RE: Ultrasonic Reversing Monitor

twenty9 — Sat, 06 Feb 2016 10:01:06 GMT

You asked about safety and gave an gave some interesting and easy-to-understand answers.

I am a software engineer in automotive industry for a big German company.

15 years ago our software fit into a 16-bit microcontroller (clocked at 16 MHz) with 32 kB of FLASH. Nowadays we use 32 bit microcontrollers with clock speed of 120 MHz and up to 3 MB of FLASH. Although there are a few improvements, the main functionality - i.e. what the driver of a car with our system really sees - is basically the same.

What was the cause for this increase of codesize and performance needs?

1) Standards: First, the car manufactures required standardized (and increased) communication protocols, which only become active when your car is in repair-shop, then they requested an OSEK-operating system, (which really nobody sees). Nowadays AUTOSAR is a standard, which specifies operating system, standard layers of drivers in basic software, and the communication between software components.

2) Safety: IEC 61508 'Functional Safety of Electrical/Electronic/Programmable Electronic Safety-related Systems' and its more automotive-specific successor ISO 26262 'Road vehicles – Functional safety' specify, what you have to consider, when you develop electronic systems, which might lead to accidents, injuries or death when something breaks does not work as intended.

Example: One cell of FLASH-memory looses its contents (some electrons diffuse faster as expected). This might lead to a pointer to a wrong address. So the part of software, which normally supervises some temperature sensor, writes in a variable, which causes full-throttle. Think what might happen, if your car accelerates on its own without any reason in any driving situation...

Solution: You have to execute a checksum check on the contents of your FLASH-memory. But what happens, if the checksum check itself is influenced by the corrupted memory contents?

I am not against standards and safety. But it costs...

And sometimes people forget to think on their own. (I very much like the sign "This machine has no brain - use your own")

And all the safety-concerns restrain progress. Let's say you want to really sell your "Ultrasonic Reversing Monitor". Then you have to think about all the safety stuff. Even when you install it for free in your neighor's garage, he might no longer be your friend after he has crashed his car...

In my garage I use a golf-ball which is hanging from the roof. When it touches the car, I have to stop.

RE: Ultrasonic Reversing Monitor

DAB — Thu, 07 Jan 2016 20:03:10 GMT

Nice update.

Where did you take the picture of all the traffic lights?

It looks guaranteed to confuse the drivers and maximize accidents.

DAB