Bruce Bowling a écrit :MicroSquirt - I (Bruce) have been very quiet the last several months, but I have not been resting. What I have been working on is a true miniaturization of the MS computer, targeted to room-limited setups like motorcycles, etc. The result is a board that is roughly the same size as a credit card (actually 2.6 x 3.5 inches) with all of the MS2 circuitry and V3 board essentials, including a VR tach input (or regular opto), and the VB921 ignition driver. Add to this an AMPSEAL 35-pin connector and a sealed case. The AMPSEAL carries all the ECU I/O, and it has pins allocated for CAN, RS-232 serial, and a bootloader enable wire, and the three front panel LED drive signals - everything comes out of this one connector. The circuitry is pretty much the same as the V3/MSII, with the exception of the injector drivers. The injector drive is not PWM switched, but current-limited to 5 amps, any current draw above 5 amps will be limited. This was done mainly because of the small board size constraints w/ heat dissipation. So, each injector channel (there are two just like the regular MS) can drive up to 4 high-Z injectors directly, but for low-Z injectors the use of an external ballast resistor may be a good idea. The goal is to keep the current draw per channel down to 5 amps or lower in order to keep the overcurrent circuit from kicking in (and generating heat). The flyback voltage (avalanche) on the injector driver is 70 volts, so the close time will be nice and short. The PCB is a 4-layer, and the high-current grounds and power are separate from the digital power.
The other major change is that the MAP sensor is not on the board, so an external sensor will be required. This is not a big issue, since it is easy to define a new MAP sensor curve via. MegaTune.
There are no changes to the processor I/O, so the current MSII code will run direct on the MicroSquirt without any changes.
The status of MicroSquirt is that I have the first prototype board completely tested. In the next few weeks, I will get a beta run of the board made up, and I will have a very limited number of boards for people to test on vehicles. Once this is complete, then MicroSquirt can go to production. Note that this will be a ready-made system and tested, no assembly will be required. Also, the case is a custom made unit for MicroSquirt, and the PCB will be completely sealed. I am not sure if we will use a gasket on the end plates, or just use a potting compound and encapsulate the board within the case. Complete encapsulation will make board rework very difficult, but it will make the unit truly waterproof. A conformal coating may also be the answer, need to investigate this further.
We have not finalized the price for MicroSquirt, but it should bery close to what an assembled MegaSquirt is going for right now, probably in the US$350.00 price range (or slightly higher) - but do not hold me to this, there are a lot of added costs, like custom enclosure, AMPSEAL (this is really pricey), encapsulation, etc. And just getting external wires crimped on the AMPSEAL mating connector is not inexpensive (so you may get to do this yourself . But we will keep the cost as low as possible, like we have done with the MegaSquirt, but allow some margin for the distributors to make a few dollars so that they can keep on providing their excellent service!
There is a start of a MicroSquirt website here -
http://www.microsquirt.info/ - and we will make a MSEFI forum sub-listing when the UC units are available.
) avec coupure de la MS