Hardware circuit design based on STC microcontroller

ISP (In-System Programming) is programmable in the system, which means that the blank devices on the circuit board can be programmed to write the end-user code without the need to erase or reprogram the circuit board. To download the device, the 8051-programmed single-chip machine can also be programmed with ISP. It is more complicated to use a programmer or emulator, but STC12C5410AD supports ISP. As long as the circuit in Figure 5 is added, the program to be debugged can be written to the microcontroller on the circuit board by using the ISP download software on the PC side of the STC microcontroller through the serial port. The network labels RxD and TxD in the figure below are connected to the P3.0 port and P3.1 port of the STC12C5410AD microcontroller respectively.

2.3 Button Circuit

Since the Io port resources are limited and STCl2C5410AD has its own AD conversion, AD conversion is used for key scanning, and the key circuit is shown in Figure 6. The BUTTON network label is connected to the P1.0 AD conversion port of the microcontroller.

2.4 LCD display circuit

The LCD display circuit is shown in Figure 7. Because the Io port of the STC12C5410AD microcontroller is limited, and the 1602 LCD screen requires 8 data ports, a 74HC164 chip is used to convert the serial port input into the parallel port output, and a 74LS273 latch chip is added to prevent unnecessary data from being sent to the 1602 LCD screen during the serial shift-in process, resulting in display errors.

2.5 Calendar clock circuit

The calendar clock circuit is shown in Figure 8. It uses the DS1302 chip launched by Dallas, which is an IIC interface chip. The STC12C5410AD microcontroller does not have an IIC communication port, so two IO ports are used to simulate the IIC interface through software. The two network labels DS1302_SCLK and DS1302_DATA are connected to the P2.2 and P2.3 ports of the STC12C5410AD microcontroller, and a 10K pull-up resistor is added to each of these two u. The RST_DS1302 network label is connected to P0.0 to reset the DS1302 chip.

2.6 Temperature measurement circuit

The temperature measurement circuit is shown in Figure 9. It uses the single-bus digital temperature sensor DS18B20 from Dallas Company. Therefore, it is not necessary to add an analog-to-digital conversion circuit and directly connect its DQ pin to an IO port of the microcontroller.

2.7 FLASH Circuit

The circuit is shown in Figure 10. AT25F512 is a Flash chip with SPI interface. STC12C5410AD has its own SPI communication port. SCK, MISO, MOSI and Ss network labels are connected to P1.7, P1.6, P1.5 and P0.3 of the microcontroller respectively, and a 10K pull-up resistor is added to each.

2.8 DA conversion circuit

The DA conversion circuit is shown in Figure 11, which uses the PWM function of the microcontroller to achieve DA conversion.

3 Conclusion

This paper proposes a design of hardware circuit for a learning platform based on STC12C5410AD microcontroller. Compared with the traditional 8051 microcontroller, the method of designing circuits with STC12C5410AD microcontroller is somewhat different. It does not have the ALE (address latch) pin of 8051, so its PoEl cannot be used as an address data multiplexing port. Most of the hardware circuits of the learning platform use serial port chips, including most mainstream serial port standards. LCD screen is used instead of digital tube for display, FLASH storage chip is added, and PWM function of STC12C5410AD is used to realize DA conversion, making full use of the resources of STC12C5410AD microcontroller. At the same time, the chip has its own watchdog hardware circuit and M function of II subject, which is suitable for use as a learning platform for teaching experiments.