SECU-3

SECU-3 project logos

SECU-3T revCU6 USB with MAP

SECU-3L with MAP and ignition coil drivers

SECU-3 Micro ignition controller unit

SECU-3i engine management system unit

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, stepper gas valve with oxygen sensor loopback 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 switching between 2 or 4 sets of maps. And other features and functions (see below).

Currently, there are five modifications of the unit:

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. History of the SECU-3 versions with photos is here
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.
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.
SECU-3 Micro.^[4] Very simple and budgetary ignition controller unit in small plastic enclosure. Has only few inputs and outputs and doesn't contain built-in power drivers for ignition coils. It is the simplest SECU-3 unit.
SECU-3i.^[5] Full-featured, complete engine management system in metallic enclosure with integrated power drivers (for ignition coils, injectors, IAC actuator etc.), extended number of I/O and Bluetooth. The latest author's development. This unit has two boards design.

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) (except SECU-3 Lite and Micro units), a signal conditioner for reference VR sensor (except SECU-3 Micro unit), 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)

SECU-3 system structural diagram (Micro version)

Example of wiring diagram of the SECU-3T unit for controlling of fuel injection

SECU-3T revD U6 assembled board without MAP

SECU-3 Lite assembled board without MAP

Assembled PCB for the SECU-3 Micro unit

Bottom board of the SECU-3i EMS

Top board of the SECU-3i EMS

SECU-3 Manager v3.4 - first tab

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

SECU-3 system structural diagram (Lite version)

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

SECU-3 system structural diagram (SECU-3 Micro 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.^[6] Since Dec. 2010 discussion moved to the forum on diyefi.org.^[7] In 2013 own project's forum had been opened.^[8] 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 extend fuel injection features and algorithms (inter alia, full-sequential injection support). Also, author works on software for the SECU-3i unit.

Features of the current firmware related to fuel injection:

Simultaneous (all injectors open at the same time), central (throttle-body) injection, two banks alternating (two injectors or two banks of injectors fire alternately) and semi-sequential injection (injectors fire by pairs). In the nearest future full-sequential injection support will be added
Speed-density method of estimating airflow into an engine (MAP and IAT sensors are used)
Open-loop IAC (closed-loop algorithm (PID) will be implemented in the nearest future)
Closed loop control of AFR using oxygen sensor. Ability to set voltage threshold, integrator step etc.
Tables: VE, AFR, inj.open time, warm up enrichment, IAC position on cranking, IAC position vs coolant temperature, inj.time on cranking, inj.timing
After start enrichment
Acceleration enrichment (TPS, RPM)
Priming pulse (wetting of intake manifold) vs coolant temperature

License

GPL, TAPR OHL with one addition: developments can not be used in commercial purposes without written approval of author (according to information from the official site).

Features

Support of engines with number of cylinders: 1,2,3,4,5,6,8
Synchronization from CKP sensor and missing tooth wheel or from two sensors and non-missing tooth wheel. Support of 60-2, 36-1 and other wheels with different number of teeth (from 16 to 200)
Synchronization from Hall sensor (you can leave distributor)
Advance angle regulation from engine speed (from 1 VR sensor, 2 VR sensors or Hall sensor)
Advance angle regulation from engine load (from MAP sensor)
Correction of advance angle depending on temperature (various types of coolant temperature sensors)
Correction of advance angle from detonation (from 1 or 2 knock sensors)
Measurement of board voltage
Idle cut-off valve solenoid control
Control of power valve solenoid (part load enrichment valve)
Multichannel output (from 1 up to 6 igniters). It is possible to use up to 8 channels!
Support of 2 channel igniters (single input driven by both edges)
RS-232 interface for reprogramming, control and tuning (with optical isolation) or USB interface (without optical isolation)
Able to control of engine cooling fan (using of PWM is also supported)
Starter blocking when engine speed reaches specified value
Gas equipment support (automatic switch gas/gasoline)
Output for error indication “Check Engine” with support of blink codes
Ability to emergency start of boot loader
Ability to recover settings in emergency case
Idle speed regulation using advance angle
Control of coil’s energy accumulation (dwell control)
Cam sensor support (coil per cylinder – full sequential ignition)
Fuel injection control (central, simultaneous injection)
Injection timing control using map
Calculation of air flow using Speed-Density method
AFR control on carburetor(Solex) by means of valve actuators with closed loop (oxygen sensor)

Additional features:

Control of an electric fuel pump
Tunable pulses output for Hall sensor or tachometer
Embedded stroboscope function (it is possible to use any free output)
Output and input functions remapping
Determine throttle gate position by TPS sensor
Processing and writing to log file signals from 2 additional inputs (e.g. Oxygen sensor can be connected)
Power management (ability of some functions to work after ignition is switched off, for instance working off cooling fan or auto choke control)
Carburetor choke control (using a stepper motor)
Stepper gas valve control
Support of speed sensor (Displaying and writing to log vehicle speed (km/h) and passed distance (km))
Control of manifold heater (also known as grid and intake heaters)
Correction of advance angle using air temperature sensor (connected to one of 2 additional inputs)
3 versatile programmable outputs, which can be programmed by user to perform different actions in very convenient and flexible way

