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Author Topic: What is VCOM functionality exactly?  (Read 13411 times)

faskrobo

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What is VCOM functionality exactly?
« on: April 18, 2022, 11:53:03 AM »

I've been using an FT4232HL with the libMPSSE library to communicate over SPI, but the documentation mentions a virtual com port and I'm curious what I'd be able to do with it? Is writing to it the same as calling FT_Write() in D2XX, or is it more complicated? And is it possible to communicate over SPI through VCOM interface, or is the VCOM only capable of UART transfer?
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Re: What is VCOM functionality exactly?
« Reply #1 on: April 19, 2022, 04:54:01 PM »

Hello,

Virtual COM port (VCP) drivers cause the USB device to appear as an additional COM port available to the PC.  Application software can access the USB device in the same way as it would access a standard COM port.

D2XX drivers allow direct access to the USB device through a DLL.  Application software can access the USB device through a series of DLL function calls.  The functions available are listed in the D2XX Programmer's Guide document which is available from the Documents section of this site.

Unfortunately you can't communicate over SPI through VCOM interface. LibMPSSE and the MPSSE Engine can only be configured via the D2XX drivers.

Best Regards,
FTDI Community
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faskrobo

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Re: What is VCOM functionality exactly?
« Reply #2 on: April 22, 2022, 03:45:19 AM »

Hello,

Virtual COM port (VCP) drivers cause the USB device to appear as an additional COM port available to the PC.  Application software can access the USB device in the same way as it would access a standard COM port.

D2XX drivers allow direct access to the USB device through a DLL.  Application software can access the USB device through a series of DLL function calls.  The functions available are listed in the D2XX Programmer's Guide document which is available from the Documents section of this site.

Unfortunately you can't communicate over SPI through VCOM interface. LibMPSSE and the MPSSE Engine can only be configured via the D2XX drivers.

Best Regards,
FTDI Community

So is VCOM only capable of controlling UART transfers then (i.e. no bit-banging or other interfacing)?
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Re: What is VCOM functionality exactly?
« Reply #3 on: April 22, 2022, 11:56:50 AM »

Hello,

Yes that is correct. Bit bang operation also requires the D2XX driver.

Best Regards,
FTDI Community
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matioss

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Re: What is VCOM functionality exactly?
« Reply #4 on: October 13, 2022, 11:13:23 AM »

Hello

I am looking for solutions to the problem of non-programming VNC2 chip(I am use VNC2-48 Development Module). When I was in
FLASH ROM window, I choose Chip to VNC2, Programming Interface to UART and Com Port to COM4 and I choose Baud rate to the lowest number 115200. I choose this because I use my own usb to uart bridge support to 1Mb baudrate, I don't use TTL-232R-3V3 Cable . When I Click on program,  status bellow image of folder write that  device is correct and after this FT_Prog try to set baud rate and after this ouer program FT_Prog freezes and finnalny I don't lode rom file to my developer board.


Please Help me!!!!!!!!!!!!
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Re: What is VCOM functionality exactly?
« Reply #5 on: October 14, 2022, 03:52:34 PM »

Hello,

Which VNC2-48 Development Module and USB to UART bridge are you using exactly?

Please see AN_159 Vinculum-II Firmware Flash Programming which should help you.

Note that when programming VNC2 via UART, to enable bootloader mode, the PROG# pin must be driven low and VNC2 must
then be reset by driving the RESET# pin low then high.

I have tested this here and it works as expected:



Best Regards,
FTDI Community
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matioss

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Re: What is VCOM functionality exactly?
« Reply #6 on: October 26, 2022, 07:00:04 AM »

Hello,

Which VNC2-48 Development Module and USB to UART bridge are you using exactly?

Please see AN_159 Vinculum-II Firmware Flash Programming which should help you.

Note that when programming VNC2 via UART, to enable bootloader mode, the PROG# pin must be driven low and VNC2 must
then be reset by driving the RESET# pin low then high.

I have tested this here and it works as expected:



Best Regards,
FTDI Community

Hi, I am using vnc2-48L1C and I am using ft232RL to program VNC2 via usb
« Last Edit: October 26, 2022, 07:32:35 AM by matioss »
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Re: What is VCOM functionality exactly?
« Reply #7 on: October 27, 2022, 03:37:53 PM »

Hello,

Please check your hardware connections according to the application note.

TXD/RXD/CTS/RTS signals are required. Note that these signals should be cross connected.

Also ensure PROG# is connected GND on the VNC2 prior to applying power to the device.

I would also advice purchasing TTL-232R-3V3 cable which is recommended.

Best Regards,
FTDI Community
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