires from the embedded system to my PC
Blueprintf – a bluetooth serial monitor - [Link]
AtmelCorporation have announced two additions to their SAM G series of ARMCortex-M4-based MCUs. The two latest models are designated the SAM G54 and SAM G55. They feature high performance (up to 120MHz), low-power (102 µA/MHz in active mode, down to 5 µs wake-up) and tiny outline (as small as 2.84 x 2.84mm). Both are targeted at IoT applications and include all the features of the current SAM G family of devices including an Atmel | SMART ARM Cortex-M4 MCU + FPU (floating point unit) together with integrated sensor fusion algorithms.
Two new MCUs from Atmel - [Link]