Using DS1307 and DS3231 real-time clock modules with Arduino

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John Boxall over at Tronixstuff has posted a detailed tutorial on how to on how to use DS1307 and DS3231 real-time clock modules with Arduino:

 There are two main differences between the ICs on the real-time clock modules, which is the accuracy of the time-keeping. The DS1307 used in the first module works very well, however the external temperature can affect the frequency of the oscillator circuit which drives the DS1307’s internal counter.
This may sound like a problem, however will usually result with the clock being off by around five or so minutes per month. The DS3231 is much more accurate, as it has an internal oscillator which isn’t affected by external factors – and thus is accurate down to a few minutes per year at the most. If you have a DS1307 module- don’t feel bad, it’s still a great value board and will serve you well.

Free PCB coupon via Facebook to 2 random commenters

buspiratev383

Every Friday we give away some extra PCBs via Facebook. This post was announced on Facebook, and on Monday we’ll send coupon codes two random commenters. 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”

Soundbar design from start to finish

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Dafydd from Hacker Camp Shenzhen vol 2 works at TI and wrote this app note:

The future of consumer home audio has shifted. The priority has moved from having speakers and wires all over the living room to a single, intelligent product capable of emulating the audio experience of other multi-speaker installations. This is normally referred to as a speakerbar or its aftermarket term, a soundbar.

This article is intended to help you get started in designing your own soundbar/active speaker dock by discussing the necessary requirements in putting together the specification list. Future articles will discuss the subsequent steps, including converting a marketing specification into a block diagram, converting the block diagram into a list of devices, suggestions for layout, and software architectures.

Cheap USB LiPo charger notes

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Jim writes:

Since I use a variety of cells, I wanted to be able to charge at Chip2014under 1A. Most such charge controllers have a single resistor that programs the bulk charge current, so I looked for the datasheet to find what values I’d need for the charge currents I wanted. The chip is marked 4056ES, and there are charge controllers with that number – but they don’t match this package layout. The Ebay ad was titled “5V Mini USB 1A Lithium Battery Charging Lipo Charger Module for Arduino A866″, but I couldn’t find anything under A866, either. It says RD084DY002 on the back, but that’s not helpful either. Rats. (But see update!)

 

Hacking the HP Z800 Xeon motherboard into a standard case

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Andy Brown wrote an article detailing how to hack the HP Z800 Xeon motherboard into a standard case:

I’m not one to give up in the face of a technical challenge and besides I’d just forked out a hundred notes on the board so the rest of this article will go through all the steps in detail that you would have to do in order to get one of these beasts up and running yourself. There’s no cheaper way to get 12 cores of Xeon power under your desk.

 

PIC Micro Modbus

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Chas over at PNW/Electronics has been working on a PIC Micro MODbus project:

MODbus is a older-than-dirt communications protocol for industrial process/power controls. It’s generally seen in the wild as MODbus/RTU which is a RS-485 protocol ran at 9600 or 19200 baud. Of course there are a ton of variations and it wouldn’t be a comm protocol these days unless someone decided to make a MODbus/IP.. but that’s beyond the scope.

Continue to Update 2 – Calculating CRC and Update 3 – The 18F27J53 Port & tinyLED.

Huge saving @ Seeeday December 10th 2014 EST

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Huge saving @ Seeeday December 10th 2014 EST!

  • Up to 70% off of all items.
  • Free shipping over 3 items your purchase. (Available for Registered Air Parcel Only, Weight Less Than 2KG)
  • More than 60 items ready for additional fire sales of $0.99, $1.90, $2.90, $3.90, $4.90 and $9.90 USD;
  • Easy shop within 12 different product lines
  • All coupons are redeemable on Seeeday

Cupid Mega Remote: Killer controller

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Colin Reese blogged about his MEGA controller build:

Last we met, we built a prototype temperature wireless RF temperature controller. We got some good ideas and a Beer Fridge monitor out of the deal. We also realized, however, that we were flying pretty close to the sun in terms of the available memory we had to work with. Considering we weren’t concerned about power consumption, wanted to make our IO as flexible as possible (for example more interrupts and UARTs), we decided that a more powerful micro is in order. Enter the Moteino MEGA. Take a Moteino R4 and swap out the ATMEGA328P for a 1284P, add a reset button, and you get the Moteino MEGA. Fantastic idea. It’s a slightly larger footprint, but all progress has a price, right?

