Author Topic: TE0820 system device tree question on test_board reference design  (Read 429 times)

DR

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Hello Everyone,

I have been working with the test_board reference design for the TE0820 for a few weeks now
Using Vivado 2021.2 and Petalinux 2021.2

Ran into a couple questions about the system device tree in "system-user.dtsi"

1) For the SD0 eMMC entry, I see:
              // disable-wp
    which implies that the write protect is not disabled - However I am able to format and wrote to the eMMC device.
    How is this possible?

2) The SD0 eMMC entry also shows:
            no-1-8-v
    Again, this implies that the eMMC should be running at 3.3V. However, when I look at the schematic, I see it is connected to Bank 500 which is a 1.8V bank
    Also - the SDINBDG4-8G NAND chip uses 1.8V for VCCQ
    I would like to understand why the SD0 eMMC entry is set for no-1-8-v?

3) The SD1 sd2.0 entry shows no-1-8-v, which makes sense, since this SDIO bus is on BANK 501 and 3.3V
    However, the TE0701 uses a voltage translator U2 from 1.8v to 3.3v running from VIOB which is 1.8v on JM1
    I don't understand how the voltage translator could be working? i.e. the FPGA side will be getting 1.8v from the translator?

Thank you for your help.
Dave

JH

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Re: TE0820 system device tree question on test_board reference design
« Reply #1 on: May 04, 2022, 07:13:17 AM »
Hi,
Quote
1) For the SD0 eMMC entry, I see:
              // disable-wp
    which implies that the write protect is not disabled - However I am able to format and wrote to the eMMC device.
    How is this possible?
That's a question to xilinx :-)
Maybe this will be ignored. Did you translate final dtb back dts and check if it was add there?
Quote
2) The SD0 eMMC entry also shows:
            no-1-8-v
    Again, this implies that the eMMC should be running at 3.3V. However, when I look at the schematic, I see it is connected to Bank 500 which is a 1.8V bank
    Also - the SDINBDG4-8G NAND chip uses 1.8V for VCCQ
    I would like to understand why the SD0 eMMC entry is set for no-1-8-v?
In the past some customer has detected sometime linux access problem and this property has solved this(I don't know why)....maybe it's not longer needed.
Quote
The SD1 sd2.0 entry shows no-1-8-v, which makes sense, since this SDIO bus is on BANK 501 and 3.3V
    However, the TE0701 uses a voltage translator U2 from 1.8v to 3.3v running from VIOB which is 1.8v on JM1
    I don't understand how the voltage translator could be working? i.e. the FPGA side will be getting 1.8v from the translator?
See note:https://wiki.trenz-electronic.de/display/PD/4+x+5+SoM+Carriers#id-4x5SoMCarriers-TE0701
TE0701 was original design for our 7 series Zynq module which use 1.8V. On the next PCB update it's planned to add jumper for voltage selection...
br
John