Simple calculator

• Hardware description

1. Use stc89c52 as the main control chip, 1602 for display, 36 buttons and 3 LED lights, and use micro-usb5V for power supply.
2. PCB design uses plug-in components, and soldering is very simple.
3. Since the circuit is relatively simple, a perforated board is used here for verification. Although the PCB has not been verified, there should be no problem.

• Software description

1. The program will use notation and operator precedence rules to complete complex operations in a small RAM space.
2. The program implements mixed operations such as trigonometric functions (sin/cos/tan/sec/csc/cot), square roots, factorials, addition, subtraction, multiplication and division to meet basic mathematical operation requirements.
3. The implementation of the program uses the idea of ​​modularity, so new functions can be easily added, and other developers can make changes as needed.
4. Since the program has been structurally optimized, it still requires at least 8K of flash space, which almost fills up the chip memory. Some functions cannot be added, such as the inability to check the correctness of calculations. If you need code in this area, you can discuss it with me. Here is one A relatively clever solution, but it has not been proven.

• Engineering indicators

The program has been verified. Since it uses the float data type, the effective number is 7 digits. It can automatically switch between normal and exponential display modes according to different situations, which is very convenient.