Programmable seven segment LED tester

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A Seven segment LED tester project from Arduino Enigma:

Here is the finished Seven Segment Tester. All of the available Arduino Nano pins, except for analog input pins A6,A7 and Serial Port pins D0 and D1 are connected. This leaves us with 18 pins to bring to the 3M Zero Insertion Force (ZIF) socket. Any display up to 9 pin DIP can be tested.
Here are some pictures of the device testing a 16 segment display, a 7 segment display and a 3 digit 7 segment display. The common cathode and common anode versions are programmed as test patterns.
Once the Arduino is programmed, the device can work standalone using a 9v battery.

More details on Arduino Enigma Machine Simulator blog.

Check out the video after the break.

63 dB step attenuator

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DuWayne published a new build:

While I was working on the power meter function for the latest version of the SNA, I used several fixed attenuators for checking linearity and calibration. It would be a lot easier if I had a variable step attenuator. I have several digital controlled attenuator modules that I bought one eBay a while ago, and I guess it is time to use some of them. There are several models available. The ones I plan on using are the simplest with only 6 control pins for a total attenuation of 31.5 dB in .5 dB steps. I am going to connect two in series with the control lines paralleled for a total of 63 dB in 1 dB steps.

See the full post on his blog.

App note: Passive entry door system with proximity sensor

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A full implementation of a keyless entry from Microchip. Link here (PDF)

The door access systems have evolved from simple physical keys to more sophisticated keyless entry systems. Now, we have a system that automatically unlocks the door when user carrying an access key approaches the door handle. As it does not require any user action this system is referred to as Passive Entry

App note: Low Power POE Flyback Converter

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App note from Microchip about their MIC2145 boost switching regulator to do POE Flayback conversion. Link here (PDF)

The MIC2145 skip mode controller is used to implement a flyback converter that is intended for use in nonisolated, low power, POE applications. The circuit has a nominal 48V input and supports the POE voltage range of 36V to 57V. The output voltage is 2.5V at 350mA.

Open source hardware ESP32-ADF

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Here’s an open source hardware development board for Espressif audio development framework, the ESP32-ADF, from Olimex:

With ESP32-WROOM-B module with 8MB RAM and 4MB of Flash, two microphones, two 3W speakers, codec, amplifier, Lipo charger, USB with programming, Audio 3.5mm jack, ESP32-ADF board offers everything you need to start playing with Espressif Audio Development Framework.

Check out the video after the break.

rePalm

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rePalm project from Dmitry.GR

As I mentioned, none of the native API of PalmOS 5.x was ever documented. There was a small number of people who figured out some parts of it, but nobody really got it all, or even close to it. To start with, because large parts are not useful to an app developer, and thus attracted no interest. This is a problem, however, if one wants to make a new device. So I had to actually do a lot of reverse engineering for this project – a lot of boring reverse engineering of very boring APIs that I still had to implement. Oh, and I needed a kernel, and actual hardware to run on.