ASO: Auxiliary Synchronization Output

The ASO is an output of the MIC5 for synchronizing the MIC5 ignition controller and a connected control unit. The possible applications include detonation control, valve control, and fuel injection control.

The ASO signal is low-active, i.e. the pulse width is defined as the time difference between the raising and falling edge (pulse width = traising – tfalling). The raising edge of the signal marks the configured engine rotation angle. With the variable pulse width, the values can be allocated to the engine rotation angle. A maximum of 20 pulses can be configured for this purpose.

The pulse width is known at the time of the active edge, as the falling edge of the signal precedes the raising edge by the value of the pulse width. The controller calculates the duration of the falling edge from high-level to low-level and then back to the starting value of the high-level.

The ASO signal can be inverted via the configuration. It will then be high-active.

You can configure the auxiliary synchronization output with the MICT. Refer to the section Inputs/Outputs – ASO1 (Auxiliary Synchronization Output).

 

Application of the ASO signal

The following example will illustrate the application of the ASO signal:

  • Four-stroke engine with 6 cylinders
  • Ignition angle 120° - 120°

Synchronization between MIC5 and Valve Controller

Cyl.

Ignition angle in °crankshaft

ASO signal in °crankshaft

Pulse duration in µs

1

0/720

718

160

2

120

118

80

3

240

238

80

4

360

358

80

5

480

478

80

6

600

598

80

 

Schematic Representation (Standard Settings)

*) active edge

The valve controller should receive the active edge of the ASO signal before the top dead center of a cylinder. The first pulse duration should be twice as long and thus mark the beginning of a cycle. The ASO signal generated by the MIC5 increases by 2° each time before the ignition signal from Low to High, as can be seen in the schematic drawing. This edge is analyzed by the valve controller as the active edge.

The ASO signal drops in accordance with the configured pulse duration from High to Low before the active edge. The valve controller then has already measured the pulse duration of the active edge and can provide information on the allocation of the signal. In the example shown here, the first cylinder is marked with a pulse width of 160 µs versus 80 µs for other cylinders. If the valve controller measures a pulse width of 160 µs, the subsequent signal is therefore allocated to the first cylinder. The next signal then corresponds with the second cylinder in the ignition sequence, etc.