Details can be found on his Cupid Controls site.

#FreePCB via Twitter to 2 random RTs

buspiratev383

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:

  • Hate Twitter and Facebook? Free PCB Sunday is the classic PCB giveaway. Catch it every Sunday, right here on the blog
  • Tweet-a-PCB Tuesday. Follow us and get boards in 144 characters or less
  • Facebook PCB Friday. Free PCBs will be your friend for the weekend

Some stuff:

  • Yes, we’ll mail it anywhere in the world!
  • Check out how we mail PCBs worldwide video.
  • We’ll contact you via Twitter with a coupon code for the PCB drawer.
  • Limit one PCB per address per month please.
  • Like everything else on this site, PCBs are offered without warranty.

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.

First steps with the ESP8266-03 development board

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As a follow up to the “Development board for the ESP8266-03” post, Limpkin blogged about his first steps with ESP8266-03 dev board:

As mentioned in my previous blog post I was very optimistic when designing my ESP8266-03 development board and didn’t even prototype it before launching a batch in production. As I just received a few of these boards in the mail today and given that information about this module is scattered all over the internet, I’ll detail here my first steps with it…

 

Check out the video after the break. Continue reading “First steps with the ESP8266-03 development board”

Reverse engineering a Verisure wireless alarm

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Here’s an informative two-part series of posts over at FunOverIP detailing how to reverse engineer a Verisure wireless alarm.

Part 1 details the beginning steps such as finding the modules radio frequency and modulation type, analyzing the chipset datasheet and using GNU Radio. Part 2 covers more complex topics including firmware extraction from an alarm module and analysis of crypto keys.

Good coverage of an interesting use of SDR and related tools.

VHF Aircraft radio communications receiver

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Dilshan Jayakody published a new build, a VHF Aircraft radio communications receiver:

This is simple radio receiver project which is capable to receive aviation radio voice signals which are transmit between 118MHz to 138MHz in AM (A3E). We got initial idea of this project by reading Sverre Holm’s (LA3ZA) article about “cheap VHF receiver project”. Like LA3ZA’s original article this project is also based on Samsung’s KA22429 FM radio receiver IC.
KA22429 is low voltage FM radio receiver system developed by Samsung for portable radio receivers and as described by Holm’s it can push into VHF region by changing few values in its original circuit. In this project we redesign the schematic and PCB with some of those changes and now it can directly tune into aviation band with minimum number of adjustments.

All files are available on Dilshan’s elect.wikispaces.

OV7670 image sensor data capture with Atxmega32E5 without using external FIFO

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Kehribar has interfaced a OV7670 camera module with Xmegae5 microcontroller without external FIFO:

  • With current configuration, this system sends 20FPS 80×60 grayscale image data over 3Mbaud serial stream. There is 3 byte preamble {0xAA,0x55,0xAA} to indicate the start of a new image frame. Computer software / other MCU can use those bytes to sync with the data stream.
  • Utilises two EDMA channels, two event channels, two timers and one UART peripheral of the XmegaE5 microcontroller.
  • Computer software is written in C++ using OpenCV image drawing / matrix functions.
  • This project is heavily inspired by “Interfacing a cheap phone camera module to a PIC32 microcontroller” project by @mikeselectricstuff.

Via the project log forum.

