Pulse Oximetry Sensor Judges Your Coffee Roast

October 22, 2020 by Donald Papp 24 Comments

Breakout board for the MAX30101, which [Zach] used as the basis of his roast gauge. The sensor is at the top edge of the board.

Parts designed and marketed for a specific application can nevertheless still be useful in other ways, and whenever that happens, it’s probably the start of a pretty good hack. Using a sensor for something other than its intended purpose is exactly what [Zach Halvorson] did to make the Roast Vision device, which uses the MAX30101, a sealed optical sensor intended mainly for pulse oximetry and heart-rate monitoring.

[Zach] is instead using that sensor to measure the roast level of coffee beans, and assign a consistent number from 0 to 35 to represent everything from Very Dark to Very Light. Measuring a bean’s roast level is important to any roaster seeking accuracy and consistency, but when [Zach] found that commercial roast gauges could easily cost over a thousand dollars, he was sure he could do better.

[Zach] settled on using a Sparkfun MAX30101 breakout board to develop his device, and Sparkfun shared an informative blog post that demonstrates how making hardware and tools more accessible can help innovative ideas flourish. The Roast Vision device has a 3D printed enclosure, and a simple top-loading design with an integrated sample cup makes it easy to use. One simply puts about a teaspoon of finely-ground coffee into the sample cup, and the unit provides a measurement in a couple of seconds. Fortunately the sensor works just fine though an acrylic window which means the device can be sealed; a handy feature for a tool that will spend a lot of time around ground coffee.

The joys of fresh roasted coffee is something that is perfectly accessible to those making small batches at home. There are commercial options for small roasters of course, but should you wish to go the DIY route, check out our own Elliot Williams’ guide on making a low-cost DIY roaster.

New Raspberry Pi 4 Compute Module: So Long SO-DIMM, Hello PCIe!

October 19, 2020 by Elliot Williams 151 Comments

The brand new Raspberry Pi Compute Module 4 (CM4) was just released! Surprised? Nope, and we’re not either — the Raspberry Pi Foundation had hinted that it was going to release a compute module for the 4-series for a long while.

The form factor got a total overhaul, but there’s bigger changes in this little beastie than are visible at first glance, and we’re going to walk you through most of them. The foremost bonuses are the easy implementation of PCIe and NVMe, making it possible to get data in and out of SSDs ridiculously fast. Combined with optional WiFi/Bluetooth and easily designed Gigabit Ethernet, the CM4 is a connectivity monster.

One of the classic want-to-build-it-with-a-Pi projects is the ultra-fast home NAS. The CM4 makes this finally possible.

If you don’t know the compute modules, they are stripped-down versions of what you probably think of as a Raspberry Pi, which is officially known as the “Model B” form-factor. Aimed at commercial applications, the compute modules lack many of the creature comforts of their bigger siblings, but they trade those for flexibility in design and allow for some extra functionality.

The compute modules aren’t exactly beginner friendly, but we’re positively impressed by how far Team Raspberry has been able to make this module accessible to the intermediate hacker. Most of this is down to the open design of the IO Breakout board that also got released today. With completely open KiCAD design files, if you can edit and order a PCB, and then reflow-solder what arrives in the mail, you can design for the CM4. The benefit is a lighter, cheaper, and yet significantly more customizable platform that packs the power of the Raspberry Pi 4 into a low-profile 40 mm x 55 mm package.

So let’s see what’s new, and then look a little bit into what is necessary to incorporate a compute module into your own design.

Continue reading “New Raspberry Pi 4 Compute Module: So Long SO-DIMM, Hello PCIe!” →

Spare Parts Express

October 17, 2020 by Elliot Williams 33 Comments

I’ve got spare parts, and I cannot lie.

This week I’m sending out two care packages to friends and coworkers because I’ve got too many hackables on hand, and not enough time to hack them all. One is a funky keyboard, and the other is an FPGA dev board, but that’s not the point. The point is that the world is too interesting, and many of us have more projects piled up in the to-do box, with associated gear, than we’ll ever have time to complete.

Back in the before-times, we would meet up, talk about our ongoing hacks, and invariably someone would say “oh you need an X, I’ve got half a box of them” and send you one. Or maybe you’d be the one with the extra widgets on hand. I know I’ve happily been in both positions.

Either way, it’s a win for the giver, who gets to take a widget off the widget pile, for the receiver, who doesn’t have to go to the widget store, and for the environment, which has to produce fewer widgets. (My apologies to the widget manufacturers and middlemen.)

This reminded me of Lenore Edman and Windell Oskay’s Great Internet Migratory Box Of Electronics Junk back in the late aughts. Trolling through the wiki was like a trip down memory lane. This box visited my old hackerspace, and then ended up with Bunnie Huang. Good times, good people, good hacker junk! And then there’s our own Brian Benchoff’s Travelling Hacker Box and spinoffs.

These are great and fun projects, but they all end up foundering in one respect: to make sense, the value of goods taken and received has to exceed the cost of the postage, and if you’re only interested in a few things in any given box, that’s a lot of dead weight adding to the shipping cost.

So I was trying to brainstorm a better solution. Some kind of centralized pinboard, where the “have too many h-bridge drivers” folks can hook up with the “need an h-bridge” people? Or is this ad-hoc social network that we already have working out well enough?

What do you think? How can we get the goods to those who want to work on them?

Rolling Your Own TiVo WiFi Adapter

October 14, 2020 by Tom Nardi 16 Comments

The only thing more surprising than finding out TiVo actually put out a new 4K set-top box recently is learning that somehow they didn’t bother to build WiFi into the thing. You’re forced to buy a special wireless adapter to the tune of $60 USD to add the feature. We’d make a joke about the company living in the past, but frankly, it would be too easy.

