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sipeed / TangNano-9K-example

TangNano-9K-example project
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picotiny example doesn't show up via HDMI capture #6

Open jeremyherbert opened 2 years ago

jeremyherbert commented 2 years ago

Hi,

I have successfully flashed the picotiny example to the Tang Nano 9K and it works on my LCD monitor via HDMI. However, when I connect it to a HDMI capture device, the HDMI video is not detected. I have tried the Elgato Cam Link 4K as well as a generic USB HDMI capture device that you can buy on ebay/aliexpress: https://www.adafruit.com/product/4669 - in both cases I just get a black screen, and the status LED on the Cam Link indicates that there is no HDMI detected.

I have previously used these capture devices with the ULX3S ECP5-based dev kit, so I know they work with some form of HDMI from FPGAs.

Has this example been tested on a HDMI capture device? I also tried the Martoni HdmiCore code, but it gives the same result: https://github.com/Martoni/HdmiCore/issues/7

scpcom commented 2 years ago

I can confirm this limitation:

nekomona commented 2 years ago

Have just tested Tang Nano 9K on a cheapo, possibly MS2109-based USB 2.0 UVC capturer with several random HDMI cables around me and the picotiny example worked fine with all of them (apart from the horrendous image quality after MJPEG compression).

It could be some dev board - cable - adapter combinations that fails the signal requirement at the physical level. Sadly I have little idea of what can be done with it. ╥﹏╥

hvegh commented 2 years ago

When i plug the Tang Nano 9K in port 1 (HDMI) no screen, but if i use port 2 on the TV (HDMI/DVI) output is shown.. Seems like picotiny does not implement HDMI fully yet, more like DVI for now..

jaseg commented 1 year ago

I got it to work without issues on both an older Dell monitor and on one of these fake USB 3.0 HDMI/USB UVC converters. Mine self-identifies as some unspecified "macrosilicon" product. One thing that tripped me up for a bit is that the HDMI socket on the board is rather tight, and plugging in a HDMI cable for the first time takes some force.

hvegh commented 1 year ago

The issue is resolved, the TangNano has AC coupled HDMI, while most computer based monitors seem to accept this. TV sets use open-drain HDMI inputs, which need conversion electronics to operate. See https://www.eevblog.com/forum/fpga/fpga-to-hdmi-variants/

andryblack commented 1 year ago

On my board not soldered R1 jumper (see schematic) after connect pads my tv detect signal and show picture.