How to use SmartVIO Controller to change the bank VCCO to 2.5V on Eclypse Z7

[Charlie.Li]

Hi there,

I plan to design my own peripheral board attach to Eclypse Z7 with SYZYGY connector. And I am trying to generate the LVDS output through SYZYGY connector. As far as I know, all 7-series Xilinx FPGAs only support LVDS_25 I/O standard, which means the 2.5V bank VCCO is required. Moreover, I found the bank VCCO of SYZYGY connector could be select(1.2V-3.3V) by using SmartVIO Controller.

So my question is:

• Eclypse Z7 is compatible with LVDS output, am I right?
• If so, the only way to control and change the bank supplies is communicate with Eclypse PMCU by Digilent Eclypse Utility on Linux system, is that true? Because I am running Vivado on windows system and it takes time for me to explore how it works.

Thanks,

Charlie

[asmi]

Your SYZYGY daughterboard is supposed to have an MCU which would tell the main board which voltage it supports (among other things). So program that MCU such that it would report 2.5 V as the only supported voltage - and that will force SmartVIO controller to supply that voltage.

[zygot]

4 hours ago, Charlie.Li said:

Eclypse Z7 is compatible with LVDS output, am I right?

Absolutely.

And, as @asmi, alludes to your custom pod should support the SYZYGY DNA and all other standards. See Opal Kelly for information on how this works. I'd still spend some time going through the Digilent documentation. Opal Kelly's standard pods have an odd/even convention for which LVDS data pair are in/out but Xilinx is pretty flexible in this regard. Understand the Series 7 clocking and SelectIO reference guides.

There are a lot of tasty possibilities for SYZYGY.

[Charlie.Li]

Thanks for the explanation.

Does it mean no matter what kind of pod voltage(5V, 3.3V or SmartVIO ) I will use, I need to add an additional pMCU on daughter board to match SYZYGY DNA and configure the voltage? Otherwise I cannot use SYZYGY as normal FPGA I/O. 

[asmi]

1 minute ago, Charlie.Li said:

Thanks for the explanation.

Does it mean no matter what kind of pod voltage(5V, 3.3V or SmartVIO ) I will use, I need to add an additional pMCU on daughter board to match SYZYGY DNA and configure the voltage? Otherwise I cannot use SYZYGY as normal FPGA I/O. 

Yep. The spec recommends ATtiny44A MCU which is very cheap ($0.7 for single quantity).

[zygot]

SYZYGY 5V and 3.3V are fixed so the ATtiny44A mentioned by @asmihas nothing to do with them. As you suspected, in order to use any GPIO pins on your interface, you will will need to set SmartVIO properly. This requires some controller on the carrier to handle the DNA conversation. I would advise following the recommended solution for doing this.

[asmi]

Just now, zygot said:

SYZYGY 5V and 3.3V are fixed so the ATtiny44A mentioned by @asmihas nothing to do with them. 

Spec requires DNA to report current demands on each of these rails (5V, 3.3V, VIO). So I read it that you're supposed to have DNA MCU on anything you connect to SYZYGY port.

[zygot]

34 minutes ago, asmi said:

Spec requires DNA to report current demands on each of these rails (5V, 3.3V, VIO). So I read it that you're supposed to have DNA MCU on anything you connect to SYZYGY port.

Agreed.

[Charlie.Li]

Adding a MCU could be next plan for me. For some simple test, if I just want a quick test first, can I use the external power supply to power up FPGA? Apart from I2C, the SYZYGY port seems physically connect to FPGA and there is no buffer between them. Could that work if I power up FPGA from ZYZYGY Pin from daughter board.

[asmi]

17 minutes ago, Charlie.Li said:

Adding a MCU could be next plan for me. For some simple test, if I just want a quick test first, can I use the external power supply to power up FPGA? Apart from I2C, the SYZYGY port seems physically connect to FPGA and there is no buffer between them. Could that work if I power up FPGA from ZYZYGY Pin from daughter board.

I wouldn't risk it as many DC-DC converters don't like when there is a voltage on their output while they are turned off. But it's up to you really.

[zygot]

1 hour ago, Charlie.Li said:

Adding a MCU could be next plan for me

I'm not sure that I understand your intentions here but Opal Kelly sells pod breakout boards for prototyping that have the MCU onboard. This would be a good way to test out that part of your design before committing to buying PCBs.

I would think that the expense to to have a board that allows you to check your mechanical dimensions is worth buying at least one.