New V3.0 versions are here!
MicroSquirt is a fully-assembled surface mount (SMT) version of the MegaSquirt fuel injection controller and is most like the MegaSquirt-II and V3 main board assemblies. The intended use is aimed at motorcycles, snowmobiles, personal watercraft, and other similar applications. Wiring harness is included (approx. 3'). This also comes with an RS232 serial cable.
MicroSquirt is basically the same as the MegaSquirt-II/ V3 main board, with the main difference in the injector drivers, MAP sensor which is external to the case, and connectors (the VR circuit is also different).
- The fuel injector drives will max out at 5 amps each, enough to drive one low-impedance (or 4 high-impedance) injector per bank. To get everything to fit without lots of heat sinking, MicroSquirt uses the ST VND5N07 from STMicroelectronics to drive the injectors. This is not a 'peak and hold' driver, but it does clamp the current at 5 amps, so it can be used with one low-impedance injector per bank, however the close time may be a tad higher (or you can use resistors). For up to 4 high-impedance injectors per bank, it should work fine. For example, for motorcycle use MicroSquirt will be perfect!
- In order to shrink the 'footprint' of MicroSquirt, the MAP sensor was left off the board. An external MAP sensor, such as those from General Motors products, can be used instead. See the MicroSquirt hardware page for more information on MAP sensors.
- We carry and recommend either the GM 3 bar MAP sensor for an easy weather-tight solution, or you can also you an 2.5 bar MPX4250AP which is the standard MegaSquirt MAP sensor, it's designed for PCB mount, but you can get creative if you'd like.
- The board will also use the 35-pin AMPSEAL connector and a sealed case to make a fully sealed unit. Amazingly, the board is the physical size of a business card - connector and all. MicroSquirt's board size, including the 35-pin AMPSEAL connector, is very small - 2.4" x 3.5" (61mm x 89mm), just slightly bigger than a credit card. The case measures:
- Length (end plate to end plate, not including flange): 2.75" (70 mm)
- Length (end plate to end plate, including flanges): 3.75" (95 mm)
- Width: 3.73" (95 mm)
- Height: 1.70" (43 mm)
MicroSquirt also has dual channel ignition logic level outputs as well as both the Variable Reluctor (VR) and optoisolated 'Hall/optical/points' tach inputs.
The bootloader is externally accessible, so there's no need to open the case, even to load new code. And the serial RS-232 signals come out of the AMPSEAL connector (instead of a DB-9 on the front, as with MegaSquirt). The board is sealed in a weather proof enclosure.
To use a GM 1, 2, or 3 bar MAP Sensor with the MicroSquirt
In the illustration:
- A is ground,
- B is the sensor output signal to MicroSquirt,
- C takes 5 Volts from MicroSquirt.
The pins are marked A-B-C on the sensor itself.