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

Raspberry Pi shares HDMI with Arduino

This is not a first time when Raspberry Pi is used as extension board for Arduino. You may ask why use Arduino at all when RaspPi already has several times more power to do these task? The reasons may vary but most common are: lack of analog input, rich code base and probably comfort of usage. Anyway let see how Raspberry Pi HDMI is used by Arduino. Practically there is no big secret – Raspberry Pi as server is reading commands from serial pins. Python based server script reads and interprets incoming commands and then draws graphics on 500×500 view-port. Arduino in other hand simply sends commands with coordinates via serial port. For instance command “draw 5 15 10 10” paints a 10×10 rectangle at point (5,15). Actually you even don’t need Arduino to send commands. Any serial terminal can be used to send drawing commands. Continue reading

Interfacing 1-wire devices to Raspberry Pi

Raspberry Pi 1-wire interface

There are lots of great devices that need 1-wire interface. They can be temperature sensors (popular DS18S20), RTC and many more. Raspberry Pi doesn’t come with 1-wire interface, so in order to use it you need to emulate through I/O pins or use some sort of expander. Tommi suggests using old Hobby Boards 6-channel 1-wire master hub that can be connected to RasPi using serial interface. a little hack is needed in order to connect hub to Raspberry Pi. The problem is that hub already has a MAX232 chip level converter. So it has to be removed so DD2480B had direct link to Raspberry Pi board. Another part is Raspberry Pi software that controls hub over serial port. Tommi found a tutorial from internet and followed it to implement his program.   Continue reading

Open source laptop build

Open source laptop

Computer is pretty complex device that can do a lot, but seems not enough. This is why Bunnie Huang has started an open source laptop. He packed a lot of features in to it that sounds like a candy for any hacker. And so it features a Quad core ARM Cortex A9 CPU running at 1.2GHz, several memory types; bootable microSD, SD, DDR3-1066 SO-DIMM up to 4GB, SATA-II. Probably most exciting here is FPGA next to CPU. It takes care of most hackable interfaces like 8 digital and 8 analog I/Os . Additionally it can drive 8 servos. There is a Raspberry Pi compatible interface header. Other standard stuff like USB, audio, WiFi header, LCD connector, UART ports, HDMI are as you would expect on any laptop. There are couple Ethernet ports available – 1Gbit and 100Mbit. Power supply is designed on separate board and can be connected through battery board interface. Battery interface board was designed to support battery packs used by RC enthusiasts up to 4S1P (4 series cells). They are cheap, they support super fast charging. Laptop… Continue reading

Raspberry Pi based atmosphere pollution meter

Raspberry Pi atmosphere monitor

Paris famous pollutant is NO2 gas so this Raspberry Pi monitor was born to keep track of concentration change. The idea was to make portable sensor box so it is powered from 8Ah battery backpack used to recharge other devices like iPhone. But most time it stays connected to power source like wall adapter. Since RasPI doesn’t have analog input there is a small custom ADC board attached to I/O which takes readings from AlphaSense B4-series analog sensor. Raspberry PI simply reads sensor data and sends it via GPRS dongle. Using only NO2 sensor would be too much of overkill, so there are intentions to add more sensors including O3 and SO2. And there is still plenty of room for upgrades. Continue reading

Quadcopter with Raspberry Pi brain

Quadcopters are fun toys and also a serious gear in many areas. These flying machines became pretty standard – four motors with individual drag force control, roll, pitch and yaw gyros and of course MCU that takes care of flight stability. Usually there are low level microcontrollers like AVR that can keep up with sensor readings, motor control and accepting RC commands. But since small and cheap Linux boards became available – Linux tries to take over flight control. Linux is not a real time operating system. So it is hard to ensure that it will react to readings as you would expect. But there are techniques to reach timed actions. Raspberry Pi is too powerful to use only for reading gyros and driving motors. Having Linux on board gives lots of free space to do lots fun like web video stream, run SSH with wireless interface or do some AI flight. Continue reading

Audiobook reader for visual impaired

Visual impaired people have limited access to real world good. One of them are books. You cannot pic any and read. Michael happens to have a 90 year grandma who can’t read for same reasons so he decided to make a nice gift for her upcoming birthday. So he came up with audiobook reader device based on Raspberry Pi. The main goal was to make it super duper simple to use. So one button seemed enough for operating. The whole secret lies within. program is written using Python script which takes care of reading audio book from SD card. Following button clicks, remembering last read position and copying new books once USB thumb drive is attached. User only has to click button once to continue reading and click again to pause. For plauing audio, mpd – music player daemon is used which supports multiple formats including MP3, Ogg Vorbis, MP4/AAC, MP2, FLAC, wave and couple more. Continue reading