Override IFC_TE strap

[scottgerhold]

I have IFC_TE strapped incorrectly for the location of the Boot flash. The board is designed to boot RCW/PBI from SPI and then load boot code from NOR flash on CS0. The NOR flash is on the fast side of the IFC subsystem. The transceiver is active when IFC_TE is low.

My problem is that if I pull IFC_TE low to make the T2080 operate as desired for NOR on the fast side, then the transceiver is enabled and will mess with the LAD lines providing the strapping (if IFC_BCTL is also low). Thus I seem to be stuck in a bad spot.

Can you tell me (I will verify in the lab shortly) if IFC_BCTL is high or lower during PORESET assertion?

I was thinking I could leave IFC_TE strapped high as I have it to leave the transceiver off and then use the PBL to change CSPR0[TE]. But that doesn't appear like it will work as at the end of PBL the T2080 will write over CSPR0 anyway and cancel whatever I would have changed. Is that correct - that any changes I make to CSPR0 will be wiped out when the PBL is done loading (even though it isn't loading PBL from NOR, but rather from SPI). (section 5.4.8.3 of T2080 Ref Man). 

[ufedor]

IFC_BCTL is high when PORESET_B is asserted.

[scottgerhold]

The scope plot I captured doesn't agree with your statement. At the very

instant the PORESET goes high BCTL was also going high. So it seems BCTL

goes high in response to PORESET going high. In looking at the schematic in

the T2080PCIe_SCH1202.pdf it has a 4.7k pullup to 3.3V on it (which seems

wrong as the IFC interface is 1.8V). See picture below. In the QDS it

appears that BCTL doesn't have any discrete pullups, but without looking

into the FPGA (U145 - A3PE1500) is it possible you had a pull-up assigned

in that device. I do not have BCTL connected to anything except the T2080

and 2 FXLH42245 buffers (into the T/R# pins).

Here is the waveform I measured on my board during power up. The particular

waveform I captured happened to be one that apparently saw a bad cfg_rcw

value and generated a RESET_REQ (we named it PPC_FATAL). So you can

actually see PORESET transition low again and notice the decay from

IFC_BCTL being high slowly going low. It really appears that IFC_BCTL is

not driven during PORESET being low. I will attempt to put a pull-up on it,

but being low is acceptable - I just need to understand what it really is.

The datasheet implies that it is a driven output and I find nothing that

tells me I should have a pull-up or pull-down on it. (sorry for the yellow

color on the trace).

*Scott Gerhold *

Principal Electrical Engineer | Avionics

COLLINS AEROSPACE

MS 130-106, 400 Collins Rd NE, Cedar Rapids, IA 52405, USA

Tel: +1 319 295 4866 [

scott.gerhold@collins.com <scott.gerhold@collins.com> | *collinsaerospace.com

<http://collinsaerospace.com>*

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On Thu, Oct 31, 2019 at 1:38 PM ufedor <admin@e17311.dsca.akamaiedge.net>

[ufedor]

You wrote:

> decay from IFC_BCTL being high slowly going low.

> It really appears that IFC_BCTL is not driven during PORESET being low.

Excuse me, but in the provided schematics picture the IFC_BCTL as CFG_IO_PORTS2 has 4.7 kOhm pull-up.

Is the pull-up really connected?

[scottgerhold]

I cannot tell you if the resistor is really connected. The schematic I

copied it from was a Freescale schematic provided for the T2080PCIe board

dated 12-2013. I only included it in the discussion as I wasn't sure if you

were probing the signal on one of your test cards.

*Scott Gerhold *

Principal Electrical Engineer | Avionics

COLLINS AEROSPACE

MS 130-106, 400 Collins Rd NE, Cedar Rapids, IA 52405, USA

Tel: +1 319 295 4866 [

scott.gerhold@collins.com <scott.gerhold@collins.com> | *collinsaerospace.com

<http://collinsaerospace.com>*

CONFIDENTIALITY WARNING: This message may contain proprietary and/or

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On Mon, Nov 4, 2019 at 10:38 PM ufedor <admin@e17311.dsca.akamaiedge.net>

[ufedor]

> I cannot tell you if the resistor is really connected.

Do you mean that IFC_BCTL is not pulled up or down on your board?

[scottgerhold]

On my board there is not a pullup or pulldown resistor at this time.

*Scott Gerhold *

Principal Electrical Engineer | Avionics

COLLINS AEROSPACE

MS 130-106, 400 Collins Rd NE, Cedar Rapids, IA 52405, USA

Tel: +1 319 295 4866 [

scott.gerhold@collins.com <scott.gerhold@collins.com> | *collinsaerospace.com

<http://collinsaerospace.com>*

CONFIDENTIALITY WARNING: This message may contain proprietary and/or

privileged information of Collins Aerospace and its affiliated companies.

If you are not the intended recipient, please 1) Do not disclose, copy,

distribute or use this message or its contents. 2) Advise the sender by

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On Tue, Nov 5, 2019 at 9:22 AM ufedor <admin@e17311.dsca.akamaiedge.net>