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我通过示波器看到，当切换到第二个设备枚举时，第一个设备的SOF停止发送了，所以才导致仅有最后一个设备能够正确操作。 请问各位大虾： 是SL811的某个寄存器设置不正确，还是什么原因？郁闷中。。。 令附SL811寄存器设置程序： int speed_detect(void) { unsigned char i=0,j=0; gbv_full_speed = 1; drv_SL11Write(cSOFcnt,0xAE); // Set SOF high counter, no change D+/D-, host mode drv_SL11Write(CtrlReg,0x08); // Reset USB engine, full-speed setup, suspend disable delay(300); // Delay for HW stablize drv_SL11Write(CtrlReg,0x00); // Set to normal operation drv_SL11Write(IntStatus,0xFF); // Clear Interrupt enable status i=drv_SL11Read(IntStatus); if(i & 0x40) { drv_SL11Write(IntStatus,0x40); return(0x0A); } else { if((i & 0x80)==0) { // Checking full or slow speed, drv_SL11Write(cSOFcnt,0xee); // Set up Master and Slow Speed direct and SOF cnt high=0x2e drv_SL11Write(cDATASet,0xe0); // SOF Counter Low = 0xe0; 1ms interval drv_SL11Write(CtrlReg,0x21); // Setup 6MHz and EOP enable gbv_full_speed = 0; //低速 } else { drv_SL11Write(cSOFcnt,0xae); // Set up Master and Slow Speed direct and SOF cnt high=0x2e drv_SL11Write(cDATASet,0xe0); // SOF Counter Low = 0xe0; 1ms interval drv_SL11Write(CtrlReg,0x05); // Setup 48MHz and SOF enable } drv_SL11Write(EP0Status, 0x50); drv_SL11Write(EP0Counter, 0); drv_SL11Write(EP0Control, 0x01); // start generate SOF or EOP drv_SL11Write(IntStatus,0xff); delay(25); // Hub required approx. 24.1mS drv_SL11Write(IntStatus,0xff); i = drv_SL11Read(IntStatus); // Read Interrupt Status if(i & 0x40) return(0x0D); else return 0; } }