The invention relates to a PCM
time slot interchange method capable of directly carrying out voice interchange with a voice codec, which comprises the following steps of: taking equipment with a PCM interface as main equipment and a PCM
time slot interchange controller module as the auxiliary equipment of PCM; meanwhile, taking the PCM
time slot interchange controller module as an IIS main equipment interface and a voice
encoder / decoder as an IIS auxiliary equipment interface; designing a time slot switch for a
VHDL code, controlling concrete time slots ascending and descending from the PCM by the time slot switch, finishing the reception and the maintenance of the data of the concrete time slots of the PCM by a PCM time slot interchange controller module, forming a novel IIS
bus timing and transmitting the novel IIS
bus timing to the voice
encoder / decoder; and meanwhile, transmitting
voice data transmitted from the voice
encoder / decoder to the ascending concrete time slots after carrying out frequency-conversion
processing on the
voice data, thereby finishing real-time interchange. The invention can solve the problem of real-time transmission of voice without the participation of a CPU and a memory and also does not need to compile an IIS driver.