使用PIC32 MZ2048 EFG144作为CDC USB设备

Greetings Larry，斯坦福，谢谢你的邮件。我希望有人使用这个特定的处理器与USB。一般来说，PIC32MZ上的数据表/引用有很多不足之处，需要改进。实际上，我试图在PIC32MZ2048EFG144上使用USB CDC_com_port_.示例，但收效甚微。所有连接已被验证（PC电缆端到PIC32引脚），包括UBID和VBUS电压。该示例使用PIC32 MZ启动器套件EF，它是处理器家族中不同的一个字母，并且包括CAN总线接口。USB的引脚与定制板相同。在选择了正确的处理器、编译和加载之后，代码运行，但是从来没有连接到PC。实际上，在D+和D-pin上有任何类型的零活性。起动器套件使用相同的电缆连接到同一台PC。当代码执行时，USB的VBUS状态和寄存器设置被验证为与启动器套件匹配。PIC32没有故障或任何问题，只是没有尝试与PC进行协商。我甚至尝试过将总线速度改为全速，并用启动器工具包验证了操作，但是italso没有连接。这部分USB的差错是远程唤醒和空闲总线。概述：-PIC32启动器套件EF处理器连接（不是EFG处理器；相同的144引脚包）到PC和示例工作。症状：用正确的处理器重新编译的固件运行，只是没有连接或显示PC侧的任何活动-Starter套件和定制板-USB连接匹配D+，D-，VBUS，USBID；注意VBUS连接没有额外的OTG硬件，直接从主机PC供电-VBUS电压验证在自定义板上显示正确的状态（匹配starter套件）-使用相同的24MHz振荡器（完全相同的部分）-检查每个引脚的连续性，并且不缩写为从PC USB电缆侧到PIC32MZ引脚的其他部分-在两个设置中使用的相同的PC、电缆等-示波器不显示任何USB活动-作为测试修改为使用全速的项目；没有改变行为-次级振荡器不被启用(不是示例代码的一部分)-具有PIC32验证工作的自定义板，除了USB外围设备-固件(不重新编译到自定义目标)显示相同的行为、运行但不连接(部件之间的CAN总线外围设备差异)建议和评论非常感谢，以及任何与USB一起使用这个精确部分的人。谢谢。



      以下为原文

    Greetings Larry.Standage,
 
Thanks for the post.  I'm hoping someone has used this specific processor with the USB.  The data sheet / reference on the PIC32MZ in general has quite a few deficiencies and needs improvement.
 
In reality I'm trying to use the USB CDC_com_port_single example with little success on the PIC32MZ2048EFG144.  All connections have been verified (PC cable end to PIC32 pins), including the USBID and VBUS voltages.  The example used the PIC32MZ Starter Kit EF which is one letter different in the processor family and includes a CAN bus interface.  The pinout for the USB is the same with the custom board.  After selecting the correct processor, compiling, and loading, the code runs, but never connects to the PC.  In fact there is zero activity of any kind on the D+ and D- pins.  The starter kit connects to the same PC using the same cable.  The VBUS state and register setup of the USB are verified to match with the starter kit when the code executes.  No fault or anything else is generated, the PIC32 just does not try to do the negotiation with the PC.  I've even tried changing the bus speed to full speed and verified the operation with the starter kit, but it also does not connect.  The errata for USB on this part is remote wake and idle bus. 
 
Summary:
-          PIC32 Starter kit EF processor connects (Not EFG processor; same 144 pin package) to PC and example works
-          Symptom:  Firmware recompiled with the correct processor runs, just does not connect or show any activity on the PC side
 
-          Starter kit and custom board - USB connections match for D+, D-, VBUS, USBID; note VBUS is connected without the extra OTG hardware and is directly powered from the Host PC
-          VBUS voltage verified on custom board shows correct state (matches starter kit)
-          Same 24 MHz oscillator used (exact same part)
-          Each pin continuity checked, and not shorted to something else from PC USB cable side to the PIC32MZ pins
-          Same PC, cable, etc. used in both setups
-          Oscilloscopes do not show any USB activity
-          Project modified as a test to use full-speed; no change in behavior
-          Secondary oscillator is not enabled (not part of the example code)
-          Custom board with PIC32 verified working, with the exception of the USB peripheral
-          Firmware (without recompiling to custom target) exhibits the same behavior, runs but does not connect (CAN bus peripheral difference between the parts)
 
   Suggestions and comments would be greatly appreciated, along with anyone chiming in that has used this exact part with USB.  Thanks in advance.
 
JMA_1