Microsquirt Module Hardware

Please Note:

All of these instructions / diagrams are to be used at your own risk, like most things there is more than one way to do the same thing, what we have tried to do is to offer a method that we have tested or that others have tested for us. No warranty expressed or implied.

Use at your own risk.

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Microsquirt Module Introduction

Microsquirt module

The Microsquirt module is a bare-board version of the Microsquirt ECU, which in itself is a single card Megasquirt-2 based ECU.
The version 2.2 module was designed specifically to take advantage of the additional inputs, outputs and features that MS2/Extra offers so that is the firmware of choice.

The module is intended to form the basis of your own ECU and purchase of the card gives you license to use any of the Megasquirt 2 firmwares on it. You can create your own ECU around the Microsquirt-module using whatever board(s) or components you see fit.
On example already on the market is the kit form ECU "DIYPNP" from For DIY-PNP specific docs, click here

As the module is intended as the heart of an ECU, it is up to the user to provide interface circuits and suitable connections to "the outside world". If you require a packaged ECU then consider one of the other products in the Megasquirt portfolio.

Connections / wiring

Microsquirt module J2 header

The main 50 pin header connector is J2:

1,2: +12V fused power input
3: 0-5V MAP sensor input
4: Serial RX comms to tuning computer
5: Coolant temperature sensor
6: Serial TX comms to tuning computer
7: Accel LED "D16" mid current ground out, SparkD
8: Bootload, the "boot jumper" rarely used
9: Manifold Air Temp sensor
10: CAN communications H
11: Warmup LED "D15" mid current ground out, SparkC
12: CAN communications L
13: 0-5V Throttle position sensor input
14: VR tach signal no.2 (+) input
15: 5V vref out (for TPS)
16: SpareADC2 0-5V analogue input or digital output
17: SpareADC1 0-5V analogue input or digital output
18: 0-5V Flex fuel input
19: Opto tacho in(+)
20: FIDLE mid current ground out
21: Opto tacho in(-)
22: Fuel Pump mid current ground out
23: VR tach signal no.1 (+) input
24,26,28,30,32: INJ1 out. Use all the INJ1 pins in parallel
25: VR1,2 GND
27: 0-5V Oxygen sensor input
29: Tach "D14" low current ground out
31: Serial GND
33: Sensor GND
34,36,38,40,42: INJ2 out. Use all the INJ2 pins in parallel
35,37,49,41,42,43,45,47,49: Power GND. Use all Power Grounds in parallel
44: IGN2 low current output, SparkB
46: IGN2 out
48: IGN1 low current output, SparkA
50: IGN1 out
Microsquirt module J1 header

The secondary 10 pin header is J1:

1: PA0 Generic output (raw CPU pin)
2: PE1 Input only Tableswitching (raw CPU pin)
3,5: GND
4: ALT_INJ1, digital injector 1 signal
6: ALT_INJ2, digital injector 2 signal
7: PT7 Stepper idle channel (IAC) or additional injector
8: ALT_CAM zero crossing setpoint for VR2
9: PT6 Stepper idle channel (IAC) or additional injector
10: IACEnbl Stepper idle chip enable

Physical dimensions

The two bolt holes on the top/right of the board are ideally used as additional heatsinking for the 5V voltage regulator.

External connections

(Note: this section needs extending)
The sensor inputs to the Microsquirt module are largely the same as other Megasquirt products.
The injector outputs are capable of driving four high impedance (14 ohms) injectors each. If you have low impedance injectors (typically 2.5 ohms) then it is advised to use series resistors or an external peak and hold box. Do not directly connect low impedance injectors if you want reliability.
The logic coil outputs are suitable for driving LS1 type ignitors or other logic ignition modules. Do NOT connect them directly to a coil.

Silkscreen and schematics

Module silkscreen

Schematics are available here


As the module is essentially a Megasquirt2, you should use the MS2/Extra firmware and documentation.
The manual is here.
Be sure to use the forum for any support questions.

Microsquirt Utility board

Microsquirt module utility board
The utility board provides screw terminal access to the J2 connections on the Microsquirt module. It can be used as a compact test bed for the module. However, the pin header has to be soldered on to the top of the Microsquirt card, instead of the bottom as is normally used. Therefore the utility board will require a dedicated module card. Also, there is no provision to use the J1 pin header.
See also a video of the Utility Board.

If you have a question, comment, or suggestion for this FAQ please post it on the forum.

No part of this manual may be reproduced or changed without written permission from James Murray, Ken Culver and Philip Ringwood.