Embed with Elliot: Microcontroller Makefiles

Last time on Embed with Elliot, I began my celebration of the make command’s 40th birthday next month. We discussed using the default rules and how to augment them with your own variables defined in a makefile. Next, I’ll walk you through some makefiles that can be used for real-world microcontroller code development. This week, we’ll focus on one for the AVR platform, and later on, I’ll run through a slightly more complicated version for the ST32M series of ARM Cortex micros.

Along the way, we’ll pick up a couple of tricks, but the aim is to keep the makefiles minimal, readable, and easily extensible. Once you get a little taste of the power of writing your own makefiles, you probably won’t be able to stop adding bells and whistles — custom routines for flashing, checking the size of binaries, generating assembly listings, etc. I’ll leave the extras up to you, but you’ll eventually find that anything you do can be automated with a makefile.

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Embed With Elliot: March Makefile Madness

The make tool turns the big 4-0 next month, and we thought we’d start up the festivities early. In a two-part series, I’ll cover some of the make background that I think is particularly useful, and then focus on microcontroller-specific applications. If you’re still cut-and-pasting a general purpose makefile to run your toolchain, hopefully you’ll get enough insight here to start rolling your own. It can be a lot simpler than it appears!

Just as soon as the C programming language was invented, and projects started to get a little bit bigger than a “hello world”, it became obvious that some tool was needed to organize and automate compilation. After all, if you’ve got a program that’s spread over a number of files, modules, or libraries, it’s a hassle to have to re-compile them all any time you make a change to just a single section of code. If some parts haven’t changed, you’re just wasting time by re-compiling them. But who can keep track of all of this? Make can!

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Mad Max Inspired Flamethrower Ukulele

The new Mad Max movie is getting a lot of buzz, and a few people are calling it a modern classic. There’s a flamethrower guitar in the movie, which means it’s time for cosplay accouterments. Our ‘ol buddy [Caleb] loves flamethrowers and poofers, so hacking together a Doof Warrior inspired flamethrowing ukulele was natural for him.

The fuel for this uke is a can of butane actuated with a caulking gun. This setup is actually pretty clever; by removing the locking tab on the caulking gun, butane is released when the gun’s trigger is squeezed, but stops when the trigger is released. The igniter is a simple grill igniter is used to light the gas.

[Caleb] is rather famous for his flamethrowing creations. His life-size fire-breathing piranha plant uses a similar setup to shoot fire.

Video below.

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Hackaday Reader [David] Wins a Camera from Make and Nikon


Make the shot fixed[David Schwarz] whipped up this moving time-lapse camera rig and won himself a sweet Nikon setup. You might remember our post about the Nikon Make:The Shot Challenge. [David] saw our post, and started thinking about what he wanted to enter. Like a true engineer, he finally came up with his idea with just 3 days left in the contest.

[David] wanted to build a moving time-lapse rig, but he didn’t have the aluminum extrusion rails typically used to build one. He did have some strong rope though, as well as a beefy DC motor with a built-in encoder. [David] mounted a very wide gear on the shaft of the motor, then looped the rope around the gear and two idler pulleys to ensure the gear would have a good bite on the rope. The motor is controlled by an Arduino, which also monitors the encoder to make sure the carriage doesn’t move too far between shots.

[6__pulley_systemDavid] built and tested his rig over a weekend. On Monday morning, he gave the rig its first run. The video came out pretty good, but he knew he could get a better shot. That’s when Murphy struck. The motor and controller on his rig decided to give up the ghost. With the contest deadline less than 24 hours away, [David] burned the midnight oil and replaced his motor and controller.

Tuesday morning, [David] pulled out his trump card – a trip to Tally Lake in Montana, USA. The equipment worked perfectly, and nature was cooperating too. The trees, lake, and the shadows on the mountains in the background made for an incredible shot. Once the time-lapse photos were in the can, [David] rushed home, stitched and stabilized the resulting video. He submitted his winning entry with just 2 hours to spare.

Click past the break for more on [David’s] time-lapse rig, and to see his final video.

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Hack a Camera, Win a Nikon


Several juicy prizes from Nikon are ripe for the plucking. Our friends at MAKE are hosting a Nikon sponsored challenge. Grand prize is an Nikon 1 V3 with three extra lenses, and there are two runner-up prizes which offer the same without the extras. They’re basically asking for your best camera hack. Now the submission process is a one-shot deal (no posting and iterating) which may explain why the contest — which started 4/15 and ends 5/13 — only has two entries. Still, we’d love to see a Hackaday reader waltz in and claim the loot.

Need some examples to get you rolling? Connectivity is a fun topic; try interfacing your camera with something like a Nintendo DS. Everyone needs to make at least one motion rig like this Ikea slider. We can’t stop listing examples without at least one shutter trigger. Here’s a sound activated one to capture things that happen extremely quickly.

If you end up winning make sure to tell us so we can share in your delight.

Bass Bump Headphone Amp


Headphone amplifiers make for simple, practical electronics projects. The Bass Bump Headphone Amp is no exception, since it’s made out of easy to source parts, and can be built on a proto-board.

We’ve seen many variants of the classic cMoy amplifier, including this pretty one. The Bass Bump differs by providing control over bass frequencies. It does this by putting a filter in front of the amplifier, with a potentiometer to select the mix of frequencies. This goes into a LM386 audio amplifier. At the output is a Zobel network to keep the impedance low at high frequencies. The amplifier can be powered from either a 9V rechargeable battery, or a USB port.

It’s a simple build, but definitely a good one to try on a rainy day. The write up explains how the analog circuitry works, and gives you full instructions on how to build it. After the break, check out a video overview of the project.

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Musical Pencil Synthesizer


Here’s another fun weekend project for the hacker younglings, a musical synthesizer that plays different musical tones based on the resistance of your conductive graphite drawing!

Like our recent post on a DIY Metal Detector, this project makes use of the ever relevant 555 timer. Except in this case they are using a more modern TLC555 timer which only requires 3V instead of the typical 4.5V. It’s a fairly simple project that you should be able to complete in just a few hours.

The circuit is quite basic. The 555 timer outputs in astable mode, which means there is a continuous stream of pulses from pin 3 which go right into the speaker circuit. The rest of the circuit monitors the resistance of whatever the pencil is touching, including you! Changes in resistance result in the variation of pulses outputted by the 555 timer.

As always, the video guide is after the break.

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