Hacking A Thermal Imager For Dual-use Of The Thermal Sensor

Sometimes a device doesn’t do quite what one needs, and in those cases a bit of tampering might do the trick. That’s what led to being able to record video from a HTI HT-A1 thermal imager despite the device not actually supporting that function, thanks to careful investigation and warranty violation.

Plugging in a custom USB cable allows a mobile phone app to access the thermal sensor, while the host device itself remains ignorant.

We’ve seen a teardown of the HT-A1 in the past, and it turns out that Seek — the manufacturer for the actual thermal sensor inside the device — released an OEM development kit and mobile phone app for their modules. Could this mean that the raw sensor module in the HT-A1 could be accessed via the developer kit app? One hacked together USB cable later showed that the answer is yes! Not only does the app allow viewing thermal imagery, but it makes it possible to do things like record video (a function the HT-A1 itself does not support.)

But even if the HT-A1 doesn’t allow recording, as a handheld thermal sensor with a screen it’s still pretty useful in its own way and it would be shame to gut the unit just for a raw sensor module. The best solution ended up being to put the sensor back into the HT-A1, and install some switching circuitry to disconnect the sensor from the HT-A1’s CPU and divert its data to the USB plug on demand. This means the HT-A1 can be used normally, but by plugging in a custom-made cable while the unit is off, the thermal sensor can be accessed by the mobile phone app instead. Best of both worlds. You can see a brief celebratory thermal cat video embedded below, proving it works.

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DIY Thermal Imager Uses DIY Gaussian Blur

Under the right circumstances, Gaussian blurring can make an image seem more clearly defined. [DZL] demonstrates exactly this with a lightweight and compact Gaussian interpolation routine to make the low-resolution thermal sensor data display much better on a small OLED.

[DZL] used an MLX90640 sensor to create a DIY thermal imager with a small OLED display, but since the sensor is relatively low-resolution at 32×24, displaying the data directly looks awfully blocky. Gaussian interpolation to improve the display looks really good, but it turns out that the full Gaussian interpolation isn’t a trivial calculation write on your own. Since [DZL] wanted to implement it on a microcontroller, the lightweight implementation was born. The project page walks through the details of Gaussian interpolation and how some effective shortcuts were made, so be sure to give it a look.

The MLX90640 sensor also makes an appearance in the Open Thermal Camera, one of the entries for the 2019 Hackaday Prize. If you’re interested in thermal imaging, don’t miss this teardown of a thermal imaging camera.

DIY thermal imaging heat map

DIY Thermal Imaging Done Low-Tech Style

[Niklas Roy] has always wanted to try out thermal imaging and saw his opportunity when he received one of those handheld IR thermometers as a gift. But not content with just pointing it at different spots and looking at the temperatures on the LCD display, he decided to use it as the basis for a scanning, thermal imaging system that would display a heat map of a chosen location on his laptop.

DIY thermal imaging system
DIY thermal imaging system

He still wanted to to be able to use the IR thermometer as normal at a later date so cutting it open was not an option. Instead he firmly mounted a webcam to it pointing at the LCD display. He then wrote software on his laptop to process the resulting image and figure out what temperature was being displayed.

Once he got that working, he next put the thermometer on a platform with servos connected to an Arduino for slowly rotating it in the horizontal and vertical directions, also under control of the software on his laptop. Each time the thermometer measures the temperature of a spot, the software decodes the temperature on the LCD display and then tells the Arduino to use the servos to point the thermometer at the next spot to be measured. Each measurement takes a little time, so scanning an entire location as 70×44 spots takes around a half hour. But the end result is a heat map drawn on the laptop, done by a device that is low-tech. [Editor’s Snark: Because attaching a webcam and processing the images is “low-tech” these days.] He can overlay the heat map on a normal photo to see at a glance where the hot spots are.

The software he wrote is available on GitHub and the video below shows it in action. We’ve got to admit, it’s pretty awesome to watch. You can even see the heat map being filled in one measurement at a time.

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Hackaday Links: August 30, 2014


Adafruit did another Circuit Playground, this time concerning frequency. If you’re reading this, no, it’s probably not for you, which is great because it’s not meant to be. If you have some kids, though, it’s great. Not-muppet robots and oscilloscopes. Just great.

The Hack42 space in Arnhem, Neterhlands recently got an offer: clean out a basement filled with old computer equipment, and it’s yours. Everything in the haul had to fit through an 80cm square door, and there are some very heavy, very rare pieces of equipment here. It’ll be a great (and massive) addition to their museum. There’s a few pics from the cleanout here and here.

[Mike] has been working on a project to convert gerber files into SVGs and it’s great.

[Carl] did a roundup of all the currently available software defined radios available. It’s more than just the RTL-SDR, HackRF, and BladeRF, and there’s also a list of modifications and ones targeted explicitly to the ham crowd.

This is a Facebook video, but it is pretty cool. It’s a DIY well pump made in Mexico. A few rubber disks made out of an old inner tube, a bit of PVC pipe, and a string is all you need to bring water to ground level.

What can you do with a cellphone equipped with a thermal imaging camera? Steal PIN codes, of course. Cue the rest of the blogosphere sensationalizing this to kingdom come. Oh, what’s that? Only Gizmodo took the bait?

About a year ago, we saw a pretty cool board made by [Derek] to listen in on the CAN bus in his Mazda 3. Now it’s a Kickstarter, and a pretty good one at that.

Your connectors will never be this cool. This is a teardown of a mind bogglingly expensive cable assembly, and this thing is amazing. Modular connectors, machined copper shields, machined plastic stress relief, and entire PCBs dedicated to two caps. Does anyone know what this mated to and what the list price was?