• 0
Zain Zaidi

Can't figure out physical connections for Basys3 XADC Demo

Question

Hello,

Merry Christmas hope you guys are doing great. I am a beginner in digital design course and i want to implement this xadc demo project from digilentinc reference on my Basys3 FPGA. I'm having problems on the step 4 which is running the project as i can't figure the physical connections to connect to the JAXDC port on FPGA. 

image.thumb.png.c6fb2488fbd49ae91220145ae288aba1.png

 

Can someone confirm if the connections i have done in this picture are right?

image.thumb.png.e989536c21ec172b034f2983ea55dc0d.png

One last question. When you open the XADC Basys3 Demo project and see its constraints, only package pins i don't understand are these A12,B13 ones. Where are they located on FPGA? I'm assuming there are some internal connections like seven segment decoder have.

image.thumb.png.3736a10775e23c08eca92b50369d31a8.png

 

Any help appreciated. Thank You.

Regards,

Zain

 

Share this post


Link to post
Share on other sites

1 answer to this question

Recommended Posts

  • 0

Hello @Zain Zaidi,

The JAXC6 and JAXC12 provides 3.3V VCC and are not inputs.

The ADC differential input must be with a voltage difference between 0-1V.

The input signal for each JXADC channel of the Pmod must be between 0 - 3.3V.

So if you connect your XA_N channels to ground, then you must apply to the XA_P channels a voltage between 0-1V.

ex :   XA1_P= 0.5sin(wt), XA1_N = 0V   => XA1_P - XA1_N = 0.5sin(wt) differential input for ADC.

XA1_P= 2.5sin(wt), XA1_N = 2.2sin(wt)   => XA1_P - XA1_N = 0.3sin(wt) differential input for +ADC.

Please read ug480  pages 31-32.

If you look into the schematic file of the Basys 3, you will see that the Vp(A12) and Vn(B13) pins are connected to XADCGND.

 

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now