MegaSquirt is the registered trademark of an aftermarket electronic fuel injection (EFI) controller designed to be used with a wide range of spark-ignition internal combustion engines (i.e., not diesel engines.) It is a complete standalone fuel injection controller with software and hardware, developed by Bruce Bowling and Al Grippo, developers that work on the US East Coast. The software for the platform is open for modification (for use on Bowling and Grippo hardware only). The hardware provides for only fuel, ignition and idle air control in most cases, keeping the cost low (though there are user configurable outputs in most cases for other functions). The hardware is open in that the schematics are available for troubleshooting and educational purposes, but not for copying. The product is aimed at the DIY market as in most cases MegaSquirt requires assembly and tuning by the user. Basic costs can be below US$300 as of 2009, although this will vary widely depending on application.
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The Megasquirt's predecessor was the EFI332 project, led by the same people. EFI332 development started around 1999 and culminated in the release of about 200 kits in 2000. The system used a 32-bit MC68332 microcontroller from Motorola. A very steep coding, electronic design, and tuning curve prevented the system from gaining wider acceptance.[1]
The designers then decided to simplify the EFI332 design, and focus on managing the fuel injectors (the EFI332 was also designed to control the spark plug ignition system if so desired). This was the basis for the first MegaSquirt (MS-I).
MegaSquirt | MegaSquirt II | MicroSquirt | MicroSquirt module | Megasquirt III[2] | |
---|---|---|---|---|---|
Released | 2001 | 2005 | 2007 | 2009 | 2010 |
Processor | 8-Bit MC68HC908 | 16-bit MC9S12C64 | 16-bit MC9S12C64 | 16-bit MC9S12C64 | 16-bit MC9S12XEP100 |
Speed | 8 MHz | 24 MHz | 24 MHz | 24 MHz | 50 MHz (+100 MHz XGATE) |
Flash | 32 kB | 128 kB | 128 kB | 128 kB | 1024 kB + 32kB data flash |
User RAM | 512 B | 4 kB | 4 kB | 4 kB | 64 kB |
Features | Depends on firmware, Inexpensive | More precise fuel control, Ignition Control, CAN Bus, GPIO, Inexpensive, User Spare Output Ports, Automatic Mixture Control, Flex fuel (E85) abilities | Same Features as MS-II, plus Small Size, Sealed case, Dual Ignition/Injection Channels, Assembled | Single card complete MS2 based ECU designed to be used as the basis of an ECU of the user's creation. Includes firmware license. | Extension of MS2, V8 sequential fuel and spark, many more i/os. Wide range of OEM crank/cam wheels supported. Many racing features built in. Onboard USB-serial, SD card datalogging. See the detailed cross reference. |
For a more detailed cross-reference of the features available within the Megasquirt range of products, see MegaSquirt product cross reference
There are several products due out of the MegaSquirt camp in the future. The main ones are GPIO, and the Sequencer. GPIO was scheduled to be available for sale in mid-2009. Similarly the Sequencer is due to come out some time after GPIO. For more details of the Sequencer and GPIO see the www.msefi.com forums or www.msgpio.com.
The assembled controller takes input from several sensors in order to manage the fuel injectors, including a throttle position sensor (TPS), exhaust gas oxygen sensor (EGO or O2 sensor), MAP sensor, tach signal (or crank position sensor), intake air temperature sensor (IAT), and a coolant temperature sensor (CLT). The latter two sensors themselves are usually the General Motors type, although you can recalibrate the controller to use other sensors including Ford and Bosch.
As the project has gone through multiple hardware and firmware revisions, along with parallel projects that effectively "forked" the project and interlinked compatibilities, it is difficult to be specific about the capabilities of any particular MegaSquirt without knowing three things: microcontroller, printed circuit board and firmware versions.
The version 1.0 MegaSquirt used an 8-bit Motorola MC68HC908 microcontroller, and all versions of the main board support this processor. The later MegaSquirt-II processor upgrade daughter card includes a 16-bit MC9S12, and is a step up from the original MC68HC908 processor MegaSquirt. The current Megasquirt-III uses a 16bit MC9S12XEP100 processor running at 50 MHz which includes a 100 MHz RISC core.
The first group buy of printed circuit boards was performed in 2001. These boards are V1.01 main boards, and are no longer available. The second group buy in 2002, as well as all following purchases until 2005 are V2.2 main boards, and have a V2.2 printed in the upper left corner of the PCB. MegaSquirt ECU's have not been sold by group buy since 2002. Instead, vendors resell the Bowling and Grippo offerings, and they keep stock current, so all items are normally available at all times. There is a list of vendors in the megamanual. Starting in July 2005, the V3 PCB was made available to use some of the advanced features of the MegaSquirt-II. As of August 2007, the v2.2 and v3 boards are still available.
There is a newer version of the PCB. The V3.57 is a surface-mount device (SMD) version of the MegaSquirt V3 'thru-hole' main board. The 3.57 version of the board was created in order to allow for automated assembly of the majority of components using automated pick and place (machine assembly) and reflow soldering. The boards are meant for those unable or unwilling to assemble their own main board. Note that the V3.57 board is not a replacement for the 'build-it-yourself' boards, but rather an additional version of the MegaSquirt main board intended to make life easier for distributors who are building their boards for resale, to compete with main stream ECU suppliers.
Although this board uses surface-mount components, the layout is the same as in the V3 main board, apart from the omission of the DIY-oriented prototype area (the 3.57 is not meant to be a DIY board, of course). Component numbering remains the same in nearly all cases. In fact, this board version started with the V3 main board, and maintains the 4-layer construction and power distribution. It is the same size (4" x 6") and the connectors are in the same places, so it fits in the standard case with no modifications (though some modifications may be necessary for additional functionality).
The licensing surrounding Megasquirt has at times been misunderstood.