5.1.1 STC89C52 chip
The design we used is STC89C52 microcontroller, a programmable blinking with 8k byte erasable read-only memory low-voltage, high-performance COMOS8 microprocessor, the device has a 40-pin, faster, cheap, easy programming via the serial port to download, you can achieve online programming, uses ATMEL high density non-volatile memory manufacturing technology manufacturing, is compatible with the industry-standard MCS-51 instruction set and output pins.
5.1.2 reset circuit
To ensure that the computer system is stable and reliable work of the circuit, reset circuit is an essential part of the basic functions of reset circuit are: to provide a reset signal when the power system until the system power supplies have stabilized, the reset signal revoked. For reliable operation, even after the power is stable after a certain delay before reset cancellation, in case the power switch or plug points - combined jitter caused during impact reset. When the microcontroller reset pin machine cycle occurs two or more high, the microcontroller reset operation is performed. If RST continued high, the MCU is in the reset state cycle. Reset pin capacitance so large that did not matter much, at most, a little longer reset time; but if the capacitance is too small, high duration is too short, can not properly reset the microcontroller, it can not work, or 22UF 10UF capacitor is usually taken , electrolytic capacitors can be.
Microcontroller reset circuit when power is first turned on, the beginning of capacitors are without electricity, resistors and capacitors in the low, after power, 5V power supply through a resistor to charge the electrolytic capacitor, the voltage across the capacitor will slowly from 0V rise to about 4V (in this short period of time is typically less than 0.3 seconds), precisely because of this, the potential of the reset pin from low rise to high potential, causing a reset operation of the internal circuit; when you press the reset button, across the capacitor discharges the capacitor back to 0V, so they conducted a reset operation. Circuit shown in Figure 5.1.