An app note from Atmel, digital sound recorder with AVR and DataFlash (PDF!):
This application note describes how to record, store and play back sound using any AVR microcontroller with A/D converter, the AT45DB161B DataFlash memory and a few extra components.
This application note shows in detail the usage of the A/D Converter for sound recording, the Serial Peripheral Interface – SPI – for accessing the external DataFlash memory and the Pulse Width Modulation – PWM – for playback. Typical applications that would require one or more of these blocks are temperature loggers, telephone answering machines, or digital voice recorders.
Digital sound recorder with AVR and DataFlash - [Link]
The LTC2645 is a family of quad 12-, 10-, and 8-bit PWM-to-voltage output DACs with an integrated high accuracy, low drift, 10ppm/°C reference in a 16-lead MSOP package. It has rail-to-rail output buffers and is guaranteed monotonic. The LTC2645 measures the period and pulse width of the PWM input signals and updates the voltage output DACs after each corresponding PWM input rising edge. The DAC outputs update and settle to 12-bit accuracy within 8μs typically and are capable of sourcing and sinking up to 5mA (3V) or 10mA (5V), eliminating voltage ripple and replacing slow analog filters and buffer amplifiers.
LTC2645 – Quad 12-/10-/8-Bit PWM to VOUT DACs - [Link]
In this Tech Lab, we look at the evaluation board for Micrel’s MIC45212, the 14 amp variant from their line of integrated medium voltage DC-to-DC power modules.
The MIC45 205, 208, and 212 modules integrate the inductor, PWM controller, power MOSFETs, and passives into the package. This integration reduces the total application size, simplifies the design and PCB layout, and improves reliability.
By integrating the passives, Micrel is able to effectively reduce the AC loop size when compared to a traditional regulator with passives routed on the PCB.
Tech Lab – Micrel MIC45212 Evaluation Board for Medium Voltage DC to DC Power Modules - [Link]
by deba168 @ instructables.com:
One year ago, I began building my own solar system to provide power for my village house.Initially I made a LM317 based charge controller and an Energy meter for monitoring the system.Finally I made PWM charge controller.In April-2014 I posted my PWM solar charge controller designs on the web,it became very popular. Lots of people all over the world have built their own. So many students have made it for their college project by taking help from me.I got several mails every day from people with questions regarding hardware and software modification for different rated solar panel and battery. A very large percentage of the emails are regarding the modification of charge controller for a 12Volt solar system.
Arduino solar charge controller and energy monitor - [Link]
by Steven Keeping @ digikey.com
Switching DC-to-DC voltage converters (“regulators”) comprise two elements: A controller and a power stage. The power stage incorporates the switching elements and converts the input voltage to the desired output. The controller supervises the switching operation to regulate the output voltage. The two are linked by a feedback loop that compares the actual output voltage with the desired output to derive the error voltage.
The controller is key to the stability and precision of the power supply, and virtually every design uses a pulse-width modulation (PWM) technique for regulation. There are two main methods of generating the PWM signal: Voltage-mode control and current-mode control. Voltage-mode control came first, but its disadvantages––such as slow response to load variations and loop gain that varied with input voltage––encouraged engineers to develop the alternative current-based method.
Today, engineers can select from a wide range of power modules using either control technique. These products incorporate technology to overcome the major deficiencies of the previous generation.
This article describes voltage- and current-mode control technique for PWM-signal generation in switching-voltage regulators and explains where each application is best suited.
Voltage- and Current-Mode Control for PWM Signal Generation in DC-to-DC Switching Regulators - [Link]
IP phones require data and power on the same cable. A high voltage power source of 48V is required, to reduce the voltage drop in the cable. This project has a DC-DC step-up converter that can deliver the required 48V supply at high efficiency. The MAX668 is an excellent choice for the design of this DC-DC step-up converter. The MAX668, a current-mode controller, operates in the PWM mode at medium and heavy loads, providing high-efficiency and low-noise. With power levels greater than 20W, efficiencies of more than 90% are achievable.