Version differences

	SECU-3	SECU-3T	SECU-3T revC and later	SECU-3L (Lite)	SECU-3 Micro	SECU-3i
Date	2007	2012	2014	2015	2016	2016
MCU	ATmega16, ATMega32	ATMega32	ATMega644	ATMega644	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, stepper gas valve control, programmable outputs	Lite version, intended for ignition control and two additional outputs. Simplified installation and wiring. Ignition coil drivers integrated to the unit.	Maximum simplified version, intended only for ignition control. Has only two ignition outputs and several inputs. Simplified installation and wiring.	The most functional version among SECU-3 units, a full EMS. All the necessary devices are built into the unit (drivers for injectors, ignition, IAC, stepper motor, PWM etc.). The unit consists of two boards, has optional embedded Bluetooth.
Main connector	DB-25	MiniFit 24 pin	MiniFit 14+12 pin	MiniFit 14 pin	MiniFit 12 pin	MiniFit 24+6+14+12 pin
Interface	RS-232 with optical insulation	RS-232 with optical insulation or USB	USB	Insulated USB	USB	Insulated USB

References

↑ http://SECU-3.org
↑ 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.
↑ 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.
↑ Alexey Shabelnikov (2016). "MICROPROCESSOR CONTROLLED IGNITION SYSTEM SECU-3 MICRO". MATERIAŁY XII MIĘDZYNARODOWEJ NAUKOWI - PRAKTYCZNEJ KONFERENCJI AKTUALNE PROBLEMY NOWOCZESNYCH NAUK - 2016. Sp. z o.o. «Nauka i studia». 111: 55–61.
↑ Shabelnikov, A.A. (2016). "SECU-3i PROGRAMMABLE ENGINE MANAGEMENT SYSTEM". Technology, energy, agriculture transport AIC. Vinnytsia National Agrarian University. 112 (2(94)): 67–73.
↑ http://forum.ixbt.com/topic.cgi?id=48:5576
↑ http://forum.diyefi.org/viewforum.php?f=47
↑ http://SECU-3.org/forum

External links

Automotive engine

Part of the Automobile series

Basic terminology	Bore Compression ratio Crank Cylinder Dead centre Diesel engine Dry sump Engine balance Engine configuration Engine displacement Engine knocking Firing order Hydrolock Petrol engine Power band Redline Spark-ignition engine Stroke Stroke ratio Wet sump

Main components	Connecting rod Crankcase Crankpin Crankshaft Crossflow cylinder head Crossplane Cylinder bank Cylinder block Cylinder head Flywheel Head gasket Hypereutectic piston Main bearing Piston Piston ring Reverse-flow cylinder head Starter ring gear Sump

Valvetrain	Cam Cam follower Camshaft Desmodromic valve Hydraulic tappet Multi-valve Overhead camshaft Overhead valve Pneumatic valve springs Poppet valve Pushrod Rocker arm Sleeve valve Tappet Timing belt Timing mark Valve float Variable valve timing

Aspiration	Air filter Blowoff valve Boost controller Butterfly valve Centrifugal-type supercharger Cold air intake Dump valve Electronic throttle control Forced induction Inlet manifold Intake Intercooler Manifold vacuum Naturally aspirated engine Ram-air intake Scroll-type supercharger Short ram air intake Supercharger Throttle Throttle body Turbocharger Twin-turbo Variable-geometry turbocharger Variable-length intake manifold Warm air intake

Fuel system	Carburetor Common rail Direct injection Fuel filter Fuel injection Fuel pump Fuel tank Gasoline direct injection Indirect injection Injection pump Lean burn Stratified charge engine Turbo fuel stratified injection Unit injector

Ignition	Contact breaker Magneto Distributor Electrical ballast High tension leads Ignition coil Spark plug Wasted spark

Electrics and engine management	Air–fuel ratio meter Alternator Automatic Performance Control Car battery (lead–acid battery) Crankshaft position sensor Dynamo Drive by wire Electronic control unit Engine control unit Engine coolant temperature sensor Glow plug Idle air control actuator MAP sensor Mass flow sensor Oxygen sensor Starter motor Throttle position sensor

Exhaust system	Automobile emissions control Catalytic converter Diesel particulate filter Exhaust manifold Glasspack Muffler

Engine cooling	Air cooling Antifreeze (ethylene glycol) Core plug Electric fan Fan belt Radiator Thermostat Water cooling Viscous fan (fan clutch)

Other components	Balance shaft Block heater Combustion chamber Cylinder head porting Gasket Motor oil Oil filter Oil pump Oil sludge PCV valve Seal Synthetic oil Underdrive pulleys

Portal Category

This article is issued from Wikipedia - version of the 11/30/2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.