i2c

196 Articles

In A World Without USB…

February 19, 2025 by 26 Comments

It is easy to forget that many technology juggernauts weren’t always the only game in town. Ethernet seems ubiquitous today, but it had to fight past several competing standards. VHS and Blu-ray beat out their respective competitors. But what about USB? Sure, it was off to a rocky start in the beginning, but what was the real competition at that time? SCSI? Firewire? While those had plusses and minuses, neither were really in a position to fill the gap that USB would inhabit. But [Ernie Smith] remembers ACCESS.bus (or, sometimes, A.b) — what you might be using today if USB hadn’t taken over the world.

Back in the mid-1980s, there were several competing serial bus systems including Apple Desktop Bus and some other brand-specific things from companies like Commodore (the IEC bus) and Atari (SIO). The problem is that all of these things belong to one company. If you wanted to make, say, keyboards, this was terrible. Your Apple keyboard didn’t fit your Atari or your IBM computer. But there was a very robust serial protocol already in use — one you’ve probably used yourself. IIC or I2C (depending on who you ask).

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Close up of a typewriter annex SMS-receiver

Back To The Future Of Texting: SMS On A Panasonic Typewriter

December 18, 2024 by 4 Comments

Among us Hackaday writers, there are quite a few enthusiasts for retro artifacts – and it gets even better when they’re combined in an unusual way. So, when we get a tip about a build like this by [Sam Christy], our hands sure start itching.

The story of this texting typewriter is one that beautifully blends nostalgia and modern technology. [Sam], an engineering teacher, transformed a Panasonic T36 typewriter into a device that can receive SMS messages, print them out, and even display the sender’s name and timestamp. For enthusiasts of retro gadgets, this creation bridges the gap between analog charm and digital convenience.

What makes [Sam]’s hack particularly exciting is its adaptability. By effectively replacing the original keyboard with an ESP32 microcontroller, he designed the setup to work with almost any electric typewriter. The project involves I2C communication, multiplexer circuits, and SMS management via Twilio. The paper feed uses an “infinite” roll of typing paper—something [Sam] humorously notes as outlasting magnetic tape for storage longevity.

Beyond receiving messages, [Sam] is working on features like replying to texts directly from the typewriter. For those still familiar with the art form of typing on a typewriter: how would you elegantly combine these old machines with modern technology? While you’re thinking, don’t overlook part two, which gives a deeper insight in the software behind this marvel!

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Sniffing Around Inside A ThinkPad Battery

December 4, 2024 by 24 Comments

For most people, a battery pack that’s misbehaving simply means it’s time to get a new battery. But when the battery in their ThinkPad wasn’t able to muster up more than 20 minutes of runtime, [Shrinath Nimare] saw an opportunity to dig deeper and do a bit of investigating.

The problem seemed to be that the battery pack was reporting that it was 100% charged at just 11.7 V instead of the correct 12.3 V. As it turns out, that 11.7 V figure is only slightly above what the battery should be when its run flat — so in reality, the battery was never actually getting a charge and would report that it was dead after just a few minutes of use. But why?

With a logic analyzer attached to the pins of the battery, [Shrinath] set out to sniff its communications with the ThinkPad.  Even if it wouldn’t lead to fixing the battery pack, the information obtained would potentially be useful for other projects, such as creating a custom high-capacity LiFePO4 pack down the line.

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I2C The Hard Way

October 21, 2024 by 12 Comments

[Igor] has an AS5600 magnetic rotary encoder chip on a breakout board. Normally, you’d think that was an easy device to work with since it has an I2C interface. But [Igor] wanted to do it the hard way. What’s the hard way? By hand. He directly manipulates the clock and data lines using some push buttons. You can see how it goes in the video below.

This is possible because the controlling device — in this case [Igor] — gets to set the clock rate, and there’s no reason it has to be regular. We have to admit that it never occurred to us to do this, but we have written “bit banged” I2C-like code before.

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2024 Tiny Games Contest: A Flappy Seagull Game With Sound In Only 500 Bytes

September 12, 2024 by 4 Comments

It was probably a reasonable assumption that the “Tiny” in our recently concluded Tiny Games Contest mostly referred to the physical footprint of the game. And indeed, that’s the way most of the entries broke, which resulted in some pretty amazing efforts. [Anders Nielsen], however, took the challenge another way and managed to stuff a seagull-centric side-scroller into just 500 bytes of code.

That’s not to say that the size of [Anders]’s game is physically huge either. Flappy Larus, as he calls his game, runs on his popular 65uino platform, a 6502 microcontroller in the familiar Arduino Uno form factor. So it’s pretty small to begin with, and doesn’t even need any additional components other than the tiny OLED screen which has become more or less standard for the 65uino at this point. The only real add-on is a piezo speaker module, which when hooked up to the I2C data line happens to make reasonable approximations of a squawking seagull, all without adding a single byte of code. Check out a little game play in the video below.

Flappy Larus may be pretty simplistic, but as we recall, the game it’s based on was similarly minimalist and still managed to get people hooked. The 2024 Tiny Games contest is closed now, but if you’ve got an idea for a tiny game, we’d still love to feature it. Hit the tip line and we’ll take a look! Continue reading “2024 Tiny Games Contest: A Flappy Seagull Game With Sound In Only 500 Bytes” →

I2C For Hackers: Digging Deeper

September 5, 2024 by 20 Comments

Last time, I gave you an overview of what you get from I2C, basics like addressing, interface speeds, and a breakdown of pullups. Today, let’s continue looking into I2C capabilities and requirements – level shifting, transfer types, and quirks like combined transfers or clock stretching.

Level Shifting

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Ryobi Battery Pack Gives Up Its Secrets Before Giving Up The Ghost

August 14, 2024 by 44 Comments

Remember when dead batteries were something you’d just toss in the trash? Those days are long gone, thankfully, and rechargeable battery packs have put powerful cordless tools in the palms of our hands. But when those battery packs go bad, replacing them becomes an expensive proposition. And that’s a great excuse to pop a pack open and see what’s happening inside.

The battery pack in question found its way to [Don]’s bench by blinking some error codes and refusing to charge. Popping it open, he found a surprisingly packed PCB on top of the lithium cells, presumably the battery management system judging by the part numbers on some of the chips. There are a lot of test points along with some tempting headers, including one that gave up some serial data when the battery’s test button was pressed. The data isn’t encrypted, but it is somewhat cryptic, and didn’t give [Don] much help. Moving on to the test points, [Don] was able to measure the voltage of each battery in the series string. He also identified test pads that disable individual cells, at least judging by the serial output, which could be diagnostically interesting.  [Don]’s reverse engineering work is now focused on the charge controller chip, which he’s looking at through its I2C port. He seems to have done quite a bit of work capturing output and trying to square it with the chip’s datasheet, but he’s having trouble decoding it.

This would be a great place for the Hackaday community to pitch in so he can perhaps get this battery unbricked. We have to admit feeling a wee bit responsible for this, since [Don] reports that it was our article on reverse engineering a cheap security camera that inspired him to dig into this, so we’d love to get him some help.