我在使用Protel DXP画完MP3电路图后，执行编译操作（ERC检查），得到许多的显示错误的信息，
具体信息如下：
Class Document Message
[Warning] AUDIO.SCH Extra Pin R509-1 in Normal of part R509
[Warning] AUDIO.SCH Extra Pin R509-2 in Normal of part R509
[Warning] AUDIO.SCH Extra Pin R509-1 (Inferred) in Alternate 1 of part R509
[Warning] AUDIO.SCH Extra Pin R509-2 (Inferred) in Alternate 1 of part R509
[Warning] AUDIO.SCH Extra Pin R511-1 in Normal of part R511
[Warning] AUDIO.SCH Extra Pin R511-2 in Normal of part R511
[Warning] AUDIO.SCH Extra Pin R511-1 (Inferred) in Alternate 1 of part R511
[Warning] AUDIO.SCH Extra Pin R511-2 (Inferred) in Alternate 1 of part R511
[Warning] AUDIO.SCH Extra Pin R520-1 in Normal of part R520
[Warning] AUDIO.SCH Extra Pin R520-2 in Normal of part R520
[Warning] AUDIO.SCH Extra Pin R520-2 in Normal of part R520
[Warning] AUDIO.SCH Extra Pin R520-1 (Inferred) in Alternate 1 of part R520
[Warning] AUDIO.SCH Extra Pin R520-2 (Inferred) in Alternate 1 of part R520
[Warning] AUDIO.SCH Extra Pin R521-1 in Normal of part R521
[Warning] AUDIO.SCH Extra Pin R521-2 in Normal of part R521
[Warning] AUDIO.SCH Extra Pin R521-1 (Inferred) in Alternate 1 of part R521
[Warning] AUDIO.SCH Extra Pin R521-2 (Inferred) in Alternate 1 of part R521
[Warning] AUDIO.SCH
[Warning] AUDIO.SCH Extra Pin R517-2 (Inferred) in Alternate 1 of part R517
[Warning] POWER.SCH Global Power-Object 3.3V at 73000000,49000000has been reduced to local level by presence of port at 810,490
[Warning] POWER.SCH Sheet contains duplicate ports Port 3.3V at 810,490 and 770,330
[Warning] POWER.SCH Sheet contains duplicate ports Port 3.3V at 770,330 and 160,630
[Warning] POWER.SCH Sheet contains duplicate ports Port USB5V at 330,490 and 160,610
[Warning] MP3.SCH Unconnected Sheet Entry POWER-3.3V(Passive) at 190,1390
[Warning] MP3.SCH Unconnected Sheet Entry AUDIO-3.3V(Passive) at 60,1380
[Warning] MP3.SCH Unconnected Sheet Entry AUDIO-AGND(Passive) at 60,1360
[Warning] MP3.SCH Unconnected Sheet Entry POWER-GND(Passive) at 190,1370
[Warning] MP3.SCH Unconnected Sheet Entry AUDIO-LRCLK(Passive) at 160,1420
[Warning] MP3.SCH Unconnected Sheet Entry AUDIO-MCLK(Passive) at 160,1400
[Error] MP3.SCH Net NetU2_8 contains floating input pins (Pin U2-8)
[Warning] MP3.SCH Unconnected Pin U2-8 at 510,140
[Error] MP3.SCH Net NetU2_10 contains floating input pins (Pin U2-10)
[Warning] MP3.SCH Unconnected Pin U2-10 at 660,150
[Warning] MP3.SCH Unconnected Sheet Entry AUDIO-SCLK(Passive) at 160,1380
[Warning] MP3.SCH Unconnected Sheet Entry AUDIO-SDATA(Passive) at 160,1360
[Warning] MP3.SCH Unconnected Sheet Entry POWER-USB5V(Passive) at 190,1410
[Warning] MP3.SCH Unconnected Sheet Entry POWER-VLCD(Passive) at 190,1350
[Warning] MP3.SCH Nets Wire P1.6 has multiple names (Net Label P1.6,Net Label SCL)
