递减斜波是一种原理和递增斜波相似的波形，只需将递增斜波的循环加法计数换成1111 1111 1111～0000 0000 0000循环减法计数即可。-Harmonic is a descending ramp and incremental principle similar waveforms, simply incremented counts up the ramp into the cycle of ~ 1111 1111 1111 0000 0000 0000 cycle counti