Electronics > FPGA

Tang Nano 1K (Gowin FPGA) VGA output - artefacts, sync problem

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vstrakh:
I'm using Seeedstudio's "5 inch TFT display for tang nano".
I do have 16-bit all-ones to all-zeros switching at 28 MHz pixel clock (800x480 @ 50 Hz) in the onboard FPC connector with no issues whatsoever, so the fpga power should have nothing to do with it.

Sure that display has synchronous interface and some analog noise might be hidden, but it couldn't hide strong effects that can cause the loss of the sync.
The flat cable to the TFT has no ground plane directly between the edge of the cable and up until the lcd controller's power circuitry (like maybe ~2 cm), and I can't tell if there is a ground plane under the traces between fpga and FPC connector. I see all the traces between fpga and FPC on top and bottom sides, but that doesn't tell if pcb is 2 or 4 layers.

up8051:
I have two additional problems :

1.
I cannot program the embfFlash memory with the programmer  version 1.9.8 build 8004
I always get error:

Info:   Status Code: 0x00015421
Error:   Finished, NOT wakes up
Info:   User Code: 0x00000000

RAM is programmed without problems.

I can program without problem by very old programmer version   "Programmer 2 Beta.100330

The cable settings (2MHz) are the same for both programmers.

2.
Sometimes, when the chip is powered up, the FPGA does not start.
I have to disconnect the power and turn it on again.

Any advice?

Regards
JarekC

vstrakh:

--- Quote from: up8051 on January 09, 2022, 01:02:08 pm ---The cable settings (2MHz) are the same for both programmers.

--- End quote ---

Set it to 2.5MHz.
Apparently 2MHz is not universally compatible, I had issues with it too.

up8051:
I tried 2.5MHz but without succes.

up8051:
I installed newest version 1.9.8.01 build 10027 but the same problem. |O

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