用于adc初始化的ARM keil错误

Question

我现在已经在keil工作了一段时间，但是当我为ARM cortex-m4初始化ADC模块并开始调试时，我得到了这个错误：

  

无时钟访问ADC0   必须在SYSCTL_RCGCADC_R中打开位0，然后等待4个周期。

这是初始化代码：

  SYSCTL_RCGC2_R |= 0x00000010;   // 1) activate clock for Port E
  delay = SYSCTL_RCGC2_R;         //    allow time for clock to stabilize
  GPIO_PORTE_DIR_R &= ~0x04;      // 2) make PE2 input
  GPIO_PORTE_AFSEL_R |= 0x04;     // 3) enable alternate function on PE2
  GPIO_PORTE_DEN_R &= ~0x04;      // 4) disable digital I/O on PE2
  GPIO_PORTE_AMSEL_R |= 0x04;     // 5) enable analog function on PE2
  SYSCTL_RCGC0_R |= 0x00010000;   // 6) activate ADC0 
  delay = SYSCTL_RCGC2_R;         
  SYSCTL_RCGC0_R &= ~0x00000300;  // 7) configure for 125K 
  ADC0_SSPRI_R = 0x0123;          // 8) Sequencer 3 is highest priority
  ADC0_ACTSS_R &= ~0x0008;        // 9) disable sample sequencer 3
  ADC0_EMUX_R &= ~0xF000;         // 10) seq3 is software trigger
  ADC0_SSMUX3_R = (ADC0_SSMUX3_R&0xFFFFFFF0)+1; // 11) channel Ain1 (PE2)
  ADC0_SSCTL3_R = 0x0006;         // 12) no TS0 D0, yes IE0 END0
  ADC0_ACTSS_R |= 0x0008;         // 13) enable sample sequencer 3