Artix-7 Cmod-A7 / Arty 7 HDMI output

[davorin]

Evenin' (o;

Just got my Cmod-A7 board this week....and of course tried the design from hamsterwork driving a HDMI monitor at 1080p@60
The color bar looks  rather strange though:

http://fpga.ch/images/blog/IMG_0451.jpg

Maybe the Cmod-A7 with speed grade 1 is not up to this?

[NiHaoMike]

I'm a bit surprised you were about to get sync on a HDMI signal through a breadboard. And that's probably causing your signal integrity issues.

[davorin]

Well in the beginning the monitor didn't showed anything but the LED showed it synced to the signal...after twisting all +/- wires the display was stable ;-)

Have to dig into the original VHDL design...and probably convert it to Verilog as I am not very familiar with VHDL (I come from the electronic design).
Gonna try with just plain colours tomorrow..but this Vivado software takes takes ages to synthesize, P&R and even longer to just write a bitmap file....around 10 times it takes with Quartus...

[asmi]

1.5 Gbps lines through breadboard? Surprised it works at all.

[hamster_nz]

Impressed! I would love to know if 640x480 works well.

Based on specs an Artix7 should not do 1080p on the SelectIO pins - even on the fastest grades they are only rated at 1.25Gb/s.

[davorin]

Well it is actually based on your example design where you proofed an Artix-7 can do 1080p:

http://hamsterworks.co.nz/mediawiki/index.php/Artix_7_1080p

Why shouldn't it do 640x480 then? It is way faster than a MAX10 which can only do 800x600 TDMS or maybe 1024x768...

[hamster_nz]

I was more wondering if the picture would display without errors at 640x480 given the breadboard, wire jumpers and so on.

I couldn't get anything much better than 1024x768 to work through 0.1" pin headers, so I am surprised you get a picture at 1080p at all!

[davorin]

Well I did get a picture only after twisting the LVDS pair cables...and the 4 LVDS pairs are all on the same side...

And it still syncs after the night being powered on...but will try a 640x480 picture today...


BTW: Can't the 4 GTP transceivers be used for TDMS generation? Thought they can do 8b/10b serialization...

[davorin]

Stupid me...the Cmod-A7 35T device has only 2 GTP transceivers...but my Arty-7 board should have...

I have  HDMI output at 640x480 but with noisy pixels (whereas the same design with 800x600 on MAX10 shows no noise)...and with the sample design from the Maximator MAX10 board....so no SERDES is used and there is no option (or I don't know) how to specify the outputs as TDMS33.

[davorin]

Modified your vga code to just display grey bars from the counter register...and as it displays 7.5 bars it really seems to output 1080p@60 (o;

Sad the Cmod-A7 has too few pins laid out to the header to also have HDMI input....

[asmi]

Stupid me...the Cmod-A7 35T device has only 2 GTP transceivers...but my Arty-7 board should have...

MGTs are not broken out on that board, but even if they were, you can't use them for HDMI TX because they are electrically incompatible. You can do DisplayPort though - MGTs natively support it, and it will work super-fast.
The FPGA on Arty board doesn't have any MGTs.

[davorin]

Hmm...too bad....but at least my Arty 7 board can also do HDMI 1080p@60 on one of the two high speed PMod connectors ;-)

Have to see if the HDMI input and output together would work as well....

[asmi]

Hmm...too bad....but at least my Arty 7 board can also do HDMI 1080p@60 on one of the two high speed PMod connectors ;-)

A small hint - try using Ethernet cable instead of loose wires for wiring up your breakout. This cable contains 4 twisted pairs, so each pair needs to connect to DN+/DN- lines. It should provide higher signal integrity. I would even solder Ethernet cable directly to HDMI connector pins. Just make sure you remember which wires go where!

[davorin]

That's actually a good idea ;-)

Though I think to do a small PCB with two HDMI connectors and maybe some others.......but first had to convert the whole VHDL design into Verilog as I am more familiar with it (o;

Now let's see if I can put in my old PacMan or Zaxxon design....


BTW: Are there any affordable Artix 7 boards with GTP transceivers available for use? Maybe for testing DP?

[davorin]

This comes now close to a professional HDMI add-on PCB (o;

Now wiring the second HDMI as sink and see if I can use this board for the hamsterworks HDMI processing as well: http://hamsterworks.co.nz/mediawiki/index.php/HDMI_Processing