Learn the most commonly used circuit module principles in a single-chip microcomputer, and you are one step closer to success.

1, dual 232 communication circuit

3-wire connection, corresponding to the female, working voltage 5V, you can use MAX202 or MAX232.

2, triode serial communication

This circuit is built with a triode, the circuit is simple, the cost is low, but the problem is generally very good at low baud rate.

3, single 232 communication circuit

The three-wire method is completely equivalent to the above three-stage tube.

4, USB to 232 circuit

The PL2303HX is used, and the price is cheap and the stability is not bad.

5, SP706S reset circuit

With a watchdog and manual reset, the price is cheap (the letter is much more expensive), R4 is for debugging, and R4 is soldered after debugging.

6, SD card module circuit (with lock)

This circuit is related to the package of the SD card, pay attention to the package. This circuit can control the power of the SD card through the port, which is relatively complete and can be used for 5V and 3.3V. However, it should be noted that the use of some devices, 5V and 3.3 are not the same.

7, LCM12864 liquid crystal module (ST7920)

This circuit is a common 12864 circuit, which is cheap and comes with a Chinese character library. It can be set to the serial port mode or the parallel mode by the level of the PSB port with backlight control.

8, LCD1602 character LCD module (KS0066)

The most commonly used character LCD module can only display numbers and characters, can be controlled by 4 or 8 bits, and has backlight function.

9, full-duplex RS485 circuit (with protection)

With protection function, full-duplex 4-wire communication mode, suitable for long-distance communication.

10, RS485 half-duplex communication module

The transmission direction of the data can be selected by selecting the port to protect the power. This module can only work at 5V.

11, ARM JTAG emulation interface circuit

More perfect, can be applied under the conventional ARM chip, with automatic download function, you can use JLINK or ULINK.

12, 5V power module

This circuit is relatively simple, if you can achieve 1.5A with a straight plug, you can reach 1A with a patch.

13, 3.3 power module

It can reach 800mA, the price is very cheap, and there is a corresponding 1.8/1.2 chip, which can be directly replaced.

14, the most commonly used switching power supply

15, DS1302 digital clock

A very popular clock circuit, easy to use, low cost.

16, AT24C02 (EEPROM)

The most commonly used EEPROM circuit.

17, buzzer drive

This circuit is simple to say.