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NEXYS 3, PMOD TMP2, PMOD NIC 100 Interfacing


SHASHANKPANDE

Question

Hii..

 

           I am presently working on NEXYS 3 FPGA board and trying to interface the PMOD TMP2 and PMOD NIC 100, I have completed programming for those modules, but while actually interfacing them I am facing a problem as to

 

1. HOW AND FROM WHICH PIN CAN I  APPLY AN EXTERNAL CLOCK TO THE NEXYS 3 KIT  ??

 

2. ALSO THE PMOD PINOUTS FROM JA1 TO JD10 ON MY BOARD CANT BE ALLOTED TO THE PMOD TMP2 and PMOD NIC 100 MODULE INPUTS IN XILINX PLAN AHEAD, IF I ASSIGN THEM ON THE SOFTWARE THEN WHILE ACTUALLY CHECKING THE WORKING THERE IS NO OUTPUT..!!

I AM USING Xilinx ISE Design Suite 12.4

 

HOW CAN THIS PROBLEM BE RESOLVED..KINDLY HELP...!!

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6 answers to this question

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Sorry I missed your first question: you should be able to connect a 3.3V oscillator to a pmod pin that is connected to GCLK input of the FPGA. These can be seen in the schematic. JC1 and JB10 are a couple that would work for example. BTW, the Nexys3 has A LOT of internal clocking resources that can create all sorts of frequencies and phase relationships from the onboard 100 MHz reference oscillator... will this not work for generating the frequency you need?

 

As for the UCF, it looks like your pins are not being LOCed correctly. For example, lets look at the TMP2 constraints: If the TMP2 were connected to JA, then SCL should be LOCed to N10 and SDA should be LOCed to P11. Assuming clk is the 100MHz reference clock, it should be LOCed to V10. You have these pins all connected to push buttons for some reason...

 

I recommend you just use the Master Nexys3 UCF for your design. It is found on this page: http://www.digilentinc.com/Products/Detail.cfm?NavPath=2,400,897&Prod=NEXYS3. Just uncomment the pins of the Pmods you will be using and rename the appropriate NET names to match your top level net names. 

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Thanks for your support....
 
Following is the UCF file for PMOD NIC 100 i.e. RS 232 protocol
 
# PlanAhead Generated physical constraints 
 
NET "clk" LOC = T10;
NET "tx" LOC = U16;
 
& the following is for PMODTMP2 i.e. I2C protocol
 
#PACE: Start of Constraints generated by PACE
 
#PACE: Start of PACE I/O Pin Assignments
#NET "clk"  LOC = "p50"  ;
#NET "reg<0>"  LOC = "p86"  ;
#NET "reg<1>"  LOC = "p85"  ;
#NET "reg<2>"  LOC = "p82"  ;
#NET "reg<3>"  LOC = "p81"  ;
#NET "reg<4>"  LOC = "p79"  ;
#NET "reg<5>"  LOC = "p78"  ;
#NET "reg<6>"  LOC = "p77"  ;
#NET "reg<7>"  LOC = "p76"  ;
#NET "SCL"  LOC = "p41"  ;
#NET "SDA"  LOC = "p42"  ;
 
#PACE: Start of PACE Area Constraints
 
#PACE: Start of PACE Prohibit Constraints
 
#PACE: End of Constraints generated by PACE
 
 
NET "SCL" LOC = C4;
NET "SDA" LOC = C9;
NET "clk" LOC = D9;
NET "reg[0]" LOC = U16;
NET "reg[1]" LOC = V16;
NET "reg[2]" LOC = U15;
NET "reg[3]" LOC = V15;
NET "reg[4]" LOC = M11;
NET "reg[5]" LOC = N11;
NET "reg[6]" LOC = R11;
NET "reg[7]" LOC = T11;
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Thank You so much for the help...!!

 

I tried to edit it as you said and it worked the PMOD TMP2 is now working..!!

 

I am a beginner and I am facing a problem with PMOD NIC 100, as to which protocol should be used..??

 

Can I use RS232..??..or any other is used to interface it..??..I simply need to interface it with my computer for data transfer of PMOD TMP2

 

Please Help...

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Hi,

 

The PmodNIC100 uses the SPI protocol to interface with the Nexys 3. I'm personally not familiar with FPGAs and the Pmod uses an ethernet controller from Microchip, so the associated libraries on its product page are designed for a microcontroller interface, but it may be able to help you get started.

 

Let me know if you have any more questions.

 

Thanks,

JColvin

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