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Machina Speculatrix

Electronics, robotics, home automation, hacking and more. The lab notebook of an amateur meddler who likes playing with things until they work — or blow up.

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    Debouncing fun with Schmitt triggers and capacitors

    Debouncing fun with Schmitt triggers and capacitors

    The humble switch is a treacherous device that needs to be tamed.
    Go to the profile of Mansfield-Devine
    Mansfield-Devine
    May 14
    Fun with chips: MC1441 bit rate generator

    Fun with chips: MC1441 bit rate generator

    Playing with the technology of the past gives you a deeper understanding of how it works, and an appreciation for what we have today.
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    Mansfield-Devine
    May 7
    A beginner’s experience of CUPL and CPLDs

    A beginner’s experience of CUPL and CPLDs

    Making your own logic chips has a lot to recommend it. You just need to get to grips with the language.
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    Mansfield-Devine
    Apr 28
    Programming
    AVR Basics: Receiving I2C data

    AVR Basics: Receiving I2C data

    Getting information back from a peripheral device is a key part of the I2C protocol. Let’s see how to do it.
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    Mansfield-Devine
    Apr 23
    AVR Basics: Transmitting across I2C

    AVR Basics: Transmitting across I2C

    The I2C protocol is all about communicating. So let’s take a look at how you send data.
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    Mansfield-Devine
    Apr 19
    AVR Basics: Getting started with I2C

    AVR Basics: Getting started with I2C

    Being able to communicate with other devices opens up a world of possibilities — if you know what’s going on.
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    Mansfield-Devine
    Apr 14
    Retrocomputing
    From the archive: Cambridge Computer Z88 review

    From the archive: Cambridge Computer Z88 review

    Clive Sinclair always aimed for the stars. The Z88 was a classic example of how he just failed to reach them.
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    Mansfield-Devine
    Apr 21
    From the archive: Olivetti Quaderno review

    From the archive: Olivetti Quaderno review

    This attempt to put a lot of computing capability into a small package was bold. But the result proved too fragile.
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    Mansfield-Devine
    Apr 15
    From the archive: Amstrad PPC 640 review

    From the archive: Amstrad PPC 640 review

    This was one of the strangest PCs I ever used. Luckily, I didn’t have to use it for long.
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    Mansfield-Devine
    Apr 2
    Microcontrollers
    AVR basics: Using the ATMEGA SPI bus

    AVR basics: Using the ATMEGA SPI bus

    Once you have the Serial Peripheral Interface (SPI) set up on your microcontroller, putting it into action is easy.
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    Mansfield-Devine
    Mar 31
    AVR basics: SPI on the ATMEGA

    AVR basics: SPI on the ATMEGA

    The Serial Peripheral Interface (SPI) on AVR microcontrollers is very versatile, once you understand it.
    Go to the profile of Mansfield-Devine
    Mansfield-Devine
    Mar 29
    AVR basics: pin change interrupts

    AVR basics: pin change interrupts

    Interrupts are extremely useful in micocontroller applications. And they’re easier to use than you might think.
    Go to the profile of Mansfield-Devine
    Mansfield-Devine
    Mar 23
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