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MEGA65 / megaphone-r4-pcb

MEGAphone PCB redesign under NLnet Foundation grant
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HDMI is currently not showing signs of life #56

Closed goran-mahovlic closed 1 year ago

goran-mahovlic commented 2 years ago

No picture

gardners commented 2 years ago

I believe this is because the VCCIO for the appropriate bank has the wrong voltage for the Xilinx chip to do HDMI-compatible signals. We encountered this on the MEGA65 board. We might be able to work around it by using LVDS25 or some other standard that works for HDMI, but can be produced by the FPGA with its current VCCIO level.

gardners commented 1 year ago

I have had perfect HDMI output now, but it lasts for only a few minutes, and then the monitor says "no signal" and then "no cable connected". I am suspecting that the HDMI helper chip is not providing the 5V cable detection signal in some circumstances.

gardners commented 1 year ago

Confirmed that the issue is the VCC_MIC is supplying the 5V required by the HDMI helper chip. See separate issue for providing an independent supply for this purpose. Consequentially, this issue is now resolved.