Atmel releases new low power MCUs

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Atmel recently announced the release of their next generation of low power 8-bit MCUs. Promising to be pin compatible with previous ATmega family members, these “The Atmel mega168PB, mega88PB and mega48PB are available in 32-pin QFN and QFP packages with additional devices available later this year. All devices are sampling now. Production quantities for the mega168PB devices are available now while the mega88PB and ATmega48PB devices are available in February 2015.”

Atmel is making available a limited of Xplained Mini eval kits using the ATmega168 or ATmega328 available for $8.88 from the Atmel store.

The ATmega328 board’s user guide is available as a 16-page PDF.

Free PCB Sunday: Pick your PCB

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We go through a lot of prototype PCBs, and end up with lots of extras that we’ll never use. Every Sunday we give away a few PCBs from one of our past or future projects, or a related prototype. Our PCBs are made through Seeed Studio’s Fusion board service. This week two random commenters will get a coupon code for the free PCB drawer tomorrow morning. Pick your own PCB. You get unlimited free PCBs now – finish one and we’ll send you another! Don’t forget there’s free PCBs three times every week:

Continue reading “Free PCB Sunday: Pick your PCB”

Build a 16 million color WiFi-controlled LED lamp


Tom Van den Bon and Sebastian Schocke of Binary Space, a makerspace in the Vaal Triangle, have put together this build challenge for their members.

For December at Binary Space we wanted to do something a cheerful and colourful. We got together to design and build a low power LED table or ceiling lamp that connects to your home WiFi. Once assembled and connected you can change the colour tone to any one of 16 million colours from the RGB gamut.

The project is designed around a Nucleo STM32 Development Board, an ESP8266 Wifi Module and a set of WS2811 RGB LEDs, and is housed in a 3D printed enclosure.

Details can be found in their post on the Makes Htxt blog.

App note: Magnetoresistive Sensors

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Principle of operation of magnetoresistive sensors, app note from Honeywell.

Magnetoresistivity is the ability of a material to change resistance under the influence of magnetic fields. There are several different magnetoresistive effects, but Honeywell sensors use the Anisotropic Magneto Resistive (AMR) effect which occurs in ferrous materials, including Permalloy. Permalloy is an alloy of nickel and iron and has been used as a sensing material since the early part of the 20th century in transformer designs. Low sensitivity to mechanical stress coupled with high sensitivity to magnetic fields provide sensors that vart from magneto meters to automotive engine applications.

App note: Hall effect sensing and application

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Hall effect sensing introduction app note from Honeywell.

The Hall effect has been known for over one hundred years, but has only been put to noticeable use in the last three decades. The first practical application (outside of laboratory experiments) was in the 1950s as a microwave power sensor. With the mass production of semiconductors, it became feasible to use the Hall effect in high volume products. MICROSWITCH Sensing and Control revolutionized the keyboard industry in 1968 by introducing the first solid state keyboard using the Hall effect. For the first time, a Hall effect sensing element and its associated electronics were combined in a single integrated circuit. Today, Hall effect devices are included in many products, ranging from computers to sewing machines, automobiles to aircraft, and machine tools to medical equipment.

Reviving 80’s arcade, Super invaders

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Stian did restoration of 80’s arcade. He wrote a post on his blog detailing the process:

I did a visual inspection the board looking for shorts or burned out components, and replaced a few 100nF ceramic capacitors that literally had cracked and/or fallen off. I then examined the on-board power supply. It consists of four voltage regulators, two 7085s, one 7812 and a 7905. I checked the datasheets and found that they would all tolerate my 19VDC laptop supply, which I later connected to the board.
Once powered up, I probed around with my oscilloscope and thanks to geeking around with composite video signals earlier, I immediately recongized the signal and hooked the board up on my TV – and voila – a working image! The game title said “Super Invaders”. The game appered to work fine, although with a very distorted and unstable image. I wonder why.

Free PCB coupon via Facebook to 2 random commenters

buspiratev383

Every Friday we give away some extra PCBs via Facebook. This post was announced on Facebook, and on Monday we’ll send coupon codes two random commenters. 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”