MAX668 48V IP Phone Power Supply – [Link]
Kerry D. Wong writes:
I just got myself a couple of Arduino Due boards. While they were released almost two years ago, I have not really got a chance to look at these until quite recently. Arduino Due is based on Atmel’s ATSAM3x8E 32-bit ARM Cortext-M3 processor. The processor core runs at 84 MHz, which is significantly faster than its 8-bit AVR counterpart ATmega328p which runs at 16 MHz. For an ATmega328p, the highest achievable PWM frequency is 8Mhz (square wave), so we should be able to generate much higher frequency signals on an Arduino Due. But how high can we go? Let’s find out.
On Arduino due PWM frequency - [Link]
Meter clock: keeping “current” time. Read more about the clock:
I’ve seen a few meter clocks in my travels of the web, and I love the idea. A few days ago, I decided that I must have one of my own. Such began the “How to do it” pondering cycle. I had seen builds where the face plate of the meter is replaced. This works, but I wanted to try and find a way to do it without modifying the meter, if possible. After some more ponderation, I came up with what I think is a serviceable idea.
I came across this style of milliamp meter on Amazon. They’re not quite 0-60 mA, but the 0-100 mA (a 0-20mA meter for the hours) is close enough. And they were cheap. So yay.
Part of my requirements were that the clock run off of an Arduino Pro Mini I had lying around, and with minimal additional parts. In order to drive the meters with some degree of precision, I would use the PWM pins to vary the effective voltage across a resistor in series with the meter. This would, by the grace of Ohm’s Law, induce a current that, based on the PWM duty cycle, would be scaled in such a way as to move the needle on the meter to the corresponding hour, minute, or second.
One minor issue came up in the form of the max current the GPIO pins on the ATMega328 chip can source/sink. The pins can source/sink a maximum of 40mA, a bit far from the 60mA needed for the minutes and seconds meters. Enter the transistor.
Using a simple NPN transistor switch circuit, I was able to provide the current for the minute and second meters from the 5V supply. The PWM signals switch the respective transistors on and off, effectively varying the voltage across the resistors in series with the meters.
The resistor between 5V and the meter is actually 2 1/4 watt 100 Ohm resistors in parallel for an effective resistance of 50 Ohms. The two in parallel was necessary as 5V x 0.06A = 0.3W (more than 0.25 that a single 1/4W resistor can handle safely).
Meter clock: keeping “current” time - [Link]
Embedded modules may surprise you by their contribution and an overall costs savings.
As we know „embedded module“ is a quite wide term and it can represent a powerful microcomputer with OS, but it can also be a significantly simpler module with a microcontroller and peripherals, still able to add considerable functionality to a target device.
Typical representatives of useful modules, which add a lot – without big costs are so called quick start modules from company Embedded Artists. Their contribution is in a ready-made „tuned up“ PCB containing for example in case of module LPC4088 QuickStart Board (EA-QSB-016) the microcontroller itself (Cortex- M4), memory, display controller and many interfaces like Ethernet, USB, UART, SPI, CAN, PWM, Analog In/Out, I2C, XBee compatible connector and other.
Especially at low and mid-volume production batches their contribution is mainly in the fact, that it is a really proven solution with a guaranteed operating temperatures range, proper ESD protection and mainly – supported by a wide scale of development tools (free). In case of solving of problems, it´s still possible to contact customer support of company and a lot of hints for successful usage, source codes and libraries can be found directly on the producer´s website.
Try to go easier way - [Link]
Microsoft have released a non-commercial version of Windows based on Windows 8.1 to run on the Intel Galileo development board. A spokesperson for Microsoft said “This preview Windows image is another opportunity for makers and developers to create, generate new ideas and provide feedback to help Microsoft continue making Windows even better on this class of device”.
The board and OS are part of the Windows Developer Program for the IoT (Internet of Things) which Microsoft hopes will encourage developers of Internet-connected devices to experiment with Windows platforms. The Galileo kits include the standard Arduino Wiring API and a subset of the Win32 API. At the moment Linux is the OS of choice among makers and for the next generation of devices but Microsoft hopes to break that dominance. Intel released an update to the original Galileo Gen 1 board earlier this month which features an improved control of its PWM (Pulse Width Modulated) output signals to make the board better suited for the management of 3D printers and robotic applications. Galileo Gen 2 can also be powered from the Ethernet port which the earlier Gen 1 version did not allow.
Galileo now runs Windows - [Link]