[Warning] MP3.SCH Nets Wire P1.7 has multiple names (Net Label P1.7,Net Label SDA)
[Warning] POWER.SCH Sheet contains duplicate ports Port 3.3V at 160,630 and 770,330
[Warning] POWER.SCH Sheet contains duplicate ports Port 3.3V at 770,330 and 810,490
[Warning] POWER.SCH Sheet contains duplicate ports Port USB5V at 160,610 and 330,490
[Error] AUDIO.SCH Net NetU5_3 contains floating input pins (Pin U5-3)
[Error] AUDIO.SCH Net NetU5_4 contains floating input pins (Pin U5-4)
[Error] AUDIO.SCH Net NetU5_1 contains floating input pins (Pin U5-1)
[Error] MP3.SCH 3.3V contains Output Pin and Power Pin objects (Pin U5-7,Pin U2-16)
[Warning] MP3.SCH Net TXD has no driving source (Pin U1-26,Pin U2-11)
[Warning] MP3.SCH Net RXD has no driving source (Pin U1-25,Pin U2-12)
[Warning] AUDIO.SCH Net NetU5_3 has no driving source (Pin U5-3)
[Warning] AUDIO.SCH Net NetU5_4 has no driving source (Pin U5-4)
[Warning] MP3.SCH Net NetJ1_2 has no driving source (Pin J1-2,Pin U2-13)
[Warning] MP3.SCH Net NetU2_8 has no driving source (Pin U2-8)
[Warning] MP3.SCH Net NetU2_10 has no driving source (Pin U2-10)
[Warning] AUDIO.SCH Net NetU5_1 has no driving source (Pin U5-1)
[Warning] AUDIO.SCH Net NetC521_1 has no driving source (Pin C521-1,Pin R517-1,Pin R518-2,Pin U6-6)
[Warning] AUDIO.SCH Net NetC526_1 has no driving source (Pin C526-1,Pin R511-2,Pin R520-1,Pin U6-3,Pin U6-5)
[Warning] AUDIO.SCH Net NetC528_1 has no driving source (Pin C528-1,Pin R509-2,Pin R510-1,Pin U6-2)
[Error] MP3.SCH Duplicate Net Names Wire 3.3V
[Error] MP3.SCH Duplicate Net Names Wire USB5V
//////////////////////////////////////////////////////////////////////
经过漫长的摸索，我的文件编译操作终于通过了。大致有几类错误,
现总结如下：
一， [Warning] AUDIO.SCH Extra Pin R509-1 in Normal of part R509
[Warning] AUDIO.SCH Extra Pin R509-2 in Normal of part R509
[Warning] AUDIO.SCH Extra Pin R509-1 (Inferred) in Alternate 1 of part R509
出现此类警告的原因 ：在 AUDIO.SCH文件中的所有电阻封装不可用。
解决的办法：对 AUDIO.SCH文件中的所有电阻从新调换。
二， [Warning] POWER.SCH Global Power-Object 3.3V at 73000000,49000000has been reduced
to local level by presence of port at 810,490
出现此类警告的原因 ：在POWER.SCH文件中电源标号Global Power-Object 3.3V和端口port 重复定义.
解决的办法：对 POWER.SCH 文件中去掉多余的电源标号Global Power-Object 3.3V。
三, [Warning] POWER.SCH Sheet contains duplicate ports Port 3.3V at 810,490 and 770,330
[Warning] POWER.SCH Sheet contains duplicate ports Port 3.3V at 770,330 and 160,630
[Warning] POWER.SCH Sheet contains duplicate ports Port USB5V at 330,490 and 160,610
出现此类的警告的原因 ：在POWER.SCH文件中网络标号 ports Port 3.3V 重复定义.
解决的办法：对 POWER.SCH 文件中去掉多余的网络标号 ports Port 3.3V。
四, [Error] MP3.SCH Net NetU2_8 contains floating input pins (Pin U2-8)
出现此类错误的原因 ：在MP3.SCH文件中集成元件U2包含有浮空的输入引脚.
解决的办法：对 POWER.SCH 文件中集成元件U2包含有浮空的输入引脚8(此脚不用)放置忽略标记。