Today I wanted to quickly calculate a truth table for a simple boolean equation. Whilst this can be done very simply on paper it becomes tedious with lots of inputs.
A quick Google search found “Logic Friday”, available at sontrak.com. Boolean operations can be described using logic gates, truth tables or an equation.
Today two sets of PCBs arrived from OSH Park. Firstly a breakout board for Kingbright 14 segment LEDs. These are great for very high brightness text display.
Secondly a small breakout board for the Maestro A2035-H GPS receiver. This is a capable GPS powered by the SiRFStar IV chipset. It supports NMEA or SPI and can update at 5Hz, which makes it an interesting GPS for sport tracking. I plan on using it for tracking go-karts around an outdoor track.
I wrote previously that I would review a graphic LCD made by dogm, which was provided by the company so I could update my ST7565 library. These can be bought from Mouser for reasonable prices.
There are a variety of different screens and various coloured stick on LED backlights, including an RGB one. Below you can see the sample GLCD on a breadboard.
It is much smaller than the other ST7565 modules I have, the whole module is 55mm by 45mm and the display area is approximately 50mm by 30mm.
I have written a simple tutorial explaining how to use the PIC fixed voltage reference (FVR) in order to calculate Vdd, using no external components.
It got a bit long for a blog post so can be found here: Measuring PIC Vdd with no external components using the FVR.
People often ask how I assemble SMD boards, the video below is sped up to 20x and demonstrates the process. It takes a few minutes to dab some solder paste on each pad, then parts are placed using anti-magnetic tweezers. Finally the whole lot is carefully put into a frying pan and heated quickly over a gas hob.
Don’t share the frying pan with anything else - you don’t want to be mixing solder and your sausages!
After some recent discussions with two friends Rich & Dave I have been playing with WebSDR, decoding all sorts of transmissions using MultiPSK. I have never been particularly interested in amateur or “ham” radio but receiving and decoding signals from around the world is a fun way to pass a cold evening.
There is lots to find: weather information, humorous IRC style chat, worldwide operators trying to reach as far as possible and even digitally coded pictures.
Today I received some prototyping boards from Mike at White Wing Logic. These are a little like stripboard/veroboard on steroids, they have footprints for a number of different surface mount parts and connectors with breakout pads. I have used breadboard or custom PCBs solely for a few years but increasingly packages are only available in surface mount.
I have made a few changes to my ST7565 library, available from GitHub.
Firstly the configuration is now broken out into a new file, so that st7565.h and st7565.c can be overwritten when the library updates without interfering with port settings. A quick fix is included for the dogm displays which appear to reverse the screen in a different way to the previous screen I tested. I will do a full review of the rather nice dogm module at a later date.
I needed a sine wave carrier for a magnetic transponder system I am working on. Various types of crystal based oscillator are available such as the Pierce, but these can be tricky to design and ensure they work correctly.
Rich suggested using a square wave oscillator with a filter to turn it into a sine wave. The filter attenuates all frequencies except the fundamental frequency, which should remove much of the square wave. Over a couple of nights I tested this in ltspice then built it on a breadboard and checked the real life results.