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SD card support for TE0820 by carrier cards

Started by ScottBierly, January 21, 2019, 04:14:32 AM

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ScottBierly

Hello,

I have spent many hours pouring through the documentation on this SOM and the various Trenz carrier cards. In particular, I'm interested in TEO706, TEO703, and TEBA0841. Despite hours of reading on all this, I still cannot make full sense of the situation on using the SDcard. In the case of the TEO706, the cross-reference table states "(6) Works, but without carrier board modification out of specification: TE0706 SD Levelshifter powered fix by 1.8V, TE0820 SD MIO-Bank by 3.3V." This language is unclear, but I see there is a problem that on the TEO820 the SD lines are Bank 501 MIO at 3.3V, and the TE0706 has MicroSD cArd socket J4 at 3.3V (so expects 3.3V signals?) and thus the U4 device expects 1.8V from the FPGA and tries to convert them to 3.3V--I see this could be a problem. I assume in this case you could hack the board such that the 3.3V MIO lines connect directly to the J4? It might be nice to explain this all in more detail in the docs.

The TE0703 carrier seems to have the exact same situation.

The TEBA0841 on the other hand has the note "(6) Works, but without carrier board modification out of specification: TE0706 SD Levelshifter powered fix by 1.8V, TE0820 SD MIO-Bank by 3.3V.", presumably a copy and paste error? The 6 MIO lines appear to go to a 10 pin header, there is no SD socket, so presumably there is nothing actually incompatible about the SD card with this board combination if you wanted to somehow wire one up through the header?

Thank you!
Scott

JH

#1
Hello,
short answer: At the moment not a single one of our 4x5 carriers on our shop supports SD on TE0820, like it should.
Reason:
All our 4x5 carrier was designed for 7 Series SoC/FPGA, which used SD connected to 1.8V.  Carrier used level shifter from 1.8V to 3.3V. So TE0820 has SD on 3.3V MIO Bank. Carrier 1.8V for SD on B2B side and 3.3V on connector side. --> So TE0820 with any of our 4x5 carrier: 3.3V IOs drives 1.8V IOs of the carrier Levelshifter. It works, so you can boot from SD with TE0701, TE0703, TE0705 and TE0706, but it's out of the specification(1.8V vs. 3.3V).

Updates for our carriers with selectable voltage on B2B side is planned, but I can't tell you any timeline. 



Note (6) on TEBA0841 is copy paste mistake. MIOs, which are used for SD are routed to normal pinheader only, so no  SD support with TEBA0841. I will change this copy past mistake.

br
John

ScottBierly

Thanks for elaborating John. So, I think you confirmed my assumption about the mismatch (3.3V FPGA outputs connected to 1.8V inputs on the level shifter not guaranteed to work), but didn't confirm that this *could* be fixed by a physical mod (e.g., lifting pins and running wires, etc., to bypass the level shifters) on the carrier card--obviously this violates any warranty :)

That would be great to update your carriers to support your new flagship SOMs. Actually, it's kind of shocking you have these amazing Zynq Ultrascale+ modules and no great carrier for them. The existing carriers are such an eclectic mix of features, why not just make a fresh new carrier module that's small and neatly combines the basic features we need to evaluate your SOMs into one board (SD, USB, Ethernet, JTAG, UART, GPIO, something with the GT's? It's not clear why you need 5 carrier cards anyway...

On the "so no SD support with TEBA0841" comment, but isn't it the case that you did route the SD lines to the header, and therefore we could buy something like the attached adapter to add SD, and it should just work as everything is 3.3V I/O?


JH

Hi,
Quote3.3V FPGA outputs connected to 1.8V inputs on the level shifter not guaranteed to work
until now, I didn't find a module where it doesn't work. But your are right, maybe there are some special conditions where it doesn't work, i can't guarantee it.

Quote*could* be fixed by a physical mod (e.g., lifting pins and running wires, etc., to bypass the level shifters) on the carrier card
modification is possible, remove levelshifter and connect signals directly or cut the 1.8V from the levelshifter and connect this side to the 3.3V output of the carrier (Altium projects of our 4x5 carrier are free available on the download area (altium viewer is free)), or create your own carrier(this will be done in the most cases, our carrier mostly use for first test and verification).

QuoteThat would be great to update your carriers to support your new flagship SOMs. Actually, it's kind of shocking you have these amazing Zynq Ultrascale+ modules and no great carrier for them. The existing carriers are such an eclectic mix of features, why not just make a fresh new carrier module that's small and neatly combines the basic features we need to evaluate your SOMs into one board (SD, USB, Ethernet, JTAG, UART, GPIO, something with the GT's? It's not clear why you need 5 carrier cards anyway...
Switch to the TE0808/TE0807/TE0803 series there is a carrier available TEBF08080

QuoteOn the "so no SD support with TEBA0841" comment, but isn't it the case that you did route the SD lines to the header, and therefore we could buy something like the attached adapter to add SD, and it should just work as everything is 3.3V I/O?
TEB0841 was create for TE0841 and TE0741, it can be used with TE0820 but this was not the basic purpose. You can try out to connect SD Card there, but you must try out if it works or not.

br
John

ScottBierly

QuoteSwitch to the TE0808/TE0807/TE0803 series there is a carrier available TEBF08080

Ahh, well unfortunately those modules are too big to embed in my application.