USB OTG explained in this app note from Cypress Semiconductors. Link here
This application note discusses several aspects of OTG functionality. The note introduces end-applications and different types of cables and connectors involved with OTG. It also describes the OTG protocol state changes when both Mini-A and Mini-B devices are connected .The host negotiation protocol (HNP) and session request protocol (SRP), which are part of the OTG protocol, are also explained.
The Acorn Master cartridge breakout board by Simon Inns:
This project provides a simple breadboard adapter/breakout board for prototyping cartridges for the Acorn BBC Master and Acorn Electron 8-bit computers.
The design consists of two PCBs, the first plugs into the computer’s cartridge slot and the second is designed to plug along the edge of a standard 2.54mm pitch breadboard. The two boards are connected by a length of 50-way ribbon cable.
Project info at waitingforfriday.com and GitHub repository here.
Dilshan Jayakody published a new build:
This project is about an open source, USB based, 10 digit seven segment display unit. This unit is specifically designed to work with POS systems and banking applications. Initially, this system is developed to work with PC based systems, and later it was modified to work with other platforms and applications.
See the full post on his blog.
AVR ATmega MCP4728 DAC library:
The MCP4728 device is a quad channel, 12bit voltage output DAC. It also has EEPROM embedded. The DAC is driven using the I2C interface.
This library implements an ATmega driver for this IC.
More details on Davide Gironi’s blog.
Check out the video after the break. Continue reading “Use a MCP4728 DAC with AVR ATmega”
Shawon Shahryiar over at Embedded Lab shared a how-to on making a SPL dB meter:
Sound needs a medium for propagation or travel. It can’t travel in vacuum. Normally air is that medium but sound can also propagate in liquids and other states of matter. I am not going to lecture on how sound travels and its properties as Wikipedia details everything well here. Everything we see around us has a measurement and a unit. In case of sound pressure, the unit is decibel. Our basic requirement is to be able to measure Sound Pressure Level (SPL) in decibel scale with a typical 8-bit microcontroller, an ordinary microphone and without involving complex algorithms.
Measurement of sound has a number of uses. For instance, monitoring sound pollution, security system, monitoring the quality of an amplifier, detecting sound profile of an environment, etc.
Hardened circuit protection against voltage spikes and surges tackled in this app note from Vicor. Link here (PDF)
Electrical systems in military vehicles are normally required to meet stringent transient requirements. Typical of these specifications is the MIL-STD-1275B. Although the specified levels of these surges and spikes are outside the capability of Vicors Maxi, Mini, Micro Series modules, it is quite possible, with simple circuitry, to make the 24V input (18 – 36V input range) DC-DC converter modules compliant to these specifications for the 28V vehicle voltage system. Other electro-magnetic compatibility requirements, such as MIL-STD-461E and/or DEF-STAN 59-41, apply to military vehicles, but these are outside the scope of this application note. In order to meet additional conducted emission requirements an input filter, preceding the transient protection circuit covered in this application note, will be required.
Driving 300 WS2812B RGB LED’s with “the 3 cent microcontroller” – the Padauk PMS150C.
The 3 cent Padauk PMS150C is.. Interesting to say the least. First of all there’s a lot this little MCU doesn’t do. It doesn’t have a lot of code space (1K Word), it doesn’t have a lot of RAM (64 bytes) and it doesn’t even do hardware multiplication. It doesn’t have an instruction for loading data from ROM either(Though there are ways of getting around this – but that’s a subject for another post). And of course – you can only program it ONCE.
More details at ABNielsen.com.
Check out the video after the break. Continue reading “3 cent PMS150C MCU driving 300 WS2812B LED’s”
Kenneth Finnegan shared a tip on using 0603 SMDs on the .1″ perf board:
As a quick little tip, when I’m prototyping circuits on 0.1″ perf board, I like using 0603 surface mount components for all of my passives and LEDs, since they nicely fit between the pads. This way I don’t need to bother with any wiring between LEDs and their resistors, since I can just use three pads in a row to mount the LED and their corresponding current limiting resistor and just need to wire the two ends to where they’re going.
See the full post on his blog.
Implementation on ambient light and time tracking luminaires controller from MAXIM Integrated, Link here
This reference design explains how to design an intelligent lighting controller that senses and measures the ambient light level with an ambient light sensor (ALS). Equipped with a real-time clock (RTC), the controller also knows when to turn lighting on or off at specified times.
App note from MAXIM Integrated digging on the basics of CMOS analog switches and the latest improvement on them from the standard one. Link here
Integrated analog switches often form the interface between analog signals and a digital controller. With the large number of analog switches on the market today, there are many performance criteria for a product designer to consider. There are also many application-specific switch circuits that have evolved from the standard CMOS switch developed over 35 years ago.
