The Solar Traffic Sign control system is called a traffic signal machine, which is mainly composed of a controller, a timer, a decoder, and a second pulse signal generator. The second pulse generator is the standard clock signal source of the timer and the controller in the system. The decoder outputs two sets of signal lamp control signals. After the driving circuit, the signal lamp is driven to work. The controller is the main part of the system, and it controls the timing. The work of the decoder and decoder.
The timer is composed of a counter synchronized with the system second pulse (provided by the clock pulse generator). The counter is required to be cleared to zero under the action of the status signal ST, and then under the action of the rising edge of the clock pulse, the counter starts counting from zero. , To provide the controller with a modulo 5 timing signal TY and modulo 25 timing signal TL.
The counter selects the integrated circuit 74LS163 to carry on the design relatively simple. 74LS163 is a 4-bit binary synchronous counter, which has the functions of synchronous clearing and synchronous setting. It is the low-level active synchronous clear input terminal, it is the low-level active only to synchronize the parallel setting control terminal, the traffic light ASM figure control terminal, CO is the carry output terminal, D0~D3 are the parallel data input terminals, Q0 ~Q3 is the data output terminal. A timer circuit composed of two 74LS163 cascades.
The controller is the core of traffic management. It should be able to control the transition of signal lights in accordance with traffic management rules. The state transition table of the controller can be listed from the ASM diagram, as shown in Tables 12 and 3. Two D flip-flops FF1 and FFO are selected as timing registers to generate 4 states. The conditions for the controller state transition are TL and TY. When the controller is in the Q1n+1Q0n+1=00 state, if TL=0, control The device remains in the 00 state; if the controller switches to the Q1n+1Q0n+1=01 state. These two cases have nothing to do with the condition TY, so they are represented by the irrelevant item "X". The rest of the situation can be deduced by analogy, and the state transition signal ST is also listed in the table.
The main task of the decoder is to translate the four working states of the controller's output Q1 and Q0 into the working states of the six signal lights on lanes A and B.
The above is an introduction to the working principle of the traffic light control system. Through these, everyone should be familiar with the operation of the traffic light control system. I hope that everyone can pay attention to traffic safety when driving and walking, and do not violate traffic laws at will.