Turn-key PCB assembly services in prototype quantities or low-volume to mid-volume production runs

SlightBox extends display with light effects

Computer monitor is pretty strict device – is displays information withing its frame. Outside and behind its dark. To change that Sebastien has been working on several versions of SlightBox projects where it allows playing light effects behind screen that extends on-screen effects and somewhat removes limits between screen and outside world. Video demonstration speaks for itself. Watching movies and playing games become different with those effects. The heart of this system is Raspberry Pi which does video signal analysis and determines color pixels from captured frames. Python script uses OpenCV library to do this task. Once color data is gathered, it is sent over SPI to LPD8806 LEDs behind screen. Since analyzing HDMI signals is quite tricky, he split HDMI signal where one was converted to S-video which then was fed to Raspberry Pi with STK1160 adapter. Raspberry pi also has a standard LCD for fast control and monitoring parameters. Infrared channel allows remote control of SlightBox. Raspberry Pi also allows configuring devices via web interface. So this is fun device that vivid and extend any HDMI screen at… Continue reading

Doorbell that takes photos with push-messages

Raspberry Pi is great for doing crazy setups. Being Linux based platform it can take photos, send emails and other messages over internet. Deddies Lab have shared his interesting setup, where he placed a webcam at the front door and when someone pushes doorbell message with photo footage is sent. First of all he hacked in to wireless doorbell where he was able to capture button press with Raspberry Pi GPIO. Then he wrote a simple Python script to send push message with date and time on event. During building there came a thought that seeing message isn’t enough as there is no info on who was at the door. The next thing he added was Logitech C270 webcam which was configured to capture snapshots and short movies. Again, python script composed email message with images and videos attached. From this point you could start your own modifications of this system. First of all replace webcam with Raspberry Pi camera and have even more options in capturing images and videos. You could expand functionality by adding motion detector and capture… Continue reading

Comparing Linux boards for hobbyists

Hobbyists love Linux powered development boards, because they give lots of flexibility, network connectivity and other benefits OS can give. Linux driven development boards are great, because they already have I/O pins to interface physical world and build project at different level. Market already have over dozen great Linux-based development boards and sometimes you may get stuck thinking which is best to start with. We all are familiar with Raspberry Pi, but don’t get excited, and think your needs first before purchase. Tony Dicola, recently have made a comparison of four common Linux-based development boards: Arduino Yun, Beaglebone Black, Intel Galileo and Raspberry pi. He listed most of their parameters in to table so you could clearly compare them side by side. Then he takes to next part – performance test. He runs nbench tool, which was developed to measure performance of Pentium class computers. It is obvious even from parameter list that Beaglebone black and Raspberry Pi takes leading positions. Also he measures power usage when idling and running benchmark Raspberry Pi model A leads by maxing at 150mA.… Continue reading

Raspberry Pi clone wars begins

For quite long time Raspberry Pi was the only platform that was using BCM2835 processor. But recently it started selling it to anyone that opened gate for Rpi clones. So it seems that one of the first ones is ODROID-W miniature board. It is compatible with Raspberry Pi in several ways. Forst of all it carry same GPIO layout for connecting existing modules. Of course it doesn’t have pinheaders soldered to keep it’s initial profile low. It features same processor and memory as Raspberry Pi, so it can run any Rpi OS. Being small size allows it to be used as wearable electronics. To make things more easy, there are several additions made. First of all it has Li Polymer battery connector. Also board includes RTC chip with backup battery connector as well. To keep low profile there is no Ethernet connector, the HDMI port was replaced with Micro HDMI. It still has camera interface, but no display interface which still doesn’t have its module. The list continues with built in DC/DC step-down converter also with DC/DC step-up converter for… Continue reading

Hacking wireless soil moisture sensor

Most of the effort in the gardening goes to keeping plant soil moisture at right level. Human cannot always be there and check it all the time. This is why in most cases moisture sensors are used that alert when plant needs watering. You can find cheap ready made solutions that beeps when there is water needed, but also there are more complex sensors with wireless data transfer. Wireless data is gathered in to nice receiver which can be hung somewhere inside. You can get those for about $10. So Ray decided to dig in to those and see if wireless sensors can be used as generic sensors for interfacing with Arduino or Raspberry Pi. He found that Springfield 91746 Digital Soil Moisture Meter and Freeze Alert sensor communicates at popular 433MHz frequency that can be received with cheap RF 433MHzreceiver and then decoded in to real data that can be further used in your own project. Using Raspberry Pi it becomes easy to write a simple script that would log soil moisture data in to database that could be… Continue reading

Building ADC for Raspberry Pi

Raspberry Pi lacks ADC functionality that is really necessary when building real world applications. The standard way-out of this situation is to attach external ADC chip that talks to RasPi via SPI or I2C interface. But if you need something that is closer to native peripheral, then take a look at Hussam solution where he builds ADC with comparator circuit. This solution isn’t something new and was used in recent microcontroller circuits where ADC were needed. Anyway this circuit is useful in many ways – first of all it performs ADC. Second is more educational – it simply reminds (or teaches) how ADC work. Functionality of the circuit is rather simple – it utilized two Raspberry Pi pins where one generates PWM and along with RC filter it gives some voltage level which then is compared to analog voltage source. Code takes care of generating PWM and reading comparator values and this operation is called ‘successive approximation algorithm’. He writhes a thorough explanation on how it works and provides source code to try it out. Currently such ADC was able… Continue reading