STM32F

2 Articles

A Nano With An Otter’s Bite

February 1, 2020 by 22 Comments

The would-be microcontroller experimenter is now faced with a bewildering array of choices when it comes to a tiny development board for their projects. Everything from descendants and clones of the original Arduino through to full-fat Linux powerhouses such as the Raspberry Pi Zero and similar boards can be had, and often for a reasonable price.

A new entrant has now joined the fray, the OtterPill is an STM32F072-based board with an Arduino-Nano-like pinout, and it comes from the bench of [Jana Marie]. With so many competitors you might ask yourself what it can offer, and it would be a valid point given that a Nano clone can be had for relative pennies. Aside from the Nano shield compatibility and extra power of the ARM Cortex M0 then, it’s an open source development board with USB-PD included from its USB-C socket, and with some elite BoM wizardry she’s managed to get the cost of its components to below three dollars. A USB-PD example firmware is available and a blank firmware is on its way. For now the board exists only in prototype form, but she’s putting together a production run if you would like one too. We saw an early development of it at eth0 back in the autumn, and given the progress since then we’re sure that we won’t have to wait for long.

Regular readers will recognise [Jana Marie]’s work, because otter-themed boards have made their way to these pages before. Our most recent ones were the USB-C replacement board bringing USB-PD to the TS-100 soldering iron, and  a nifty little USB board for addressable LEDs.

Dashboard Dongle Teardown Reveals Hardware Needed To Bust Miles

December 16, 2019 by 43 Comments

Progress and the proliferation of computers in automotive applications have almost made the shade tree mechanic a relic of the past. Few people brave the engine compartment of any car made after 1999 or so, and fewer still dive into the space behind the dashboard. More’s the pity, because someone may be trying to turn back the odometer with one of these nefarious controller area network (CAN bus) dongles.

Sold through the usual outlets and marketed as “CAN bus filters,” [Big Clive] got a hold of one removed from a 2015 Mercedes E-Class sedan, where a mechanic had found it installed between the instrument cluster and the OEM wiring harness. When the dongle was removed, the odometer instantly added 40,000 kilometers to its total, betraying someone’s dishonesty.

[Big Clive]’s subsequent teardown of the unit showed that remarkably little is needed to spoof a CAN bus odometer. The board has little more than an STM32F microcontroller, a pair of CAN bus transceiver chips, and some support circuitry like voltage regulators. Attached to a wiring harness that passes through most of the lines from the instrument cluster unmolested while picking off the CAN bus lines, the device can trick the dashboard display into showing whatever number it wants. The really interesting bit would be the code, into which [Clive] does not delve. That’s a pity, but as he points out, it’s likely the designers set the lock bit on the microcontroller to cover their tracks. There’s no honor among thieves.

We found this plunge into the dark recesses of the automotive world fascinating, and [Big Clive]’s tutelage top-notch as always. If you need to get up to speed on CAN bus basics, check out [Eric Evenchick]’s series on automotive network hacking.

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