VEMS
VEMS is a low volume commercial engine management system. VEMS is unlike most other EMS's in that it used to be public domain and then a form of 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 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 components to keep size down and reliability up.
Microcontroller
VEMS uses the AVR Atmega128 which is significantly more powerful than the original MS1 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 is primarily written in the C (programming language), however some parts are distributed in binary and not C for IP protection reasons with an NDA.
Documentation
The VEMS project is poorly documented compared with the MegaSquirt system which many believe is over documented. This has caused adoption of the system to be limited and slow.
Firmware revisions are issued very frequently and it is constant development. Latest firmwares have many advanced features such as double continuous variable camshaft control, GPS and SD card logging, advanced motorsport features (N2O control, transbrake creep etc.).
Tuning Software
Tuning is done with either MegaTune or VemsTune. Until recently Megatune as written by Eric Fahlgren for the MegaSquirt system was only option. MegaTune is licensed under GPL and can therefore be used by anyone. While excellent for 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 firmwares are only compatible with VemsTune, a user interface that was built from scratch and covers all aspects of VEMS tuning (including 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 original MSAVR system is public domain and still available for download. This original source is obviously MegaSquirt based and therefore surrounded by some controversy. Later source was under an open source license, however since 3.2 the system is effectively closed source.
Comparison
"DIY" fuel injection systems
| MegaSquirt | MegaSquirt II | MicroSquirt | MS2 Sequencer | MegaSquirt 3 | VEMS | FreeEMS | |
|---|---|---|---|---|---|---|---|
| Released | 2001 | 2005 | 2007 | Samples under test | 2010 | 2003 | 2008 Continuous releases using git and a build server.[1][2] |
| Processor | 8-Bit MC68HC908 | 16-Bit MC9S12C64 | 16-Bit MC9S12C64 | Dual 16-bit MC9S12C64 | 16-Bit MC9S12XEP100 | AVR Atmega128 | 16-Bit MC9S12XDP512 |
| Speed | 8 MHz | 24 MHz | 24 MHz | 2 x 24 MHz | 50 MHz / 100 MHz | 16 MHz | 40 MHz |
| Flash | 32 kB | 128 kB | 128 kB | 2 x 128 kB | 1024 kB + 32kB | 128 kB | 512 kB |
| User RAM | 512 B | 4 kB | 4 kB | 2 x 4 kB | 64 kB | 4 kB | 32 kB |
| Total IO pins | 34 max with mods | 31 max with mods | 31 max with mods | 62 max | 91 | 53 max | 91 or 119 |
| ADC/ATD pins | 8 (8 bit) | 8 (10 bit) | 8 (10 bit) | 16 (10 bit) | 16, 24 or 32 (12 bit) | 16 (8 bit) | 16 or 24 (10 bit) |
| IC/OC pins | 2 | 6 exposed | 6 exposed | 12 exposed | 8 - 16 | ? | 8 |
| Features/ Benefits | Fuel and COP ignition with msextra, inexpensive, rich feature set. | Fuel and COP ignition with ms2extra, good fuel and ignition accuracy. | Same Features as MS-II, plus small size, sealed case, assembled. | Sequential Injection (8-channels), COP (8-channels), individual trims, uses MS-II and MS-II Extra Firmware, assembled. | Sequential Injection (8-channels), COP (8-channels), individual trims, extension of MS-II Extra Firmware, assembled. | Sequential Injection (8-channels), COP (8-channels + 4 logic-level IGN outputs), WideBand controller, rich feature set, assembled. | Sequential Injection (6-channels), COP (12-channels), individual trims, cheap, uses free open source software and hardware designs, modular clean source code. |
External links
References
- ↑ Cooke, Fred. "Official FreeEMS Build Server". freeems.org website. Retrieved 2012-12-07.
- ↑ Cooke, Fred. "Index Of FreeEMS Vehicles". diyefi.org website. Retrieved 2012-02-27.