SN75DP159: The device can not transfer image to some displayers when the input signal comes from Mac Mini

Hi,

I would take a look at the HPD snoop and DDC snoop implementation between the DP149 and the DP159 EVM.

DP149 EVM

2.5.1 HPD Snoop Option

To accommodate systems that do not properly resend DDC commands after HPD goes low, an HPD snoop mode option is implemented on the DP149RSBEVM. This mode allows the HPD line to be routed around the DP149, but remain connected to the DP149 on the sink side to allow the DP149 to snoop its state. This snoop mode is disabled by default on the DP149RSBEVMs.

• Pop R131, no pop R129, R130, R139 for HPD on

• No pop R131, pop R129, R130, R139 for HPD snoop only.

2.5.2 DDC Snoop Option

To accommodate systems that do not properly support clock stretching on the DDC lines, we have implemented a snoop mode on the DP149RSBEVM. This mode allows the DDC lines to be routed around the DP149RSB, but remain connected to the DP149RSB on the sink side to allow the DP149RSB to snoop the DDC traffic. This snoop mode is disabled by default on the DP149RSBEVMs. Please note that snoop mode will connect the 3.3-V DDC lines on the DP interface to the 5.0-V DDC lines of the HDMI interface. Only enable this mode if the DP source can accept 5-V DDC signaling.

• Pop R28, R29, R31, R32. No pop R126, R136, R140, R141- DP149RSB, DDC on

• Pop R126, R136, R140, R141. No pop R28, R29, R31, R32 – DP149RSB, DDC snoop only

DP159RGZ EVM

2.5.1 HPD Snoop Option

To accommodate systems that do not properly resend DDC commands after HPD goes low, we have implemented a HPD snoop mode on the DP159RGZEVM. This mode allows the HPD line to be routed around the DP159, but remain connected to the DP159 on the sink side to allow the DP159 to snoop its state. This snoop mode is disabled by default on the DP159RGZEVMs.

• Pop R131, no pop R129, R130, R139 for HPD on

• No pop R131, pop R129, R130, R139 for HPD snoop only

2.5.2 DDC Snoop Option – not Available for DP159RGZ REV B To accommodate systems that do not properly support clock stretching on the DDC lines, we have implemented a snoop mode on the DP159RGZEVM. This mode allows the DDC lines to be routed around the DP159RGZ, but remain connected to the DP159RGZ on the sink side to allow the DP159RGZ to snoop the DDC traffic. This snoop mode is enabled by default on the DP159RGZ REV B1 EVMs.

• Pop R126, R125, R132, R133. No pop R31, R32 – DP159RGZ, DDC snoop only

• Pop R31, R32. No pop R126, R125, R132, R133 – DP159RGZ, DDC on

For the difference between the DP159 RGZ and RSB, Please see the Pin Functions table in the datasheet. There is also a schematic checklist you can reference in the Technical Documents section of the product folder.

I sent you the DP159RGZ EVM board file in a private message, please check.

Thanks

David

Hi David：

Our DemoBoard is RGZ 48pin，as last email said， 1.Cannot display the image after replugging the cable 2. LED D2 will light up when power is on .3 HDMI access to EVM, HPD_ SNK is raised, the voltage is: 4.98v, 4.R31, R32 is with patch, R125, R126, R132, R133 are NC State (default)                   Test platform：MAC mini OS:os x yosemite 10.10 ，Monitor：AOC2790R3B 4K60HZ,Hisense TV HZ55A65E 4K60HZ, Samsung LS27R75 2K 144HZ

 Today's debugging found: 1. Connect three display devices can not light up, connect another HDMI input port of the MAC mini box to the monitor. It is found that the device can be recognized and the correct EDID is read, but the resolution will be set to 4k60hz by default. If you manually change it to 4k30hz, you can turn on Hisense when you unplug the monitor. If you connect the Samsung display, you will set it to 144hz by default. In the same way, you can change it to 60Hz. The display is normal. AOC verification is invalid Only when the monitor is connected can it be turned on.

Note: the output port of Mac mini box is two mini DP + HDMI. If you have tried to connect the monitor directly, the maximum is 4k30hz

Questions: 1. Why is the refresh rate higher than the output of the device through sn75dp159 (no problem with EDID reading); 2. Demoboard J7 HDMI on AOC display_ SET_ TEST_ When A1 is set to 2-3pin DVI mode, the resolution is 1080p. 3. Try to access the monitor on Philips Phl 328p6vu 4k60hz monitor and modify the refresh rate to 4k30hz, it can not be turned on (the same as the second point DVI mode can light 1080p). However, the environment above sn75dp149 and connected to the monitor are normal, so it is not necessary to modify the refresh frequency.

1.Attached is a schematic diagram of our SN75DP149. no problem. Check the data sheet and found that it is pin-to-pin with SN75DP159. The problem still exists after replacing the IC. Please help us see how to modify this diagram to solve the compatibility problem of SN75DP159

2.If information can , can you come to our company for debugging.DP TO HDMI_M V1.0.pdf

Hi,

Looking at the DP149 schematic.

1. You are using the downstream DP connector pinout when you should be using the upstream DP connector, so the lane order is not correct. Are you enabling the lane swap feature in the DP149? Otherwise I don't see how DP149 will work with the current lane order.

2. I would also implement the DDC snoop mode, please refer to the DP159 EVM schematic for DDC snoop implementation.

Questions: 1. Why is the refresh rate higher than the output of the device through sn75dp159 (no problem with EDID reading);

Does the MAC Mini supports HDMI2.0 at its output? If it supports HDMI2.0(4k@60Hz) but downgrade to HDMI1.4(4k@30Hz), it could be a signal integrity issue which the DP159 helped to clean it up.

Thanks

David