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Megasquirt, MT, Vista and USB->RS232


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I've posted this on the MSEFi forums too, but thought I would post here too as there seem to be quite a few MS users...

After a few problems with version numbers (thanks Fridge and Nige!) I managed to get MegaTune straightened out and loaded with a basic RV8 tune.

However, when MT tries to talk to the ECU, the gauges jump and bounce all over the place - about once/twice a second, but appears in a random rhythm. It almost makes you feel nauseous! However, when using the standard B&G code, the problem is much reduced. It still bounces, but only about once every 45 seconds or so. In the bits when it isn't bouncing - the sensors/values all look normal with both code versions.

I suspect my USB-serial adapter/vista is the cause. I have a cheap eBay adapter (HL-340/CH341), and it passes all the loopback tests you care to do. It is also quite happy flashing firmware to the ECU.

Can anyone suggest why my adapter might be causing this, or could it be something else entirely?

Ooooo...MS1 hardware version 2.2, firmware 029v and it isn't in the vehicle. Simply a PSU connected to the right pins on the connector.

James.

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That'd be awesome if you could. I've got to go in tomorrow to get a decent soldering iron. Mine's packed up.

(I've got a top-secret techy project in place of an ignition key that will need a lot of soldering!)

edit: after looking on their website, they only have two types. One with a wire, and a one piece DB9 connector with a USB socket in the other end....which one do you have?

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There is a whole thread/FAQ on the MSEFI forum devoted to these little blighters (and no, I don't know the link), the long and the short is that they buffer data which works fine if they're connected to a printer or such like but bu**ers things up that need real-time communications. You need to either buy something that's known to work OK with MS (see the forums) or take your chances with whatever you've got.

Or buy a cheapo laptop with a serial port, £50 would probably get something more than capable.

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I got from maplins that sorted it for me

and it has USB to serial that works everytime, I'll see if I can find the exact model

Nige

Same for me and I've just had a hunt around but I cant find the model No. I will find and report.

Jeff

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There is a whole thread/FAQ on the MSEFI forum devoted to these little blighters (and no, I don't know the link), the long and the short is that they buffer data which works fine if they're connected to a printer or such like but bu**ers things up that need real-time communications. You need to either buy something that's known to work OK with MS (see the forums) or take your chances with whatever you've got.

Or buy a cheapo laptop with a serial port, £50 would probably get something more than capable.

Or if you can find a docking station for the laptop/tablet that will give you a serial port.

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Or if you can find a docking station for the laptop/tablet that will give you a serial port.

Can get a bit bulky in a car :unsure: TBH you can buy a laptop that will run MegaTune for ~£50 on eBay, all you need is something that will run Windows 98 and has a serial port. The advantage is that if you get the thing muddy, wet, drop it out of the car etc. you haven't ruined a nice shiny laptop.

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Certainly for MegaJOLT I found the one I bought for an LPG system works faultlessly, the chipset should be 'Prolific' is all that I can remember from the thread mentioned above ^^^

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Prolific make the USB-to-serial chip that lives in the converter box, they're one of the good ones although often you have no idea what's in the box until you buy it and try to make it work - some are total rubbish and do all sorts of weird stuff like appear as a different COM port every time you plug it in <_<

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