For years I’ve followed the “uRadMonitor”, a device that does air quality monitoring and radiation monitoring. I’ve played with geiger counter projects before and frankly found them to be not very interesting. However, the idea of monitoring air quality is something that seemed like it might yield interesting data. For example, as I’ve started to become involved in 3D printing, it would be useful to see whether or not 3D printing affected the air quality. It would also be useful to correlate my results with what my region reports for outdoor air quality.
In this project we build simple I2S stereo decoder with amplifier. To decode I2S data we use Princeton Technologies PT8211 16bit DAC. KA2206 audio power amplifier is used as driver stage of this system.
Structure of this I2S amplifier is self-explanatory from the schematic. We select PT8211 and KA2206 combination due to lower cost and availability. Unfortunately PT8211 DIP package is not available in local market and we use SO package in our prototype. We design PCB for the DIP packages, and therefore we solder PT8211 SO package to PCB using “SO8 to DIP8” converter.
The implementation is simple genius. It’s a browser that starts up full screen (kiosk mode) and just sits there and updates occasionally. DakBoard provides the private webpage and tools to make that happen. You can certainly build this yourself with any number of open source tools. I chose DakBoard because it was simple, beautiful, and I was able to get the whole thing done in less than an hour. I’m sure I’ll spend many hours tweaking it through. There’s also the very popular MagicMIrror platform, so lots of choice and power in this space!
Above you can see my prototype. I’m using a 4.2″ e-Paper display from Gooddisplay, together with the Waveshare breakout board. I have a couple of ENS1J-B28-R00128 optical encoders that I attained on eBay. I specifically chose these encoders instead of traditional electro-mechnical encoders due to the high numbers of pulses per revolution. A typical electro-mechanical encoder will net about 24 pulses per revolution. The optical encoders I bought on ebay are 128 pulses per revolution. Our 4.2″ ePaper has 400×300 pixels. To traverse the major axis would require 16 full turns of the electromechical encoder but only 3 turns of the optical encoder.
The hardware is so simple that there’s not much more to say. The encoders are connected to GPIO pins of a Raspberry Pi. Note that there are resistors inline on the encoder outputs as the encoders are 5V and the Raspberry Pi uses 3.3V GPIO. The e-ink display is connected to the SPI bus.
See the full post on his blog here and the GitHub repository here.
A few days ago I started playing with some idea I had from a few weeks already, using a Raspberry Pi Zero W to make a mini WiFi deauthenticator: something in my pocket that periodically jumps on all the channels in the WiFi spectrum, collects information about the nearby access points and their connected clients and then sends a deauthentication packet to each one of them, resulting in some sort of WiFi jammer on the 802.11 level. As an interesting “side effect” of this jammer (the initial intent was purely for the lulz) is that the more it deauths, the higher the changes to also sniff WPA2 handshakes.
So if you have been following my blog lately you may have noticed me rambling on about trying to get a Xbox 360 chat pad and an ps3 keypad working with a raspberry pi to make a portable terminal. I have finally finished my quest so join me below to see how I did it
This tutorial is inspired by dg0opk’s videos and blog post on monitoring QRP with single board computers. We’ll show you how to set up a super cheap QRP monitoring station using an RTL-SDR V3 and a Raspberry Pi 3. The total cost should be about US $56 ($21 for the RTL-SDR V3, and $35 for the Pi 3).
With this setup you’ll be able to continuously monitor multiple modes within the same band simultaneously (e.g. monitor 20 meter FT8, JT65+JT9 and WSPR all on one dongle at the same time). The method for creating multiple channels in Linux may also be useful for other applications. If you happen to have an upconverter or a better SDR to dedicate to monitoring such as an SDRplay or an Airspy HF+, then this can substitute for the RTL-SDR V3 as well.
If you spend a lot of time building things with a raspberry pi you will eventually run into the problem that you have booted your pi it’s not plugged into a tv/monitor and it’s not connected to wifi. You don’t want to just turn it off because it could corrupt the sd card so what do you do. I recently ran into this problem but luckily I had a serial adaptor on hand to hook up and tell my pi to turn off.
See the full post on his blog and the GitHub repository here.
The Raspberry Pi’s 40-pin GPIO connector often gets overlooked. Typical Pi projects use the hardware as a very small desktop PC (RetroPie, Pi-hole, media center, print server, etc), and don’t make any use of general-purpose IO pins. That’s too bad, because with a little bit of work, the Raspberry Pi can make a powerful physical computing device for many applications.