Every Friday we give away some extra PCBs via Facebook. This post was announced on Facebook, and on Monday we’ll send coupon codes to two random commenters. The coupon code usually go to Facebook ‘Other’ Messages Folder . More PCBs via Twitter on Tuesday and the blog every Sunday. Don’t forget there’s free PCBs three times every week:
Continue reading “Free PCB coupon via Facebook to 2 random commenters”
New NXP MCUXpresso Eclipse IDE v11:
The V11 of the MCUXpresso IDE is again a big step forward: new Eclipse version and 64bit, updated ARM toolchain, extended debugging support for P&E and Segger in addition to the LinkServer connection. The Global Variables view now supports live variables and graphing for P&E and SEGGER in addition to the LinkServer connection. The new views with the Build Analysis, Image Info, Stack usage and Call Analysis are very useful. And for bare metal applications it includes a heap and stack usage view too.
More details on MCU on Eclipse.
The classic 555 timer on a breadboard:
Here, I will show how you can make your own version of the 555 timer using just NAND gates, opamps , a transistor and a few resistors! Now, you may think what is the purpose of building this when you can buy the IC at very cheap rates. The answer is, you learn electronics better, understand how the actual IC functions and improve your confidence in building electronic circuits.
More details on TheMagicSmoke blog.
Every Tuesday we give away two coupons for the free PCB drawer via Twitter. This post was announced on Twitter, and in 24 hours we’ll send coupon codes to two random retweeters. Don’t forget there’s free PCBs three times a every week:
Some stuff:
We try to stagger free PCB posts so every time zone has a chance to participate, but the best way to see it first is to subscribe to the RSS feed, follow us on Twitter, or like us on Facebook.
Adam Zeloof made his own guitar pedal based on the Zvex Fuzz Factory:
The Z.VEX Fuzz Factory is an amazing little fuzz pedal designed by musical and electrical wizard Zachary Vex. I was introduced to it through Matt Bellamy‘s unique guitar style, and fell in love with its out-of-this-world sound. While I was tempted to buy a Z.VEX original for their beautiful hand-painted cases, I decided to save a few bucks and make my own.
See the full post on his blog.
App note from ROHM semiconductor on MOSFETS and IGBTs. Link here (PDF)
Power switching devices such as MOSFETs and IGBTs are used for various kinds of power supply applications, power supply line switching components, and other power applications. In addition, the circuit topologies used are diverse, parallel and series connections are widely used, not to mention single device use. Especially in bridge circuit configuration, in which the devices are connected in series, it is common to turn on and turn off each device alternately. Due to the current flowing and the voltage change in each device, the devices greatly affect one another. In this application note, we focus on Gate-Source voltage in MOSFET bridge configuration based on one of the simplest power circuits, a synchronous rectification boost converter to understand the switching operation in detail.
Board mounting an DFN/QFN (Dual/Quad Flat-Pack No lead) application note from ON Semiconductor. Link here (PDF)
The DFN/QFN platform offers a versatility which allows either a single or multiple semiconductor devices to be connected together within a leadless package. These guidelines include printed circuit board mounting pads, solder mask and stencil pattern and assembly process parameters.
A simple digital clock with PIC16F628A + DS1307:
In this new project I am again using PIC16F628A microcontroller. The goal is simple digital clock with 7-segment LED display and the clock will have no additional functionality – no alarm, no seconds digits, no date. The latter can be added in the software though. For the RTC chip I chose DS1307. For the LED display I used Kingbright CC56-21SRWA.
More details on DIYfan blog.
Check out the video after the break. Continue reading “Simple digital clock with PIC16F628A and DS1307 and 7-segment LED display”
Here’s a great write-up on building a phase-locked inverter from mitxela.com:
The input is at 50Hz and the output is at 60Hz. So for every 5 input cycles, we want to generate 6 output cycles. We will be synthesizing a sine wave in software, and there’s no reason not to go with a conventional lookup table of 256 bytes. The PWM will be averaged out by the coils in the motor. It may even be possible to drive it with a square wave, but there is a self-starting mechanism I don’t want to interfere with. A synchronous single-phase motor normally will spin in either direction, and if you want it to spin only one way (as is the case with a clock) extra components are needed. It could be a mechanical pawl that stops it starting in the wrong direction, but the rotor spins very freely in either direction when the clock is powered off. More likely, there is a capacitor and/or additional coils which provide the shove in the right direction.
Project info at mitxela.com.
