# VEMS

> Mediated Wiki article. Canonical URL: https://mediated.wiki/source/VEMS
> Markdown URL: https://mediated.wiki/source/VEMS.md
> Source: https://en.wikipedia.org/wiki/VEMS
> Source revision: 1025927223
> License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/)

**VEMS** is a commercial engine management system. VEMS is unlike most other [EMS](/source/Engine_management_system)'s in that it used to be [public domain](/source/Public_domain) and then a form of [open source](/source/Open_source).

## History

The original version of VEMS was called MegaSquirtAVR and was a re-write of the popular but inadequate (at the time) [MegaSquirt](/source/MegaSquirt) system.

## Hardware

VEMS can be purchased as a pre-made board or a complete system with several options in between. Most of the design is built with [SMD](/source/Surface-mount_technology) components to keep size down and reliability up.

### Microcontroller

VEMS uses the AVR Atmega128 which is significantly more powerful than the original MS1 [CPU](/source/CPU).

### Revisions

The early MS based version was called 2.0 however that has been out of circulation for some time. The 3.0 board was the first "GenBoard" variant. Development was closed at 3.2 and the current version is 3.6. All 3.X versions incorporate one or more wide band controller.

## Firmware

VEMS [firmware](/source/Firmware) is primarily written in the [C (programming language)](/source/C_(programming_language)), however some parts are distributed in [binary](/source/Binary_file) and not [C](/source/C_(programming_language)) for [IP](/source/Intellectual_property) protection reasons with an NDA.

### Documentation

[Firmware](/source/Firmware) revisions are issued very frequently and it is constant development. Latest [firmware](/source/Firmware) releases have many advanced features such as double continuous variable [camshaft](/source/Camshaft) control, [GPS](/source/GPS) and [SD card](/source/SD_card) logging, advanced motorsport features ([N2O](/source/N2O) control, [transbrake](/source/Transbrake) creep etc.). New features are Electronic throttle control and can bus.

## Tuning Software

Tuning is done with either MegaTune or VemsTune. Until recently Megatune as written by Eric Fahlgren for the [MegaSquirt](/source/MegaSquirt) system was only option. MegaTune is licensed under [GPL](/source/GPL) and can therefore be used by anyone. While excellent for [Megasquirt](/source/Megasquirt), it does not cover all aspects of VEMS, so complete setup and tuning is impossible. It can and has caused incorrect parameters to be written to VEMS causing unpredictable performance.

At present time (2011) MegaTune is mostly obsolete on VEMS as all recent [firmware](/source/Firmware) versions are only compatible with VemsTune, a [user interface](/source/User_interface) that was built from scratch and covers all aspects of VEMS tuning (including [firmware](/source/Firmware) updates directly from VEMS servers, WBo2 sensor calibration, logging and of course, tuning). Some users who run older configs still use MegaTune but majority is now using VemsTune which, after long developer phase, is now very usable.

## Licenses

The no longer available MSAVR [source](/source/Source_code) was MegaSquirt based and therefore surrounded by some controversy. The code was rewritten and has since version 3.2 been [closed source](/source/Closed_source).

## External links

- [- UK distribution and english support forum](http://www.vems.co.uk/)
- [- Main VEMS site](http://www.vems.hu/)

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Adapted from the Wikipedia article [VEMS](https://en.wikipedia.org/wiki/VEMS) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/VEMS?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.