Frankenstein, The Open Source Engine Control Unit

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The Engine Control Unit is a vital part of every car made in the last 40 years or so, but unlike just about every other electronic device, open source solutions just don’t exist. [Andrey] is trying to change that with rusEfi, a project that hopes to bring together hardware, software, and engines in one easy to use package. He’s even designed Frankenstein, a full ECU ‘shield’ for the STM32F4 Discovery dev board.

This isn’t the first time we’ve seen [Andrey]‘s adventures in building an ECU. An earlier board was also powered by the STM32F4 Discovery, and he actually drove his 96 Ford Aspire around using this homebrew ECU. It was only firing on two cylinders, but that was only a loose solder connection.

Of course building an ECU from scratch is worthless without the proper firmware that balances and engine’s fuel economy and performance. This sort of testing must be done empirically and [Andrey] has a Kickstarter going for the development of this firmware and some dyno time. No rewards, but it’s worth chipping in a buck or two. I did.

Videos below.

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Homebrew Phase Laser Rangefinder

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Just when you thought ARM micros couldn’t get any cooler, another project comes along to blow you away. [Ilia] created a phase laser rangefinder (.ru, Google translatitron) using nothing but a laser diode, a pair of magnifying glasses, a few components and an STM32F4 Discovery dev board.

The theory behind this build is using a laser’s phase to determine how far away an object is. By modulating the laser diode’s output at a few hundred Mhz, the reflection from the laser can be compared, giving a fairly reasonable estimate of how far away the target is. This method has a few drawbacks; once the reflection is more than 360 degrees out of phase, the distance ‘loops around’ to being right in front of the detector.

The laser diode used does not have any modulation, of course, but by using an STM32F4 ARM chip, [Ilia]was able to modulate the amplitude of the laser with the help of a driver board hacked out of a 74HC04 chip and a few resistors. Not ideal, but it works.

The receiver for the unit uses a photodiode feeding into the same microcontroller. With an impressive amount of DMA and PLL wizardry (the STM32F4 is really cool, you know), the phase of both the transmission and reflection can be compared, giving a distance measurement.

It’s all an impressive amount of work with a hacked together set of optics, a cheap dev board, and a few components just lying around. For any sort of application in a robot or sensor suite this project would fall apart. As a demonstration of the theory of phase laser rangefinding, though, its top notch.

You can check out a video of [Ilia]‘s rangefinder below. Be sure to full screen it and check out the distance measurement on the LCD. It’s pretty impressive.

Thanks [Володимир] for the link.

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STM32 Nucleo, The Mbed-Enabled, Arduino-Compatable Board

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The STM32 line of microcontrollers – usually seen in the form of an ST Discovery dev board – are amazingly powerful and very popular micros seen in projects with some very hefty processing and memory requirements. Now, ST has released a great way to try out the STM32 line with the Nucleo board.

There are two really great features about these new Nucleo boards. First, they’re mbed compatable, making them a great way to get started in the ARM development world. Secondly, they have Arduino pin headers right on the board, giving you access to all your shields right out of the box.

Right now, there are four varieties of the Nucleo board based on the STM32F030, -F103, -F152, and -F401 microcontrollers. The STM32F401 is the high-powered variant, An ARM Cortex-M4 microcontroller running at 84 MHz, 512kB of Flash, and enough I/O for just about any project.

If you’d like to get your hands on one of the STM32 Nucleo boards, you can order a voucher to pick one up at Embedded World in Germany next week. Otherwise, you’re stuck ordering from Mouser or Farnell. Bonus: the high-end F401-based board is only $10 USD.

OpenMV: The Camera For Your Next Project

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Last month we saw [Ibrahim] tackle the lack of cheap, high speed, high resolution serial cameras with full force. He designed a serial camera based on the STM32F4 microcontroller that’s the perfect solution to anyone wanting to add visual processing or machine vision to a project. It’s cheap, too: instead of the $100 or so you’d spend on a high-end serial camera, [Ibrahim]‘s version only has about $15 in parts.

Now he’s back at it again, with 25 FPS face detection, 30 FPS color detection, a new board with a micro SD socket, and support for USB OTG full speed. [Ibrahim] has been hard at work deep in the bowels of the STM32F4 micro, playing around with the core coupled memory. This allows for some very fast image processing, combined with the micro running at 168 MHz makes for very fast face and color detection.

As for a few benchmarks for this camera, the maximum resolution is 1280×1024, and at 88×72 resolution this little board can output at 60 FPS. Of course everything is limited by the speed of the serial connection, but there’s a lot of potential in this small serial camera.

No word on how much this board will cost, but [Ibrahim] may be putting a few boards up on Tindie shortly. Here’s to hoping he’ll send us an email telling us when his store is open.

Breadboard Friendly ARM Board Based on STM32F4

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Umm yeah… this is more like it. The STM32F4Stamp is a project which [Frank Zhao] put together to make his ARM prototyping process more like is was back when everything came in a DIP format. As you can see, it’s just narrow enough to leave one row open on the breadboard for jumper wires.

Don’t get us wrong, we do really like STM’s own Discovery Boards for the hardware they deliver at a very low price. But the dual-row pin headers on the larger versions (all except the F0 variant) make it tricky to connect your peripherals. This is pushed to the point that a large percentage of hacks we’ve seen with the Discovery boards are actually just to make connecting external hardware easier.

You may be thinking that there’s a lot missing from this board, but we disagree. Obviously there’s still a USB port which can be used to power the board via a 3.3V regulator. But since the STM32 chips have a built-in bootloader the USB connection can also be used to flash firmware to the processor. Nice! It’s open hardware if you want roll your own. For your convenience we’ve embedded the schematic after the break, along with [Frank's] demo video.

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UDP between STM32-F4 Discovery boards

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[The Backwoods Engineer] tested out a new accessory kit for the STM32-F4 Discovery board. The image above shows two boards communicating with the UDP protocol. Notice the extra PCB into which each Discovery board has been plugged. This is a third-party add-on which adds Ethernet, RS-232, SD card slot, and a connector for LCD or Camera. We’ve had one of these F4 Discovery boards on hand for a while and haven’t figured out a good way to connect external hardware to the huge dual pin-headers. This doesn’t solve the problem — the base board also includes dual headers to break-out all the pins — but having Ethernet, serial, and SD certainly reduces the need to add all that much more. The other drawback to the hardware is that the sample firmware is targeted at the IAR Embedded Workbench which is neither free, nor in the realm of affordable for hobbyists.

The NIC used on the baseboard has auto-crossover capabilities so the boards were connected using a regular Cat6 patch cable. This example has the boards constantly sending UDP packets with the module on the right reporting status information to a terminal via the serial connection.

A guide and helper script for ARM cross compiling toolchain on a Mac

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[Mitchell Johnson] wanted to develop for the STM32F4 Discovery board on his Mac. There are a few ready-to-use options when it comes to the ARM toolchains, but he couldn’t find one that satisfied all of his needs. After working out all the kinks he wrote a guide and tweaked a script to install the ARM tools on a Mac.

The problem he had with some of the pre-packaged tool chains is that they didn’t support the hardware floating point functionality of STM’s Cortex-M4 chips. To get around this without doing his own ground-up build (which can be quite a challenge) he forked the Summon Arm Toolchain script and modified it to include ST-Link support in the build. One of the things that we like about that script is it installs the tools in a sub-directory of your home directory. This way if you already have another ARM toolchain you can switch between the two by tweaking your PATH variable.