Dial A For Arduino

October 9, 2021 by Al Williams 19 Comments

A lot of phrases surrounding phones don’t make sense anymore. With a modern cellphone, you don’t really “hang up” and there’s certainly no “dial” to be had. However, with [jakeofalltrades’] project, you can read an old-fashioned phone dial using an Arduino.

The idea behind a phone dial is actually pretty simple. When you pull the dial back to the stop using one of the numbered holes and release it, it causes a switch to open and close the same number of times as the hole you selected. That is, if you pull back the 5 hole, you should get 5 switch closures. The duration of each switch event and the time between switch events is a function of the speed the dial moves because of its internal spring. The zero hole actually produces ten pulses.

There are standards for how precise the timing has to be, but — honestly — it’s pretty loose since these were not made to be read by precise microcontroller timers. In the United States, for example, the dial was supposed to produce between 9.5 and 10.5 pulses per second, but the equipment on the other end would tolerate anything from 8 to 11.

Even if you don’t want a rotary dial in your next project, the code has some good examples of using ATmega328 timers that you might find useful in another context. However, a dial would add a nice retro touch to any numeric input you might happen to need.

If you need project inspiration, how about a volume control? Or, why not a numeric keypad?

Build Yourself A Nifty Cable Smartphone Mount

September 5, 2021 by Lewin Day 6 Comments

Smartphones have supplanted cameras in day to day use for the vast majority of purposes. However, unlike cameras, they don’t come with tripod mounts or any real good way of holding them in a set position. [Mrballeng] has built an excellent mount, however, that uses cable to hold a smartphone in all manner of positions, for photography or other purposes.

The mount relies on vinyl-coated steel cable. Upon this cable are slotted four blocks that are 3D printed out of resin. The blocks are also fitted with strong magnets. This allows them to be positioned along the vinyl cable while sticking themselves in place thanks to the magnetic attraction to the steel core. The blocks can also be used to attach the cable to magnetic objects like drywall screws or light fittings.

Using the mount is simple. The cable is wrapped around the phone and the blocks cinched up to hold it in place. Then, the magnets in the blocks can be used to hold the phone to walls or other surfaces.

It’s a tidy build, and one we can imagine using regularly if we had one. Of course, there’s no reason you couldn’t produce the parts on a more common filament-based printer, either. We’ve seen some other great smartphone photography hacks too, like this mod that lets you use your phone as a microscope for under $10. Video after the break.

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Pining For A De-Googled Smartphone

September 2, 2021 by Bryan Cockfield 89 Comments

Last summer in the first swings of the global pandemic, sitting at home finally able to tackle some of my electronics projects now that I wasn’t wasting three hours a day commuting to a cubicle farm, I found myself ordering a new smartphone. Not the latest Samsung or Apple offering with their boring, predictable UIs, though. This was the Linux-only PinePhone, which lacks the standard Android interface plastered over an otherwise deeply hidden Linux kernel.

As a bit of a digital privacy nut, the lack of Google software on this phone seemed intriguing as well, and although there were plenty of warnings that this was a phone still in its development stages it seemed like I might be able to overcome any obstacles and actually use the device for daily use. What followed, though, was a challenging year of poking, prodding, and tinkering before it got to the point where it can finally replace an average Android smartphone and its Google-based spyware with something that suits my privacy-centered requirements, even if I do admittedly have to sacrifice some functionality.

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Arduino Caller ID Display Is Better Late Than Never

August 20, 2021 by Tom Nardi 12 Comments

It’s no secret that the era of the landline telephone is slowly coming to a close. As of 2020, it was estimated that less than half the homes in America still subscribed to plain old telephone service (POTS). But of course, that still amounts to millions upon millions of subscribers that might get a kick out of this Arduino caller ID developed by [Dilshan Jayakody].

HT9032D caller ID decoder board — The completed HT9032D board.

Truth be told, until this point, we hadn’t really given a lot of thought to how the caller ID system works. But as [Dilshan] explains, you can actually pick up a dedicated IC that can decode incoming caller data that’s sent over the telephone line. In this case he’s using a Holtek HT9032D, which comes in a through-hole DIP-8 package and can be picked up for around $2 USD. The chip needs a handful of passives and a 3.58 MHz crystal to help it along on its quest, but beyond that, it’s really just a matter of reading the decoded data from its output pin.

To display the caller’s information, [Dilshan] is using an Arduino Uno and common 16×2 HD44780 LCD. As a nice touch, the code will even blink the Arduino’s onboard LED when you’ve missed a call. As a proof of concept there’s been no attempt to condense the hardware or ditch the breadboard, but it’s not hard to imagine that all the components could be packed into a nice 3D printed enclosure should you want something a bit more permanent.

