The circuit diagram seems complicated, but in fact, it is also composed of small pieces of functional modules. Therefore, it is necessary to divide it into blocks according to the large function, and then see what circuit form is achieved in the block, some play an auxiliary role, some play a main role. Below, INFINITECH has sorted out 16 commonly used module circuit analysis for you, hoping to be helpful to you.

1. RS232 communication circuit

Dual 232 communication circuit: 3-wire connection mode, corresponding to the female head, working voltage 5V, can use MAX202 or MAX232.

2. Transistor serial port communication

Triode serial communication: This circuit is made of triode, the circuit is simple, the cost is low, but the problem is generally very good at low baud rate.

3. Single-channel RS232 communication

Single-channel 232 communication circuit: three-wire mode, exactly equivalent to the above three-tube.

4. USB to RS232

USB to 232 circuit: the use of PL2303HX, cheap, stability is good.

5. Reset the circuit

SP706S reset circuit: with watchdog and manual reset, the price is cheap (Mei Xin is much more expensive), R4 is used for debugging, and R4 is welded after debugging.

 

6. SD card module circuit

SD card module circuit (with lock) : This circuit is related to the packaging of SD card, pay attention to the corresponding package. This circuit can control the power supply of the SD card through the port, which is relatively perfect and can be used for 5V and 3.3V. However, note that the use of some devices, 5V and 3.3 are not the same.

7. LCM12864 LCD display circuit

LCM12864 LCD module (ST7920) : This circuit is a common 12864 circuit, the price is cheap, with Chinese character library. The level of the PSB port can be set to work in serial mode or parallel mode, with backlight control function.

8. LCD1602 LCD display circuit

LCD1602 character LCD module (KS0066) : The most commonly used character LCD module, can only display numbers and characters, can be 4 or 8 bit control, with backlight function.

9. Full-duplex RS485 circuit

Full-duplex RS485 circuit (with protection function) : with protection function, full-duplex 4-wire communication mode, suitable for long-distance communication.

10. Half duplex RS485 circuit

RS485 half-duplex communication module: You can select the data transmission direction by selecting the port, with protection power. This module can only work at 5V.

11. JTAG emulation interface

ARM JTAG simulation interface circuit: relatively perfect, can be applied to the conventional ARM chip, with automatic download function, you can use JLINK or ULINK.

12. DC5V output circuit

5V power module: This circuit is relatively simple, if you use in-line can reach 1.5A, if you use the patch can reach 1A.

13. DC3.3V power output circuit

3.3 Power module: can reach 800mA, the price is very cheap, there is also a corresponding 1.8/1.2 chip, can be directly replaced.

14. Commonly used switching power supply circuit

15. DS1302 clock circuit

DS1302 digital clock: a very popular clock circuit, easy to use, low cost.

16. AT24C02 communication circuit

AT24C02 (EEPROM) : The most commonly used EEPROM circuit.