Muncher

Hi John,

I don't know which microcontroller you are using but you may be able to find a similar model with the same instruction set but a greater EEPROM capactity.

I had a similar problem with an 8051 controller that only had 256 bytes of ram onboard (no external memory), I found a different variation that expanded this to 1024 bytes for a similar cost. Saved me losing a load of I/O pins to have external memory wired in.

Giles.

brickboy

John, would it be simplified by assuming a 100% closed duty cycle (i.e. wasetgate actuator sees no pressure at all) until, say, 2500rpm, then modulate from there upward? It would mean an RPM-driven cycle could be implemented over a narrower range.

Also, I guess it should be at 100% open duty cycle from 5500rpm upward, on the assumption that at these revs it's going to be pretty much on max boost?

john banks

Have posted new thread to get new attention to the problem.

I have a good system to control boost which works very well on part throttle and is very responsive in all gears.

However, you just set one boost target and one base duty cycle for the whole rev range, and I want more finesse to be able to adjust boost by RPM.

I don't want the design to get overcomplicated though.

I think I need boost targets and approximately correct duty cycles at about 400rpm increments across the range. I have been trying to think of a self learning mode as to how to set this all up. I suppose it only has to be done once, but I want to minimise the need for keyboards and displays on my design.

Any ideas welcome - you don't need to be an electronics or computer whizz to contribute. The microcontoller has 256 bytes of EEPROM, but I am running out of SRAM space for more variables.

Also some boost controllers are fitted and then just adjuted with a single **** - eg the MRT TMS 1,2,3 and seem to work OK. The HKS EVC I know goes through a self learning mode.

How do I keep it simple to dial in your desired boost - do I set sensible values for PID contants and work out some duty cycles for different boost levels?

The battle is keeping it simple but functional and easy to set up but effective.

The AVC-R apparently works well but is rumoured to be a pig to set up and need duty cycles and boost targets plugged in across the rev range.

I thought about a self learning mode where you go through the revs in 3rd gear at a few different fixed duty cycles - this creating a map of duty cycles that could then be used help the boost target system work more smoothly.

[Edited by john banks - 2/11/2002 10:13:30 AM]