We’ve seen caller ID data being collected in previous projects, but they used a USB modem combined with a software approach. We really like the idea of doing it with a cheap dedicated IC, though we’ll admit this demonstration would probably have been a bit more exciting a decade ago.

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The Hidden Sounds Of The Past

July 18, 2021 by Matthew Carlson 20 Comments

If you stop to think, the number of pre-recorded voices and sounds you might hear on an average day might number in the hundreds. Everything from subway announcements, alerts on your phone, to sound effects at Disneyland is a sound that triggers in response to an event. [Techmoan] came across a device that many of us have interacted with, but likely never seen: a humble Sontranic 9A Announcer.

In their heyday, these sorts of devices formed the backbone of audio feedback. Messages from Father Christmas were recorded and could be reached when calling a number. Sound effects in theme parks that were activated when a ride activated some hidden switch. Anything where the sound effect needed to play on some sort of trigger.

An interesting thing to note is that this is not a reel-to-reel system. The tape is of the standard 1/4″ magnetic variety, perhaps a little thicker for extra durability. It instead sits in the top of the machine; coiling and uncoiling like a two-dimensional lava lamp. Additionally, there’s nothing clever about detecting the beginning or end of the audio loop (as there were four copies of the same recording on this particular tape). In fact, everything about this machine speaks of reliability as the most important design consideration. A reel-to-reel system would just add more points of failure.

After a little bit of diagnosing, [Techmoan] managed to get the device running again and found the message on the tape to be from the phone system, informing the listener that the line is no longer in service. This banal message is perhaps the best testament to the ubiquity of devices like these.

Perhaps in the future, we’ll see an instrument like this magnetic tape-based one created from a similar machine to the one [Techmoan] found.

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How To Drive Smartphone Screens Over HDMI

July 5, 2021 by Lewin Day 22 Comments

Compared to most small LCDs sold to makers, smartphone screens boast excellent color, brightness, and insanely high resolution. Unfortunately, driving them is rarely straightforward. In an attempt to make it easier, [peng-zhihui] set about developing tools to allow such screens to be driven from a simple HDMI feed. For those whose Chinese is a little rusty, the Google Translate link might prove useful.

The first attempt was using Toshiba’s TC358870XBG ASIC, capable of driving screens over MIPI DSI 1.1 from an HDMI input. [peng-zhihui] designed a simple test module for the chip based on the company’s evaluation board design, with [ylj2000] providing software to help get that solution off the ground.

However, for now that solution is imperfect, so [peng-zhihui] also experimented with the Longxun LT6911 HDMI to MIPI driver. While cheap, information on the part is scarce, and the company’s own source code for using the hardware is only accessible by signing an NDA. However, [peng-zhihui] made pre-compiled firmware available for those that wish to work with the hardware.

[peng-zhihui] has put these learnings to good use, building a power bank with a MIPI screen using what appears to be the Longxun chip. The device can supply power over USB and also act as an HDMI display.

While it’s early days yet, and driving these screens remain difficult, it’s great to see hackers getting out there and finding a way to make new parts work for them. We’ve seen similar work before, using an FPGA rather than an off-the-shelf ASIC. If you’ve found your own way to get these high-end displays working, be sure to drop us a line!

[Thanks to peterburk for the tip!]

LoRa Messenger In Nokia’s Shell

June 26, 2021 by Jenny List 30 Comments

The arrival of LoRa a few years ago gave us at last an accessible licence-free UHF communication protocol with significant range. It’s closed-source, but there are plenty of modules available so it’s found its way into a variety of projects in our community over the years. Among them we’ve seen a few messaging devices, but none quite so slick as [Trevor Attema]’s converted Nokia E63 BlackBerry-like smartphone. The original motherboard with its cellphone radio and Symbian-running processor have been tossed aside, and in its place is a new motherboard that hooks into the Nokia LCD, keypad, backlighting and speaker. To all intents and purposes from the outside it’s a Nokia phone, but one that has been expertly repurposed as a messenger.

On the PCB alongside a LoRa module is an STM32H7 microcontroller and an ATECC608 secure authentication chip for encrypted messages. It’s designed to form a mesh network, further extending the range across which a group can operate.

We like this project for the quality of the work, but we especially like it for the way it uses the Nokia’s components. We’ve asked in the past why people aren’t hacking smartphones, but maybe we’re asking the wrong question. If the smartphone as a unit isn’t useful, then how about its case, components, and form factor? Perhaps a black-brick Android phone will yield little, but the previous generation such as this Nokia use parts that are easy to interface with and well understood. Let’s hope it encourages more experimentation.