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Hi,

I am using the usb_serial program from IAN's pic_pack demo example. I have built this program for PIC18F2550, downloaded the hex file

into the chip, wired the chip in bus powered mode as shown in the schematic. Upon plugging into the system nothing comes up. I checked

for the bus voltage & I got 5v with the right polarity. but when I checked the Vusb pin(pin15), I did not get any voltage. I suppose it should

show around 3.3v. what could be wrong?

 

Regards

Raghunathan

USB_SCHEMATIC_FOR_18F2550.zip

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Thanks, I got it to work.

These were my findings while testing..

1) When I plugged my device to different usb port on the laptop the device goes thro' the detection process again and a new com port no. is assigned.

2) Many times I am unable to access the com port with "unable to open com port" message displayed by windows. Can it be made more reliable so that

we can use it for real time Industrial projects?

I use serial port extensively for may of my industrial projects. When I need to access data from different systems

I am forced to use the PCI serial port addon card or the usb to serial converter(similar to picpack emulator). Unable to open com port is one the most common

problems I endup with. So I have decided to use a multiplexer like DG201 to communicate using single com port provided in the PC.

 

I want to know if the same cdc driver, contol transfer function can be used for making devices like the usb key pad or a bar code reader, where the data is printed

where ever the cursor is present. ie be it word or excel or note pad, it should just print where ever the cursor is present.

 

Regards

Raghunathan.

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Hi Raghunathan

 

In my view, using USB for serial comms is a little like using a Ferrari as a tractor.

 

Send me a separate message with your email address, and I'll email you some PIC USB code I have been working on which will address these issues.

 

Tim

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Tim, love to have a look at the stuff you're doing as well - imharris at gmail.com

 

Raghunathan, you should definitely be able to use it each time, every time, but you have to watch how windows magically creates and destroys com ports as you plug / unplug. If you leave the device connected (or have code to handle the com port vanishing when you unplug) then you'll be fine, otherwise, as Time suggests, there may be better way (eg, HID class allows you access to USB data back and forth using default drivers).

 

cheers

Ian.

 

Hi Raghunathan

 

In my view, using USB for serial comms is a little like using a Ferrari as a tractor.

 

Send me a separate message with your email address, and I'll email you some PIC USB code I have been working on which will address these issues.

 

Tim

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