c54x dsp的中断为低电平沿触发。当产生低电平时，输出给vc5402的int1引脚，每按一次，产生一个低电平脉冲。-C54x DSP interrupt for low level along the trigger. When leads to low electricity at ordinary times, vc5402 output to the int1 pin, each as a, produce a low level pulse.