Seal machine control circuit

Published:2012/8/19 22:31:00 Author:Ecco | Keyword: Seal machine , control | From:SeekIC

(1) It can prevent the program into an infinite loop. In order to improve the system's interference to prevent the program to enter an infinite loop, the system uses the WATCHDOG circuit composed of the counter. 555 is connected as multivibrator with cycle in t0; 74LS93 is connected as hexadecimal counter, when it counts to 8th pulse, QD side becomes high, microcontroller uses P3.7 output to clear pulse. If the cleared pulse interval is shorter than the eight pulse cycle, the counter will never be less than 8, and the QD side keeps low. When CPU receives interference and falls into infinite loop, it can not send reset pulse, the counter will soon count to 8, then QD side goes high immediately, but differential circuit C2 , R3 can output a positive pulse to make CPU is reset.



Reprinted Url Of This Article:
http://www.seekic.com/circuit_diagram/Control_Circuit/Seal_machine_control_circuit.html

Print this Page | Comments | Reading(3)