very short time for execution

trazym

Hi,
i'm new on this forum, i'm new in electronic design and i'm french so my english is poor!!

I want to built an electronic controle device for my 2 stroke motorbike. This engine may turn up to 12000 rev/sec and the cycle period is reduced to 5msec.
To control the engine and to ensure a good timing i need to do about 15 basics operations like "+", "-", comparison,... in 50µsec. Is it possible with the Basic stamp 2 module? If not, can you help me to chose the right microcontroller?

Thank you for your answers!!

Mike Green

The Basic Stamp 2 module executes perhaps 4000 instructions per second. That's not fast enough for what you want to do.

The Propeller would be a good choice for this. It is certainly fast enough. In the Spin language which is interpreted, the basic operations take maybe 2us. The actual native instructions take 50ns and there are 8 separate independent processors on the chip. Someone else made a very nice motorcycle control console, but I can't find the links to it. You could try browsing through the Completed Projects forum a year or so back in time.

W9GFO

Holy cow! 12,000 rev/sec!!!! That's 720,000 rpm!! Not even gas turbines turn anywhere near that fast!

12,000 rpm would be 200 revs/sec. You're looking at 5 ms per revolution.

The BS2sx does 10,000 instruction/sec and the BS2px does 19,000. Wouldn't one of those be fast enough?

Rich H

Post Edited (W9GFO) : 3/27/2009 2:27:37 PM GMT

trazym

Thank you for your answers!!

Of course it is 12000rev/min (oups) and a 5ms period but during this 5ms the engine does a whole rotation (360°) and controlling ignition needs to calculate timing point during a few degrees (less than 5) so we're near the 0,07ms for about 15 instructions... (about 5µs each)

As i'm a beginner i wanna by a complete kit such as:

http://www.parallax.com/Store/Microcontrollers/PropellerProgrammingKits/tabid/144/CategoryID/20/List/0/SortField/0/catpageindex/1/Level/a/ProductID/415/Default.aspx
http://www.parallax.com/Store/Microcontrollers/PropellerProgrammingKits/tabid/144/CategoryID/20/List/0/SortField/0/catpageindex/1/Level/a/ProductID/382/Default.aspx

Which one would you chose?

Regards

Fred

Mike Green

The Propeller Education Kit would be more useful for learning purposes. There's a growing set of tutorials and exercises designed for it. The Demo Board kit is easier to deal with if your main interest is the programming since it has already wired interfaces for video, audio, a keyboard and a mouse. I would probably get the PropStick version of the Propeller Education Kit (www.parallax.com/Store/Microcontrollers/PropellerProgrammingKits/tabid/144/ProductID/506/List/1/Default.aspx?SortField=ProductName,ProductName) since that uses a Propeller module with a voltage regulator / EEPROM / processor chip / crystal already wired together. It's less work to get started and less work to transfer the Propeller to a permanent board when you're ready.

trazym

Ok thank you for your help!
I've bought the propstick education kit. I wish it will be here as soon as possible!
You may have some news about me on the propeller forum...