Having to buy just one of these expensive dongles in 2020 would be insulting enough, but TiVo superfan [xxbiohazrdxx] needed four of them. Rather than hand nearly $250 to the antennae-headed overlords, they decided to reverse engineer the adapter and produce their own low-cost version. While the final result might not be as slim and svelte as the original, it does come in at less than 1/4 the price.

Operating under the assumption that the TiVo would only talk to a WiFi adapter based on the same Broadcom BCM43569 chipset used in the official one, [xxbiohazrdxx] started by trying to find a standard USB dongle that might be a drop-in replacement. Unfortunately, it looks like this particular chip was almost exclusively used in proprietary applications, most commonly as a WiFi board inside of smart TVs. But as it turns out, that wasn’t necessarily a deal breaker.

After some searching, [xxbiohazrdxx] eventually found the promising CyberTAN NU361-HS board. Not only was it based on the right chipset and ran from 5 volts, but its FCC ID entry had a complete pinout for the connector. This particular WiFi module is used in a number of budget TVs and is widely available as a spare part for less than $10. By combing the board and a USB breakout PCB inside of a 3D printed case, you’ve got a plug-and-play WiFi adapter that the TiVo thinks is the real deal.

There was a time when Hackaday was flooded with TiVo hacks, but it’s now been more than a decade since cheap carrier-provided DVRs ate the company’s lunch. Realistically, there’s an excellent chance that this post will be the only time a mention of the once-mighty DVR graces the front page in 2020. While the reign of the TiVo might be at its end, the impact it had as one of the first Linux-powered consumer devices will be etched in hacker history forever.

Designing And Building A Custom Optical Fuel Sensor

October 14, 2020 by Tom Nardi 36 Comments

At some time or another, we’ve all had an idea we thought was so clever that we jumped on the Internet to see if somebody else had already come up with it. Most of the time, they have. But on the off chance that you can’t find any signs of it online, you’re left with basically two possible conclusions. Either you’re about to enter uncharted territory, or your idea is so bad that everyone has collectively dismissed it already.

Which is precisely where [James Stanley] recently found himself. He had an idea for an non-contact optical sensor which would detect when his racing mower was about to run out of gas by analyzing light passed through a clear section of fuel hose. He couldn’t find any previous DIY examples of such a device, nor did there appear to be a commercial version. But did that mean it wouldn’t work, or that nobody had ever tried before?

Continue reading “Designing And Building A Custom Optical Fuel Sensor” →

The Amazing Technicolor Parts Organizer

October 3, 2020 by Tom Nardi 9 Comments

It wouldn’t be much of an exaggeration to say that anyone reading these words has struggled at one time or another to keep an ever growing collection of electronic bits and bobs from descending into absolute chaos. Tossing them all into plastic bins is at least a start down the road to long-term organization, but they still needed to be sorted and inventoried if you want to avoid the wasted time and money of buying parts you forgot you already had.

For his latest project, [Zack Freedman] decided to finally tackle the personal parts collection that he’s ended up lugging around for the last several years. The first half of the battle was just figuring out what he actually had, what he was likely to need down the line, and getting it all sorted out so he didn’t have to keep rummaging through a big pile to find what he needed. But it’s not enough to get organized, you also need to stay organized.

Which is why he then turned his attention to how all these newly sorted components would actually be stored going forward. He already had a trio of Harbor Freight bin organizers, but as one expects from that fine retailer, they were only marginally suitable for the task at hand. So [Zack] designed a 3D printed faceplate that could snap onto the original plastic bin. The new fronts made them easier to grab and featured an opening to accept a laser-etched plastic label.

To give them a little visual flair, he decided to print the faceplates using rainbow gradient filament. To prevent them from being random colors, he used the relatively obscure sequential slicing option so his Prusa i3 would print each faceplate in its entirety before moving over to the next one on the bed. This took far longer than doing them in parallel (especially since he had access to multiple printers), but makes for a much nicer aesthetic as the color smoothly transitions between each bin on the wall. It also has a practical benefit, as you can tell at a glance if any of the bins have found themselves in the wrong spot.

If you really want to go off the deep end, we’ve seen hackers light individual bins with RGB LEDs tied into a searchable inventory system. But for most hobbyists, simply learning when to purge would be more practical.

Continue reading “The Amazing Technicolor Parts Organizer” →

Building A USB-C Charger For Canon NB-4L Batteries

September 23, 2020 by Tom Nardi 17 Comments

One of the most appealing aspects of USB-C is that it promises to be a unified power delivery system. You’ll no longer need to have a separate power cords for for your phone, camera, and laptop; physically they’ll all use USB-C connectors, and the circuitry in the charger will know how much juice to send down the line for each gadget. But in reality, we’ve all got at least a few pieces of older equipment that we’re not about to toss in the trash just because it doesn’t support the latest USB spec.

Case in point, the old Canon camera that [Purkkaviritys] modified to take infrared pictures. Instead of abandoning it, he decided to make a custom USB-C charger for its NB-4L batteries. Since they’re just single cell 3.7 V lithium-ions, all he had to do was wire them up to the ubiquitous TP4056 charger module and design a 3D printed case to hold everything together.

He did go the extra mile and replace the SMD charging indicator LEDs on the PCB with 5 mm LEDs embedded into the 3D printed enclosure, though you could certainly skip this step if you were in a hurry. We imagine if you print the enclosure in a light enough color, you should be able to see the original LEDs glowing through the plastic.

This project is yet another example of how incredibly useful the TP4056 module really is. If there’s even a chance you might want to build a rechargeable gadget in the near future, you should have a few of these cheap boards ready to go in the parts bin.