how many EMIOs can be redefined in low speed 40-pin expansion connector

Question

Hi,

I plan to design own mezzanine card that connect to 40pin expansion connector. There will be 20 IOs defined and used by FPGA side in my design. I can find 12 HD_GPIOs that can be used freely according to the schematics.

Regarding the left 8 IOs, can I redefine those MIOs as EMIOs and programmed by PL side?

Or I have to consider connect the card to 60pins' connector.

bhfletcher · Answer

PL I/Os are mostly universal in that they can connect to IP in the PL or via EMIO to the PS (with a few exceptions).

PS MIO can only be connected to the PS. A limited set of valid pinouts are available in the TRM.

The LS expansion has 16 PL I/Os (not 12), labeled HD_GPIO[0:15]. These come from Bank 26 with an I/O voltage of 3.3V. Note that there is an error in v1.2 of the UG that I just spotted in Table 7. Anything connected to REFDES J5 is the Low Speed Expansion Connector (UG shows them as High Speed).

The HS expansion has a total of 30 PL I/Os, but you have to be careful looking at the I/O voltages.

2 PL I/Os on Bank 26 (3.3V)
27 PL I/Os on Bank 65 (1.2V)
1 PL I/O on Bank 66 (1.2V)

What I/O voltage are you able to handle for your 20 I/Os? I think the HS expansion is your best option, giving you 20 I/Os all the same bank.

Bryan

zf2021 · Answer

"These come from Bank 26 with an I/O voltage of 3.3V"

-> It seems it's different from the schematics in which the power of Bank 26 is VCCAUX=1.8V. and the voltage value I measured on the board is 1.8V as well.

the module type in my hand is 'AES-ULTRA96-V2-G'.

"What I/O voltage are you able to handle for your 20 I/Os?"

->3.3V is the prefered voltage level for my design. Now I have to consider adding level shift circuit to shift 1.2v or 1.8v signals to 3.3v. the higher level of input, the shorter propogation delay time while shifting.

bhfletcher · Answer

Schematic is always a better resource than the UG, just not as easy to read. You are correct that Bank 26 VCCO is VCCAUX = 1.8V. I have another correction to make in the UG, so thanks for uncovering that!

So it looks like neither HS or LS will give you the voltage you want. If you are looking at voltage translation for either, then the HS expansion at least gives you the number of I/Os that you want.

If this is a serious problem, you could look at Avnet's UltraZed-EG SK. That comes with the I/O Carrier that has an Arduino Shield expansion with 22 PL I/Os at 3.3V.

http://avnet.me/ultrazed-eg

Bryan

bhfletcher · Answer

I have made the LS Expansion Bank 26 voltage corrections in an updated UG. Ultra96-V2-HW-User-Guide-v1_3.pdf Thanks again for your feedback! Bryan

how many EMIOs can be redefined in low speed 40-pin expansion connector

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