From 432de7d2c839a713f6662824fc6a4e92e8cee9dc Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?King=20K=C3=A9vin?= Date: Wed, 22 Jun 2022 14:27:49 +0200 Subject: [PATCH] doc: move limitions higher --- README.md | 30 +++++++++++++++--------------- 1 file changed, 15 insertions(+), 15 deletions(-) diff --git a/README.md b/README.md index 878c596..1a09b0b 100644 --- a/README.md +++ b/README.md @@ -43,6 +43,21 @@ By default, the 5V supplied by the device is forwarded to the monitor. To further reduce the attack surface, you can disable this by cutting the trace between the two pads marked 5V. The risk is that some monitors rely on this signal to detect when a device is plugged in. +limitations +=========== + +High-bandwidth Digital Content Protection (HDCP) is not supported since the DDC interface is limited to the EDID information. + +mode of operation +================= + +To protect the monitor, the HDMI firewall only forwards the signal lines used for audio/video (A/V) data transfer (D0, D1, D2, CK). +All other signal lines are unconnected (CEC, SDA, SCL, utility/HEAC+, HPD). +This will block all non A/V interfaces (e.g. DDC, HPD, CEC, HEAC, MHL) +The SDA/SCL lines used for the DDC interface to provide the EDID information to the device are connected to an EEPROM on the firewall. +This is where you need to copy the monitor information to. +This limits the DDC interface to the EDID information. + installation ============ @@ -331,18 +346,3 @@ To verify of the data has been written correctly, read it back: ~~~ sudo ./edid-rw 4 | edid-decode ~~~ - -limitations -=========== - -High-bandwidth Digital Content Protection (HDCP) is not supported since the DDC interface is limited to the EDID information. - -mode of operation -================= - -To protect the monitor, the HDMI firewall only forwards the signal lines used for audio/video (A/V) data transfer (D0, D1, D2, CK). -All other signal lines are unconnected (CEC, SDA, SCL, utility/HEAC+, HPD). -This will block all non A/V interfaces (e.g. DDC, HPD, CEC, HEAC, MHL) -The SDA/SCL lines used for the DDC interface to provide the EDID information to the device are connected to an EEPROM on the firewall. -This is where you need to copy the monitor information to. -This limits the DDC interface to the EDID information.