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Hello everyone,
we're using a NXP LPC2368 in a project, that includes connection to a PC via USB (virtual serial connection). When connecting the LPC2368 to a WindowsXP-PC for the first time, a hardware configuration assistent starts. Following this assistent, the user must specify the path to the file 'mcb2300-vcom.inf' that is originally provided with the uVision IDE. This file contains information for installing the correct usb driver for the virtual serial connection. WindowsXP uses a generic driver file 'usbser.sys' to make the USB connection to the LPC2368 work. As we know now, the usbser.sys should have a newer version number, for example 5.1.2600.xxxx. A stable working version of the file is provided by ServicePack3 for WindowsXP.
Here's the problem: On MANY WindowsXP-PCs the hardware configuration manager fails and its not possible to establish the virtual serieal connection. But all the PCs have ServicePack3 installed and consequently an actual version of the usbser.sys generic driver file. We suppose that there's a problem with various usb host controllers used on mainboards, but we can't dictate our customers to use a special hardware in their PCs.
Is it possible that some usb host controllers on mainboards cannot work with LPC2368 in vCOM-Mode? Has anyone ideas to definitely locate and maybe solve the problem? We can't test hundreds of different hardware configurations in PCs...
I'm looking forward to your answers...
> The normal operation is as follows: The device and the PC have to be powered up at first. If the device or PC are not powered up, they should not be plugged together. After powering up, the physical connection between device and PC can be established.
For this operation, you have to choose bus-powered, instead of self-powered. If the peripherals require more than 100mA (or 500mA), make just the MCU bus-powered. And then, MCU enables a regulator which feeds from local supply to the peripherals of heavy load. When the MCU powers down, the regulator cuts off by pull-down attached to the enable pin.
> So, the problem is that, the hardware configuration manager reports that, "Found NO new hardware!"; or the hardware configuration manager just crashes?
When the device behaves unexpectedly, Windows also responds unpredictably. If you want to see solid evidence, monitor the USB line with a hardware bus analyzer.
Anyway, if you don't like to modify your board so much, sort out the firmware for self-powered. Do you want to hear more about self-powered fimware configuration? If not, I'll post it elsewhere.
Tsuneo