The Megasquirt's predecessor was the EFI332 project, led by Bruce Bowling and Al Grippo. EFI332 development started around 1999 and culminated in the release of about 200 kits in 2000. The system used a 32-bit MC68332microcontroller from Motorola. A very steep coding, electronic design, and tuning curve prevented the system from gaining wider acceptance. The designers then decided to simplify the EFI332 design, and focus on managing the fuel injectors. This was the basis for the first MegaSquirt.
Current Products
For a more detailed cross-reference of the features available within the Megasquirt range of products, see
Hardware
The assembled controller takes input from several sensors in order to manage the fuel injectors, including a throttle position sensor, exhaust gas oxygen sensor, MAP sensor, tach signal, intake air temperature sensor, and a coolant temperature sensor. The latter two sensors themselves are usually the General Motors type, although the controller can be recalibrated to use other sensors including Ford and Bosch. As the product has gone through multiple hardware and firmware revisions, it is difficult to be specific about the capabilities of any particular MegaSquirt without knowing three things: microcontroller, printed circuit board and firmware versions.
Microcontroller
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 There is a newer version of the PCB.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 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 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 mainstream 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. 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 and the connectors are in the same places, so it fits in the standard case with no modifications.
Firmware for MS-I chip
standard V3.000 code
'''MS1/Extra
Firmware for MS-II chip
standard MS-II code
MS2/Extra code
Firmware for MS-III chip
standard MS-III code
Licensing issues
The licensing surrounding Megasquirt has at times been misunderstood.
