Some previous MCU DIY works

1. Battery internal resistance tester made with ATmega8 microcontroller
Article published: "Radio" 2009 Issue 2
For dry batteries and rechargeable batteries, people often use a multimeter to judge their quality. The most basic method is to measure the voltage and judge the quality of the battery based on the voltage. In fact, this method is not very scientific. Normal voltage does not mean that the battery is good. It also depends on whether it has the ability to supply power. This involves another important indicator of the battery: internal resistance. We often see experienced people use the large battery block of the multimeter to directly connect the two ends of the battery to measure the size of the battery short-circuit current. This can roughly estimate the size of the battery internal resistance. Since the current block of the multimeter itself has a certain resistance, it is difficult to accurately measure the internal resistance of the battery. It can often only be used to compare the size of the internal resistance of several batteries. In addition, such measurement is also harmful to the battery.
To accurately measure the internal resistance of the battery, a battery internal resistance tester must be used. The battery internal resistance tester made with the ATmega8 microcontroller introduced here can meet the requirements of amateur use. It can be used to measure the voltage and internal resistance of dry batteries, rechargeable batteries, and mobile phone batteries. By modifying the circuit and program, it can also be used to measure the voltage and internal resistance of batteries used in electric bicycles. 2. Electric vehicle battery capacity measuring instrument Article published: "Radio" 2009 Issue 4 People often measure the capacity of electric vehicle batteries by how far they can ride. This method is more intuitive, but it can only make a rough estimate. To accurately measure the capacity of the battery, the battery can be discharged at a constant current, and the discharge time when the battery voltage reaches the termination discharge voltage can be measured. The discharge time multiplied by the discharge current can get the battery capacity. The battery capacity measuring instrument made with the ATmega8 microcontroller introduced here can be used to measure the capacity of electric vehicle batteries. The measurement results are directly displayed with a four-digit digital tube, and the battery voltage can be measured at the same time. 3. Make a digital power meter using an electronic watt-hour meter Article published: "Radio" 2008 Issue 5 Use a 2.5(10)A electronic watt-hour meter circuit module to make it. You can buy an electronic watt-hour meter (only about 15 yuan) and remove the module for use. The measurement range is 1W~2200W, and the accuracy level is consistent with the accuracy level of the selected watt-hour meter. [page] 4. ATmega8 Experimental Board Article published: "Radio" 2007 Issue 1, Issue 2, Issue 3, Issue 4, Issue 5 Serial Single-chip microcomputer is a very practical subject. To learn this course well, you must do more practical operations. For this reason, I designed an experimental board with AVR single-chip microcomputer ATmega8 as the core, and reduce the difficulty of learning AVR single-chip microcomputers by doing experiments. The circuit of this experimental board is relatively simple and low-cost, and it is very suitable for self-made. On the experimental board, you can conduct experiments such as power control switch, digital voltage meter, digital frequency meter, serial port application and digital password lock. Use the ISP download line to burn the program through the software PonyProg2000. 5. Homemade PIC microcontroller programmer Article published: "Electronic News" 2008 Issue 40 K128 programmer is a PIC microcontroller programmer, which uses USB interface programming and draws power from USB. The programming high voltage is obtained by double voltage rectification of the pulse signal generated by the monitoring chip PIC16F628, thus eliminating the need for an independent power supply. Through making and using K128, I feel that there are several difficulties for beginners: 1. The USB to RS232 serial port conversion chip FT232BM is a surface mount package and must be installed on a PCB board. A universal board cannot be used, and soldering is also difficult when making it yourself; 2. FT232BM needs to install a driver. The host computer software cannot automatically find the programmer. You must find the simulated serial port number in the computer's device manager and then set the serial port in the software. Sometimes there are conflicts with other USB drivers. In response to the above problems, I also found that the host computer software and the programmer's monitoring software were both written for the serial port. I made some modifications to the circuit, removed the FT232BM, used serial port programming instead, and retained the USB port for power, making it very convenient to make and use, and the cost was only half of the original. 6. Torque controller This is a product developed for an electric tool manufacturer to control the force resistance of an electric wrench. When the force resistance reaches the preset value, the motor power supply will be cut off immediately. The microcontroller uses PIC12F675.