Design Of Full Color LED Decoding Chip For Variable Rate DMX512 Protocol

With the rapid development of intelligent lighting technology,DMX512 protocol,an international standard for stage lighting,has been widely applied in the LED control field.Due to the limited carrying capacity of traditional DMX512 protocol of fixed rate,the adaptive variable rate DMX512 protocol has gradually become a new development trend in LED control field.In this thesis,a new decoding algorithm is present to prevent the decoding errors caused by the error accumulation of traditional decoding algorithms.The new DMX512 decoding algorithm reduces the error accumulation of division operation by using the remainder compensation based on the novenary system,and uses the compensation interval distribution to reduce the influence of the error accumulation.The color display effect is optimized by average separated PWM algorithm.And a specific integrated circuit designed for speed change rate DMX512 decoding is completed.The mainly aspects of the research in this thesis are as follows:(1).A novel DMX512 algorithm with the remainder compensation and the compensation interval distribution is present to prevent the error accumulation of traditional decoding algorithms,and the efficient DMX512 decoding with variable transmission is realized;(2).The new DMX512 decoding algorithm is realized by using novenary counting circuit,which avoids the complex division remainder circuit;(3).The average separated algorithm is used to prevent the glint that may occur in LED display with a long machine cycle,by dividing the gray level into two parts and this algorithm manages to improve the refresh rate and optimize the visual effect;(4).An integrated circuit is design with variable rate DMX512 decoding algorithm and average separated PWM algorithm.The circuit was simulated based on Hspice and FPGA to verify the feasibility of the circuit.Compared with the traditional DMX512 algorithm,this algorithm effectively improves the maximum period of the required sampled signal,reduces the possibility of error,expands the range of DMX512 protocol in the environment of variable transmission rate and increases the maximum sampling period available by 12.5 times.Compared with the traditional PWM algorithm,the average separated PWM algorithm effectively improves the refresh rate and optimizes the LED display effect.