[sdiy] Does usb c alternative mode allow analog signals on the multi-purpose pins?

[Mike Bryant]

Pin 1 : PCIE_CLK_nREQ
Pin 2 : PCIE_CLK_N
Pin 3 : PCIE_CLK_P
Pin 4 : PCIE_nRST
Pin 5 : PCIE_TX_N
Pin 6 : PCIE_TX_P
Pin 7 : GND
Pin 8 : PCIE_RX_N
Pin 9 : PCIE_RX_P

_P and _N pins can be swapped if easier - makes no difference to the decoded data

________________________________
From: Didrik Madheden <nitro2k01 at gmail.com>
Sent: 18 November 2022 00:39
To: Mike Bryant <mbryant at futurehorizons.com>
Cc: synth-diy <synth-diy at synth-diy.org>
Subject: Re: [sdiy] Does usb c alternative mode allow analog signals on the multi-purpose pins?

Hmm. On that note, how are those wired? There are pins reserved for two rx and two tx differential pairs, which are somewhat protocol agnostic. Those can be used for PCIe within the USB 3 standard, or to transfer video data. Whether any given adapter is fully standards compliant is a different issue, but those would be logical pins to use. Or do those adapters use other pins for PCIe lanes as well like USB2 D+ and D- or CC/SBU?

/Didrik

On Tue, 15 Nov 2022, 23:42 Mike Bryant, <mbryant at futurehorizons.com<mailto:mbryant at futurehorizons.com>> wrote:
Well that was effective then ... NOT :-)

All the Chinese vendors have now agreed on a standard wiring for PCIe extension over the USB-C cable.

________________________________
From: Synth-diy <synth-diy-bounces at synth-diy.org<mailto:synth-diy-bounces at synth-diy.org>> on behalf of Chromatest J. Pantsmaker via Synth-diy <synth-diy at synth-diy.org<mailto:synth-diy at synth-diy.org>>
Sent: 15 November 2022 20:23
To: cheater cheater <cheater00social at gmail.com<mailto:cheater00social at gmail.com>>
Cc: synth-diy <synth-diy at synth-diy.org<mailto:synth-diy at synth-diy.org>>
Subject: Re: [sdiy] Does usb c alternative mode allow analog signals on the multi-purpose pins?

"NOTE: Adopters may only use the USB Type-C® cable and connector to implement USB or third party functionality as expressly described in this Specification; all other uses are prohibited."
From:
https://www.usb.org/sites/default/files/USB%20Type-C%20Spec%20R2.0%20-%20August%202019.pdf


On Tue, Nov 15, 2022 at 11:08 AM cheater cheater via Synth-diy <synth-diy at synth-diy.org<mailto:synth-diy at synth-diy.org>> wrote:
As in subject. Is there anything in the spec that speaks against this?
Where would one go in order to get a definitive answer to this?
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