说明：  尽快掌握STM32的认识，声音的数据是通过WM8978语音芯片获取的。第一次获取到的音频数据以WAV格式保存在外部Flash。 要怎样才能把后面听到的数据跟第一次获取到的音频数据进行一个比较
(Viewing angle is the angle at which the contrast ratio is greater than 2. For TFT module the conrast ratio is greater than 10. The angles are determined for the horizontal or x axis and the vertical or y axis with respect to the z axis which is normal to the LCD surface. For more information see FIG 3.)