Emulating a hardware ROM in real time with an STM32F4



ROM emulation using an STM32F4:

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.

Full details at Kernelcrash.com .

Bit-bang FTDI USB-to-serial converters to drive SPI devices


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. ”

See the full post on Scott Harden’s blog .

Check out the video after the break


App note: How to select an ambient light sensor for your end equipment


Another application note from Texas Instruments about ambient light sensors and how to effectively use them. Link here (PDF)

Generally, when someone thinks of trying to design a system with an ambient light sensor there are four main concerns or problems that need to be addressed. The most important features of an ambient light sensor are spectral response, power, size, and range of lux measurement.

App note: How to isolate signal and power in isolated CAN systems


CAN system isolation app note from Texas Instruments, Link here (PDF)

With the increase in the usage of signal isolation in many industrial and automotive applications, the need for isolated power has also increased. The benefits of isolation are lost if the power supplies on either side of the isolation barrier are simply shorted. At the same time, if the isolated power sub-systems are not designed carefully, it affects the overall system performance like temperature rise due to poor power transfer efficiency, data corruption due to emissions, and so on. To simplify the design process of isolated CAN sub-systems, this document provides various options (discrete and integrated) to isolate CAN signals and power.

ESP32 and the CWTD ‘Test gadget’

esp32 test gadget

DuWayne published a new build:

I have been following a series of podcasts from ‘Chatting with the Designers’  CWTD.ORG that cover building simple Arduino based test equipment.  I decided that this would make a nice way to get into development with the ESP32.  The CWTD ‘Test Gadget’ is basically an Arduino Nano with a 2 line LCD display, and a breadboard area where small modules can be plugged in to make different types of instruments.  My version will use the ESP32 and the TFT display.  I am also replacing their rotary encoder with a joystick for the user interface device.  I am bringing all the pins from the ESP32 module out to two pairs of female headers, that should allow me to plug in two small modules at the same time.

See the full post on DuWayne’s Place blog.

Siglent SDG6000X Series Arbitrary waveform generator review, teardown and experiments


A closer look at the newly released Siglent SDG6000X Series Arbitrary Waveform Generator from The Signal Path:

The full teardown of the unit reveals the internal architecture of the instrument, DAC / FPGA interconnect as well as the output amplifier structure. Although the limitations of the FPGA prevents the instrument to operate at full 2.5GSa/s in arb-mode, the instrument is capable of providing complex modulation up to the full 500MHz signal bandwidth.

More details on The Signal Path blog.

Check out the video after the break.

Transistor radio series: the AF power amp

AF Power Amp

Vasily Ivanenko @ QRPHB writes, “I sought a low distortion, single supply, AF power amplifier for my transistor radios. I’ll present my experiments, some musings, test equipment and a reference to some wonderful books & their wise author. Sadly, some amateur radio receiver builders diligently craft their RF stages, but skimp on the PA audio stage. Actually — many commercial radio designers also do this.”

More details at QRP HomeBuilder blog.

Presenting the single ESC key USB keyboard


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Glen Akins shares his latest build the single ESC key USB keyboard:

After building the “awesomely impractical” giant three-key keyboard, I decided it was time to build something a bit more practical—presenting the single ESC key USB keyboard! This keyboard has exactly one function which is to provide an optimal ESCing experience regardless of whatever keyboard you normally use. In exchange for giving up a USB port, you get a dedicated tactile, clicky Cherry MX blue ESC key.

See the full post on Photons, Electrons, and Dirt blog.

An easy way to mount DS18B20 temperature sensors


Matt wrote an article describing a technique he used to mount DS18B20 temperature sensors:

One of the biggest advantage of these sensors over I2C sensors, is that you can mount them almost anywhere. That having been said, I’ve never quite managed to come up with an elegant solution, particularly when attaching to a heatsink (for cooling applications)

More details at Matt’s Tech Pages.



Minimalistic 1D pong


Here’s a minimalistic 1D Pong game from Vagrearg:

How little do you need for a game
An exercise in futility. That is what many would call this endeavor. How few elements (signifiers and affordances) do you need to not only recognize a game for what it is, but also are able to play it?
It turns out that you only need very little to do very much.

Project info at vagrearg.org.