Multi-Channel PWM Signal Generation Method and Its Application on Robot Toy Control

摘要

The aim of this research considered in this paper is to show a novel multi-channel PWM (pulse width modulation) signal generation method for the multi-joint RC robot driving. Integrating the I/O pins of the microcontroller and the interrupt function of the built-in timer, the maximum PWM channel number is identical to the number of I/O pins and can be used to drive the multi-joint robot. Firstly, configure the timer to generate a preset period clock as the interrupt time base and preset the I/O pins at HIGH level. Secondly, design a corresponding interrupt subroutine to control the duty cycle of each PWM channel. In the interrupt subroutine, an interrupt counter is incremented for every interrupt happened and can be used for the duration calculation of each pin's HIGH level output. Assume the duty cycle of each PWM channel is calculated in each control cycle beginning. Comparing the preset duty cycle of each channel and the time of duration, the corresponding pin will be reset as zero if the equal condition is achieved. Therefore, the duty cycle of each PWM channel is under control. Also, based on the precise time base, a preset interrupt counter bound is used to tune the PWM period. Once the upper bound of interrupt counter is achieved, the interrupt counter will be reset as zero and all the pins' outputs are reset as HIGH level again. Applying this novel scheme to the 18 joints RC robot control, without any other extra chips or components, the smoothing motion control demonstrated the feasibility of the proposed scheme.