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vs.rishi
Contributor
Contributor
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Registered: ‎11-23-2012

interfacing problem

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hi 

i read kcpsm3 manual.now i'm trying to checkout the reference uart design given in the zip file but it seems like my pc did not have serial ports..is there any software to create virtual serial ports or anyother way i can do it?should i buy usb to serial converter cable for this and future designs?BTW my board is basys2

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chapman
Xilinx Employee
Xilinx Employee
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Registered: ‎09-05-2007

You really need to explain EXACTLY how it is you have connected your Basys2 Board to your PC. As far as I can see from the ‘Digilent Basys2 Board Reference Manual’ the board does not have an RS232 serial port or a USB/UART interface. So what are you connecting to your PC and how?

Ken Chapman
Principal Engineer, Xilinx UK

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eilert
Teacher
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Registered: ‎08-14-2007

Hi,

yes, an USB-Serial converter would help.

Actual boards (ATLYS, NEXYS3) have these on board already.

 

But the BASYS2 Board has no RS232 level converter.

Or do you have some PMOD for that purpose?

 

 

 

Have a nice synthesis

  Eilert

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vs.rishi
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Contributor
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Registered: ‎11-23-2012

Thank you, I have old PC which have a serial port.Now  problem is basys2 has a silicon oscillator,clock is 50MHz  I saw in manual the clock for this design is 55MHz so I instantiated DCM and used 55MHz clock.Is there anything I need to take care of because still I am unable to communicate..

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chapman
Xilinx Employee
Xilinx Employee
12,625 Views
Registered: ‎09-05-2007

You really need to explain EXACTLY how it is you have connected your Basys2 Board to your PC. As far as I can see from the ‘Digilent Basys2 Board Reference Manual’ the board does not have an RS232 serial port or a USB/UART interface. So what are you connecting to your PC and how?

Ken Chapman
Principal Engineer, Xilinx UK

View solution in original post

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vs.rishi
Contributor
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Registered: ‎11-23-2012

thank you,

i was mistaken.i felt i can use power cable for serial communication because he stated programming/data transfers.so is power cable used to transfer bit files or it perfoms anyother job?

 

 

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vs.rishi
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Registered: ‎11-23-2012
 
cable.PNG
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eilert
Teacher
Teacher
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Registered: ‎08-14-2007

Hi,

what do you know about this data interface?

The only usable software for this seems to be the Adept program from digilent.

There's some SDK available, but do you really want to write your own data transfer software and develop an appropriate hardware interface for it too?

 

Now, if you are going to use some UART in the FPGA, then you also need a suitable converter for the hardware level.

This will be at least some RS232 level converter (e.g. MAX232) or some USB-Serial converter (e.g. from FTDI).

 

It's up to you to decide which way to go,

But you have to make that decicion and tell us about your specific setup.

 

Since you mentioned that you have some old PC with a COM-Port you may think about buying/building something like this:

http://www.digilentinc.com/Products/Detail.cfm?Prod=PMOD-RS232

 

Then you just need to LOCate the UARTs external I/Os to the correct pads in the UCF file and that's it. 

 

Have a nice synthesis 

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antonis.sna
Newbie
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Registered: ‎05-23-2014
Hi,

I know that's an old post but I am very interested in connecting my Basys2 board with a PC COM port for an essay for my MSc.

I consider myself as an advanced software developer but as a total newbie in VHDL and electronical circuits.

My question is, does a tutorial or somehing like a guide exist, which will explain how to connect the Basys2 Ports (maybe PMOD connectors) with a MAX232 converter? I already have a MAX232 chip which I used in some of my RaspberryPI projects and I would like to know if I could use it with the Basys2 board too.

Thank you in advance,

Sna.
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chapman
Xilinx Employee
Xilinx Employee
8,241 Views
Registered: ‎09-05-2007

Dear Sna,

 

Each Pmod connector provides you with a simple and convenient way to access 4 I/O pins on the FPGA device as well as 2 power supply pins connecting to GND and 3.3v. Serial communication (UART) only requires two of the I/O pins so this should all be rather straightforward in terms of a hardware design. I appreciate that you are new to that but really that should be straightforward once you know the fundamentals of design.

 

The key point to note is that the Pmod connector and pins on the FPGA device are operating with 3.3v signals (LVTTL). I’m pretty sure that the MAX232 device to which you refer is a level translator. On one side it can handle the ±12v signals of the RS232 standard and on the over side it operates with a single supply rail of lower voltage. You would need to check exactly what you have but it may be a device intended to operate at 5v rather than 3.3v. Chances are it would still work at 3.3v even if it was intended to be a 5v device.

 

Having converted to the ±12v signals of RS232 you then need to connect that to your PC. A few years ago an RS232 serial port was to be found on the back of just about every PC and laptop but now they are becoming extremely rare. You can buy a USB to RS232 converter but it seems silly to go through one converter after another when you can buy a USB cable that converts directly to 3.3v signals.

 

http://www.ftdichip.com/Products/Cables/USBTTLSerial.htm

 

Note how some of these just have flying wires that you could connect straight to a Pmod connector.

 

Ken Chapman
Principal Engineer, Xilinx UK
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