Ask Hackaday: Dude, Where’s My MOSFET?

(Bipolar Junction) Transistors versus MOSFETs: both have their obvious niches. FETs are great for relatively high power applications because they have such a low on-resistance, but transistors are often easier to drive from low voltage microcontrollers because all they require is a current. It’s uncanny, though, how often we find ourselves in the middle between these extremes. What we’d really love is a part that has the virtues of both.

The ask in today’s Ask Hackaday is for your favorite part that fills a particular gap: a MOSFET device that’s able to move a handful of amps of low-voltage current without losing too much to heat, that is still drivable from a 3.3 V microcontroller, with bonus points for PWM ability at a frequency above human hearing. Imagine driving a moderately robust small DC robot motor forwards with a microcontroller, all running on a LiPo — a simple application that doesn’t need a full motor driver IC, but requires a high-efficiency, moderate current, and low-voltage-logic compatible transistor. If you’ve been here and done that, what did you use?

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Pioneer AVIC Infotainment Units Hacked To Load Custom ROMs

Pioneer’s flagship AVIC line of in-car multimedia systems is compatible with both Android Auto and Apple Car Play, and offers all manner of multimedia features to the driver of today. What’s more, these in-dash wonders have spawned their own community, dedicated to hacking the units. The ultimate infotainment hack is to develop custom ROMs for these devices.

What this means is that owners of Pioneer AVIC units will eventually be able to flash a custom ROM onto their in-car device, allowing it to operate more like any other generic Android tablet on the market. The potential is there for installing custom applications, extra hardware (such as OBD II readers), or pretty much anything else you can do with an Android device.

The hack involves a whole lot of delicate steps, beginning with using a USB stick with a special image to boot the device into a test mode. This allows the internal SD card to be backed up, then overwritten with a new image itself.

Mostly, the hack has been used to allow map files to be updated on the internal SD card — inability to update maps has been a long festering thorn in the side of in-dash navigation systems. Users have been customizing this to suit their requirements, also adding speed camera locations and other features. But overall this hack is a great example of hacking something to get full control over the things you own. At the least, this will allow drivers to ditch the phones suction-cupped to the windshield and run common apps like Waze, Uber, and Lyft directly on the infotainment screen (assuming you can rig up an Internet connection).

Check out another great Android ROM hack — using a cheap old smartphone as a low-cost ARM platform.

Be Your Own Google Mapper

Google Maps is one of the modern wonders of the world. It is hard to remember how expensive it used to be to get high-quality aerial  images. Of course, you don’t get to pick when they fly over a particular piece of the planet. If you are like [Dennis Baldwin] that’s not good enough. He’s been using his drone to document the construction of a high school stadium.

[Dennis] uses the open-source GDAL tools to create Google Map tiles from drone imagery. Even better, he’s documented the process in the video you can find below. Once you can make your own map tiles, you can control when you take the images — important if you are documenting construction like [Dennis] did.

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