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.
I’m glad to announce the successful reverse engineering of Sega’s System 16 cpu security modules. This development will enable collectors worldwide preserving hardware unmodified, and stop the general discarding of Hitachi FD modules.
The project is right now involving external testers so expect further details and full disclosure over the coming weeks.
David Zweben published a project writeup showing how he built a Neopixel clock powered by an Arduino Pro Mini clone and a real time clock module:
After building my first Neopixel Clock, I decided I needed one for myself. There was no way I was going to solder 90 lengths of wire onto 180 tiny pads again, though, so I knew I needed to design a custom PCB. This necessitated a redesign of the entire clock, focused around making it as easy as possible to assemble.
A quick lookup on the ESD protection evolution of ICs in this app note from ON Semiconductor. Link here (PDF)
The stunning progress in integrated circuit capability over the last 40 years is most succinctly expressed by Moore’s Law; “Every 2 years the number of transistors that can be economically manufactured in an integrated circuit will double”. The secret to this success has been the shrinking of integrated circuit feature sizes in all three dimensions. To maintain circuit reliability with the smaller dimensions the operating voltage of integrated circuits has been steadily declining. This trend will continue in the future, as documented in the International Technology Roadmap for Semiconductors. As the working voltage for integrated circuits decreases the voltage at which circuit damage can occur also decreases.
The move to smaller geometries has also prompted fundamental changes in IC technologies that have had an adverse effect on the intrinsic ability of the technologies to survive ESD stress. A prime example is the evolution of nMOS transistors in CMOS technologies.
Different TVS configuration usage app note from ON Semiconductor. Link here (PDF)
Transient Voltage Suppression (TVS) protection is important because EMI and ESD can disturb the operation of the system, produce permanent damage or cause latent damage that will eventually cause a failure. Avalanche TVS diodes and diode arrays are available in a number of different circuit configurations to protect electronic circuits from surge voltages. This document will analyze the attributes and trade-offs of different circuit configurations created with avalanche TVS and diode array protection devices.
I remember reading dhole’s Emulating a GameBoy Cartridge with an STM32F4 some time ago thinking that it had a lot of applications with respect to old computers. In that article a STM32F4 microcontroller ‘pretends to be a ROM chip for a gameboy’. At the start of a bus cycle, an interrupt is triggered in the STM32F4, it then reads the address bus of the gameboy’s 6502, checks the gameboy’s read/write line(s) and pulls data from its internal Flash and presents it onto the data bus long enough for the gameboy to read it, then tristates the databus. There are no wait states. It does this all within the 1000ns of the 1MHz Gameboy CPU clock. For all intensive purposes the gameboy thinks it has a real rom chip attached.
Scott W Harden writes , “The FT232 USB-to-serial converter is one of the most commonly-used methods of adding USB functionality to small projects, but recently I found that these chips are capable of sending more than just serial signals. With some creative programming, individual output pins can be big-banged to emulate a clock, data, and chip select line to control SPI devices.
This post shares some of the techniques I use to bit-bang SPI with FTDI devices, and some of perks (and quirks) of using FTDI chips to bit-bang data from a USB port. ”
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