Trigger is an elementary digital automatic machine

The trigger is the simplest device, which is a digital automaton. It has two states of stability. One of them is assigned the value "1", and the other - "0". The trigger state, as well as the value of the binary information stored in it, is determined by the output signals: direct and inverse. If there is a potential corresponding to a logical unit on the forward output, then this trigger state is called single (the signal level at the inverse output corresponds to a logical zero). If there is no potential, then such a device status is called zero.

Types of triggers. Classification

1. Asynchronous and synchronous triggers are selected according to the way information is recorded. In asynchronous devices, switching occurs when information signals are input. In synchronous, in addition to basic information, there are control inputs (one or more). Such triggers are switched when control signals are received on them.
2. By the method of information management devices are divided into statistical, dynamic, single-stage and multistage. The principle of operation of the trigger in the statistical control consists in switching the device due to the level of the signal arriving at the information inputs, with dynamic control - in changing the potentials entering the inputs of the semiconductor device. Single-stage devices have one control stage, two-stage devices - two. Triggers of synchronous type with single-stage storage of information are called single-cycle, respectively, with a two-stage recording - two-stroke.
3. The JK-trigger, RS-flip-flops, T-flip-flop, D-flip-flop and other types of devices are allocated according to the type of logical connections.

The main parameters of all types of triggers are the maximum duration of the input signal, the delay time required to switch the device, and also the enabling time.

Notation of types of trigger inputs

• R means a separate input of the device setting to zero.
• S - switch the device into a single mode.
• K is the input of the split universal trigger setting to the zero position.
• J - means a separate switching of the semiconductor device into a single state.
• T is the counting input of the device.
• D - the input of the trigger switching to the mode, which repeats the level at the input.
• C - synchronizing input of the device.
• V - control, authorizing input.

The main types of triggers

1. Asynchronous RS-trigger. This device has two stable states and two inputs - R and S.
2. T-flip-flop is the most popular type of semiconductor devices; it has only one information (T) input, it is also called countable. The synchronous RS flip-flop has an additional control (C) input.
3. D-trigger. Devices of this type also have one information (D) input and represent a time delay.
4. The DV flip-flop is essentially the same D flip-flop, but has an additional (V) control input.
5. JK-trigger. This type of device differs from the asynchronous ones in that when the combinations of combinations forbidden for the device are disabled, they invert the stored information.