The MegaSquirt Project has experienced explosive growth other the years, with hundreds of new MS installations occurring every week - a phenomenal success! MegaSquirt has been successfully used in all aspects of Internal Combustion engine applications including R&D, Industry, Race, and Research. The MS project has transformed itself from a simple R&D project into a full-featured mature engine control system. To reflect this the support structure has also changed to meet the needs of MegaSquirt Users.
Moving forward, the R&D forums for MegaSquirt project are in a read-only mode - no new forum posts are accepted.
However the forums will remain available for view, they still contain a wealth of information on how MegaSquirt works, how it is installed and used. Feel free to search the forums for information, facts, and overview.While the R&D forum traffic has slowed in recent years, this is not at all a reflection of Megasquirt users, which continue to grow year after year. What has changed is that the method of MegaSquirt support today has rapidly moved to Facebook, this is where the vast majority of interaction is happening now. For those not on Facebook the msextra forums is another place for product support. Finally, for product selection assistance, all of the MegaSquirt vendors are there to help you select a system, along with all of the required pieces to make it complete.
This forum is for discussion of MicroSquirt (TM) from Bowling and Grippo. The MicroSquirt information site is at www.usEasyDocs.com
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Read the manual to see if your question is answered there before posting. If you have questions about MS1/Extra or MS2/Extra or other non-B&G code configuration or tuning, please post them at http://www.msextra.com The full forum rules are here: Forum Rules, be sure to read them all regularly.
Hi,
First post here on the MS forum. I have been looking for a way to build a turbo controller and I'm thinking that use of a MS ECU is the way to do it. The reason why I want to consider the MS is because I want my turbo control to be a function of RPM and intake manifold pressure. The device I am trying to control is an electronic actuator from a variable geometry turbo. The actuator requires a PWM control signal at 250Hz frequency, and the duty range is from 20% to 80%. So, my desire is to map this duty cycle as a function of engine speed and boost pressure. This brings me to my question... If I was to buy a bare-bones MS and only one sensor (for rpm), is it possible to generate a mapped PWM output? I have been studying this website and I am wondering if this can either be done with the injector output signal or by using the CAN-based GPIO board. Keep in mind I don't nned to control a whole engine, I'm just trying to turn a RPM and MAP signal into a mapped PWM output at 250Hz frequency. Any advice will be appreciated.
Thanks,
Brock
The hardware is more capable of doing what you decribe. However, I think for the amount of effort to configure the MS to function how you wish, you could easily use any number of other hardware solutions that would be both cheaper, more compact, and more directly suited to your goals.
Also, how much draw does the actuator have?
A rather simple Micro PIC would be more than capable of handling the software end of it, and a fairly simple proto-board circuit would drive it. I'm not sure how little timing accuracy or resolution you could get away with however.
I'm most familiar with PICAXE chips, which are basicly a PIC chip with a bootloader to be able to serially load the software. But I'm not sure if there is enough intuitivity in the PICAXE Basic interpreter to handle the mapping required for you application. But there are definatlely lots of options you can look into.
Could the MSnS-Extra Boost Controller feature be suitable for your app with a tweak to 250Hz? It's intended to change DC based on rpm & kPa, though only interpolated 4/4 at this moment. http://megasquirt.sourceforge.net/extra/boost.html
May I ask what your requirement is for variable mapped boost?
PSIG wrote:Could the MSnS-Extra Boost Controller feature be suitable for your app with a tweak to 250Hz? It's intended to change DC based on rpm & kPa, though only interpolated 4/4 at this moment. http://megasquirt.sourceforge.net/extra/boost.html
May I ask what your requirement is for variable mapped boost?
From the sounds of it, he's not interested in using megasquirt for fuel/ignition control, JUST to control his variable geometry turbocharger. So IMO it'd be complete overkill. If he was using megasquirt already for his EFI, I would say it'd be worth it to tweak megasquirt to handle it in addition to everything else.
If that's the case then there's a stand-alone basic microcontroller circuit and prog outline at the Yahoo MS site files section here if it's any help: http://autos.groups.yahoo.com/group/meg ... /Circuits/
It might save some effort - or maybe not...
Thanks guys... I know for certain you are right. There are much more efficient ways to achieve what I need rather than using an entire engine management controller to modulate one dumb output. Unfortunately, I don't have any electronics skills. I'm a wiz at turbos, installs, and calibration but know nothing about writing software or assembling electronics hardware. I was looking for ANY kind of off the shelf device that could take basic engine sensor inputs and turn it into a single PWM (250Hz) output. Now that I have explained my skillset, are there any other ideas other than using a Megasquirt plus maybe the GPIO board? I know it's crazy expensive for what I need to achieve, but I can't find any other options.
My engine is currently set up with twin wastegate turbos and I am in the process of switching to twin variable geometry turbos. Hence the need for controls...
Brock,
I can fully understand where you're coming from. My point was not only is it a very expensive route, but it will likely require just as much electronics wizardry as the much much less expensive routes. Mostly on the software side with the megasquirt, but IMO thats the hardest part of any microcontroller project. With as many competent electronics and software nerds (I mean that in a GOOD way!) I'm sure this forum could help you along. Here's a basic rundown of what I visualize you'd need. Please, those of you with more experience please correct me if I'm wrong.
LM7805 - This is a three pin 5v Voltage regulator. Basicly takes anywhere from ~7v to 35v in and spits out a decent 5v. I think this would be sufficient to power this circuit. Figure a capacitor to smooth out the signal.
PICAXE 18x - This is a easy to use, easy to program for MicroPIC. It has a dedicated programmable PWM output thats suitable for your needs. It also has an easy to use Analog to Digital converter to read your MAP signal. You can load/modify the software via Serial cable, much like you would for Megasquirt. This saves the expense and hassle of an EEPROM burner, probably the biggest setback for most hobbiests trying to get into MicroPIC programming. My only concern with this chip is memory, I can't mentally visualize the amount of code needed here, but this chip has the most memory of any PICAXE chips, with the ability to access more externally via the I2C bus. There is very little support hardware needed to get a picaxe chip up and running on a protoboard.
Some sort of Power Transistor - This will vary depending on how much draw your actuator is going to have. I'm guessing some sort of MOSFET would be ideal. Expect a couple peices of support hardware, namely a diode for back current protection.
And to round it out, you will likely need couple resistors and a couple capacitors for the ADC and pulsin from your RPM signal.
While is may sound a little involved, figure you'll need about the same amount of effort to convert the Megasquirt to work suitably. And also figure all the components above, with all the associated wiring and a nice little plastic project enclosure are likely going to cost no more than $30. If you want a dedicated MAP sensor, figure that onto the total cost.
Thanks for the advice. I may be able to get my wife to help. She writes embedded software, and has done a few PIC projects. Hardware is her weak point, but perhaps we can both learn a little in the process.
-Brock
and I am wondering if this can either be done with the injector output signal or by using the CAN-based GPIO board. Keep in mind I don't nned to control a whole engine, I'm just trying to turn a RPM and MAP signal into a mapped PWM output at 250Hz frequency. Any advice will be appreciated.