With the rapid development of electronic technology and microcontrollers (MCUs), automatic control technology is widely used in the industrial field. Most devices use integrated digital to analog converters for D/A conversion, which increases costs. Therefore, in order to reduce costs, the timer and software inside the microcontroller are used together to achieve PWM output. Through a simple conversion circuit, D/A conversion can be achieved.

Pulse width modulation (PWM) is a method of digitally encoding analog signal levels, which modulates the bias of the transistor gate or base according to changes in the corresponding load to achieve changes in the conduction time of the output transistor or transistor of a switching regulated power supply. This method can keep the output voltage of the power supply constant when working conditions change, It is a very effective technique for controlling analog circuits using the digital output of microprocessors. By using high-resolution counters, the duty cycle of the square wave is modulated to encode the level of a specific analog signal.

PWM control technology has become the most widely used control method in power electronics technology due to its advantages of simple control, flexibility, and good dynamic response. Common application scenarios of PWM include stage lighting, KTV ambient lighting, building decoration lighting, etc.

The MCU application introduced this time is based on the PWM output control of a microcontroller. Through the RC hardware circuit, a timer combined with software is used to achieve PWM output control with adjustable duty cycle and fixed cycle. The general process is to use a potentiometer to change the duty cycle, and through AD conversion, the duty cycle of the PWM square wave is sent to the LED for display. Then, the PWM waveform generated by the given duty cycle is input into a low-pass filter, which converts the input digital signal into an analog signal and then controls the gradient of the LED light.

Program features:

√ Main frequency up to 64MHZ, fast computation and processing speed;

√ Can provide up to 16 PWM channels to drive more LED modules;

√ UART (485 communication) high-speed communication, low latency response between modules;

Application Block Diagram of CW32F030C8T6 in PWM Dimming Control Board

▼ MCU features and advantages:

√ ARM Cortex-M0+32-bit kernel;

√ The highest main frequency is 64MHz;

√ 64K bytes of FLASH and 8K bytes of RAM;

√Four sets of 16 bit universal timers, capable of providing up to 16 PWM channels;

√ 12 bit ADC, 1M SPS conversion speed;

√ Three way UART, two way SPI interface 12Mbit/s, two way I2C interface 1Mbit/s;

√ Power on and power off reset (POR/BOR), programmable low voltage detector (LVD);