Al Grippo and Bruce Bowling have created on MegaSquirt-II, which is a plug-in daughter card which replaces the MC68HC908GP32 with a MC9S12 processor. MegaSquirt-II is basically a plug-in processor card which has the MC9S12 processor plus support hardware as well as a stepper motor chip, and an ignition module controller.

You simply remove the 68HC908GP32 processor on your existing MegaSquirt^® and plug in the MegaSquirt-II daughter card and their MegaSquirt^® controller is now a MegaSquirt-II® controller - it takes less than a minute to do.

MegaSquirt-II Features

MegaSquirt-II adds the following enhancements over MegaSquirt-I:

• 24 MHz HCS12 processor (C64 version),

  Specification	MC68HC908 (MegaSquirt-I)	MC9S12C64 (MegaSquirt-II)
  CPU core	8 bit	16 bit
  Speed	8 MHz	24 MHz
  Flash	32 Kbytes	64 Kbytes
  User RAM	512 bytes	2048 (2K) bytes

  

• Fuel control to 1 µsec (100 times more resolution than MegaSquirt-I),

• Ignition control MegaSquirt-II code/hardware has the ability to control ignition (full spark timing advance control, dwell control, etc). It supports 1 coil/distributor configuration, and the Ford EDIS 'wasted-spark' system, among others. Input trigger and output parameters are fully user configurable so that many other ignition systems that require a single output signal can be supported, including the V3 main boards VB921 (or BIP373) direct coil control circuit.

• Missing Tooth Trigger Wheel Input: Any M-N missing tooth wheel (M>N, N - the number of missing teeth - must be consecutive) can be used with MegaSquirt-II (V2.5+ code).

• Many user-configurable fuel and timing corrections:

  MegaSquirt-II (v2.6+ code) has user-configurable fuelling corrections for:

  • VE, rpm, and manifold absolute pressure (MAP) in a 12×12 volumetric efficiency (VE) table,
  • Intake (manifold) air temperature,
  • Barometric correction (either initial reading, or full time baro correction with a second MAP sensor),
  • Prime afterstart, and warm-up enrichments based on coolant temperature,
  • Accel enrichment based on rpm (in addition to rate of change of TPS and/or MAP, as well as X-Tau enrichment),
  • EGO feedback (3 algorithms), (and a large number of pre-configured controllers).
  MegaSquirt-II (v2.6+ code) has user-configurable ignition advance timing corrections for:
  • rpm, and manifold absolute pressure (MAP) in a 12×12 table,
  • Coolant temperature,
  • Intake (manifold) air temperature,

• Spare port settings These can be used for things like nitrous control, boost control, ignition module bypass control, and many, many other uses. The general purpose I/O logic in MegaSquirt-II code version 2.3 (and above) allows for the following seven pins to be 're-purposed as 'spare' ON/OFF outputs with two user defined conditions on their activation (with user specified hysteresis):

  • FIdle - PM2 (DB37 pin #30),
  • LEDs (x3),
    • Injection LED - PM3,
    • Accel LED - PM4,
    • Warm-Up LED - PM5.
  • IAC1,2 these are capable of directly driving over 0.5 Amp, sufficient for most automotive relays,
    • IAC1 - PT6,
    • IAC2 - PT7.
  • Knock Enable - PA0.

• CANbus networking for 'inter-board' communications with add-on modules (coming soon!) like:
  • transmission controllers,
  • expanded I/O
  • sequential injection drivers,
  • coil-on-plug ignition
  • etc.

• On-board stepper motor driver for IAC stepper control for most common EFI idle control motors (this requires a few jumpers to be added on the MegaSquirt^® PCB to connect the socket jumpers to the DB37 connector)'

• Ford PWM idle valve support,

• Built-in rev limiter, either 'fuel cut' or 'spark retard',

• 12 x 12 Tuning tables: for Volumetric Efficiency (VE) table, 12 x 12 for Air Fuel Ratio (AFR) table, and 12 x 12 for Spark Advance table. There are separate AFR and VE tables for each injector bank (similar to the dual table code),

• Optional X-Tau accel/decel enrichment: The use has the option to enable the sophisticated X-Tau physical parameter based accel and decel enrichment (V2.6+ code), either in conjunction with, or instead of, the conventional enrichment scheme (both conventional TPS and MAP based accel enrichments are also built into the code, you can configure the ratio of each).

• Independent 12 x 12 dual-tables for VE and WBO₂ AFR target table,

• Flexible spark advance table can have different rpm and kPa bins than VE and AFR tables,

• Automatic Mixture Control: This updates the VE table(s) based on EGO feedback as you drive, tuning the engine automatically.

• 115200 baud serial serial communications rate (vrs. 9600 of MegaSquirt-I).

• MAF and MAF/MAP Blend Support: (V2.8+ code) A major addition to the code is MAF (mass air flow) sensor capability and also a combined MAF/ MAP mode. Rather than calculating the air flow from the VE table and manifold pressure (MAP), the mass air flow sensor measure the amount of air directly.

• Injector test mode: For bench testing of injectors (flow testing or cleaning) MegaSquirt-II (V2.6+ code) has a fully user configurable injector test mode.

• Very inexpensive (~$90 US in 2008).

The processor is from the Motorola HCS12 family. It has plenty of excess capability and is a 16 bit machine allowing as much timing resolution as anyone can practically use. Since it is in the Motorola family the MegaSquirt^® embedded code will port over quite easily, however the MegaSquirt-II code has been converted to the C programming language since there is a free GNU cross-compiler for this CPU. This will make it much easier for others to customize the algorithms to meet their needs.

The MegaSquirt-II daughter card plugs in to the existing MegaSquirt^® processor socket, replacing the MegaSquirt^® 68HC908 processor.

How to Buy MegaSquirt-II Hardware

The price for MegaSquirt-II is about $90 (US) in 2008.

MegaSquirt-II is an add-on option for a standard MegaSquirt^® controller. To learn more about MegaSquirt^® EFI Controller, go to the MegaSquirt FAQ and manual. The assembly, testing, and installation of MegaSquirt^® is covered at those sites. This site deals only with the MegaSquirt-II add-in board.

The distributors listing can be found at:

Full installation instructions are at the MegaSquirt-II installation page.

There is also a huge amount of collective experience and knowledge related to the assembly and installation of MegaSquirt/MegaSquirt-II in various vehicles available on the MegaSquirt^® Forums website.