SECU-3

SECU-3 project logo
Old SECU-3 project logo
SECU-3T revCU6 USB with MAP
SECU-3L with MAP and ignition coil drivers
SECU-3 system structural diagram (SECU-3T version)

SECU-3[1] is an internal combustion engine control unit. Open source project (drawings, schematic diagrams, source code etc are open). Anyone can take part in the project and can access all information without registration.

Device controls the ignition, fuel injection and various other actuators of the internal combustion engine (ICE) and vehicle. In particular, it is capable of controlling the carburetor's choke using a stepper motor (auto choke), thus controlling RPM when engine is warming up. Manages AFR on the carburetor (like AXTEC AFR systems), idle cut off and power valve on carburetor, electric fuel pump etc. Unique opportunities for reassigning the I/O functions. Smooth speed control of the cooling fan motor. The ability to edit the main settings and maps in real time (when engine is running). And other features and functions (see below).

Currently, there are three modifications of the unit:

  1. SECU-3. The first version of the unit developed in 2007, controls ignition, cooling fan and some other functions. In the latest software releases, support for this unit has stopped.
  2. SECU-3T.[2] It can control the ignition and fuel injection. It does not contain built-in power drivers for ignition coils, fuel injectors and idling air control (IAC) valve. It is necessary to use external drivers.
  3. SECU-3L.[3] It designed for ignition control only and it can be viewed as a lightweight version of the SECU-3T unit. It contains built-in drivers for ignition coils and manifold absolute pressure (MAP) sensor. It is fully software compatible with SECU-3T unit.

The author also plans to develop new modification of unit with an extended number of I/O and built-in drivers for ignition coils, injectors and IAC actuator.

Device performed on the 8-bit AVR microcontroller ATMega644, with 64kB memory (ROM), 4kB random access memory (RAM), and operates at a clock frequency of 20 MHz. It includes analog and digital inputs, chip for preprocessing signal from the knock sensor (KS), a signal conditioner for reference VR sensor, a signal conditioner for the crankshaft position (CKP) sensor, interface with a computer and outputs for actuators control.

Structural diagram of the system with SECU-3T unit:

SECU-3 system structural diagram (SECU-3T version)
SECU-3 system structural diagram (Lite version)
Example of wiring diagram of the SECU-3T unit for controlling of fuel injection

Structural diagram of the system with SECU-3L unit is shown on the following picture:

SECU-3 system structural diagram (Lite version)

Example of wiring diagram of the SECU-3T unit for controlling of simultaneous or semi-sequential fuel injection on the 4-cylinder engine is shown on the picture below. Hi-z injectors and stepper IAC valve are used. On the right side of picture we can see external connector functions which should be remapped to specified values. It is done in the SECU-3 Manager software.

Example of wiring diagram of the SECU-3T unit for controlling of simultaneous or semi-sequential fuel injection. Hi-z injectors, stepper IAC

History

The first version of SECU-3 was launched in October 2007 and successfully works on the author's (A.Shabelnikov) vehicle for now. Since then, the project has received a lot of new features and synchronization methods. First discussing of the project was started in 2007 in one topic on the iXBT conference.[4] Since Dec. 2010 discussion moved to the forum on diyefi.org.[5] In 2013 own project's forum had been opened.[6] The system has evolved from the ignition control to the engine management system (ECU). The project is supported by author all the time.

Current status

Continue to develop and extending fuel injection features. Also, gas doser features in active development.

Features of the current firmware related to fuel injection:

License

GPL, TAPR OHL

Features

Additional features:

Version differences

SECU-3 SECU-3T SECU-3T revC and later SECU-3L (Lite)
Date 2007 2012 2014 2015
MCU ATmega16, ATMega32 ATMega32 ATMega644 ATMega644
Features Wasted spark, synchronization from CKP sensor full-sequential ignition,

synchronization from Hall sensor, CKP sensor, CKP + reference sensor,

automatic control of carburetor's choke,

immobilizer with iButton key,

optional embedded bluetooth

 same, plus fuel injection control,

AFR control on carburetor,

programmable outputs

 Lite version, intended only for ignition control.

Simplified installation and wiring.

Main connector DB-25 MiniFit 24 pin MiniFit 14+12 pin MiniFit 14pin
Interface RS-232 with optical insulation RS-232 with optical insulation or USB USB Insulated USB

References

  1. ↑ http://SECU-3.org
  2. ↑ Shabelnikov, A.A. (2015). "Electronic control unit for internal combustion engine SECU-3". Visnik Nacional'nogo tehnichnogo universitetu «HPI» (Kharkiv Polytechnic Institute) 156 (22): 90–95.
  3. ↑ Shabelnikov, A.A. (2015). "Ignition control system for internal combustion engines SECU-3L (Lite)". BULLETIN OF THE NATIONAL TECHNICAL UNIVERSITY “KHARKIV POLYTECHNIC INSTITUTE” Series: "New solutions in modern technologies" (Kharkiv Polytechnic Institute) 155 (46 (1155) 2015): 115–121.
  4. ↑ http://forum.ixbt.com/topic.cgi?id=48:5576
  5. ↑ http://forum.diyefi.org/viewforum.php?f=47
  6. ↑ http://SECU-3.org/forum

External links

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