OSSC v1.6 build debugging

[krivx]

I have another thread here (https://videogameperfection.com/forums/topic/where-is-the-printf-output-routed-to/) but I should probably describe my problem rather than hinting at it.

I have a 1.6 kit assembled except for the IR receiver and Y2 (24.5 MHz crystal for the PCM1862), both parts are still in transit. Looking at the source code it I am pretty sure the OSSC should power up without these parts populated.

Instead, when I apply power:
– LCD backlight comes on but shows no text.
– Green LED lights dimly – it has only 1.8V across the limiting resistor and LED
– There is no test pattern on the HDMI port.
– All voltage regulators measure the correct output voltages and none are oscillating or rippling excessively.
– 27 MHz clock is present and looks good.
– U10 has a ~33 MHz clock signal on pin 6 (DCLK/SCK)
– U10 has spaced packets on pin 5 (ASD0/SI) 31.5ms apart
– U10 pin 1 is pulsed high every 31.5 ms
– U10 has what looks like continuous data on pin 2 (DATA0/S0). I am using the pre-programmed U10 that came with the kit, I have desoledered this and dumped it and it is not empty
– I have looked at all IC pins under a stereo microscope and resoldered by hand and with flux/hot-air and all look OK.

Any ideas? It seems as if the FPGA is attempting to load config from U10 but I can’t tell if it is successful.

[krivx]

Taking another look at the U10 dump – it doesn’t look right:

Offset(h) 00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F

00000000  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF  ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ
00000010  FF FF FF FF FF FF 7F FF FF FF FF FF FF FF FF FF  ÿÿÿÿÿÿ.ÿÿÿÿÿÿÿÿÿ
00000020  56 EF EF EF EF EF EF CF DF CF 9F 5F 1F 8F 1F 1F  VïïïïïïÏßÏŸ_....
00000030  3F 3F 3F 5F BF 5F 1F 9F DF DF 7F DF 9F BF BF BF  ???_¿_.Ÿßß.ߟ¿¿¿
00000040  1F 3F 3F 3F 3F 1F 1F 5F 5F B8 1C FF FF FF FF FF  .????..__¸.ÿÿÿÿÿ
00000050  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF  ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ
00000060  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF  ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ
00000070  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF  ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ
00000080  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF  ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ
00000090  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF  ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ
000000A0  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF  ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ
000000B0  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF  ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ
000000C0  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF  ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ
000000D0  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF  ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ
000000E0  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF  ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ
000000F0  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF  ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ
00000100  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF  ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ
00000110  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF 00  ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ.
00000120  00 00 00 04 04 04 04 04 04 04 04 04 04 04 04 04  ................
00000130  04 04 04 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
00000140  00 00 00 04 04 04 04 04 04 04 04 04 04 04 04 04  ................
00000150  04 04 04 04 04 04 04 00 00 00 00 00 00 00 00 00  ................
00000160  00 00 00 00 00 00 00 04 04 04 04 04 04 04 04 04  ................
00000170  04 04 04 04 04 04 04 04 04 04 04 00 00 00 00 00  ................
00000180  00 00 00 00 00 00 00 00 00 00 00 04 04 04 04 04  ................
00000190  04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 00  ................
000001A0  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 04  ................
000001B0  04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04  ................
000001C0  04 04 04 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
000001D0  00 00 00 04 04 04 04 04 04 04 04 04 04 04 04 04  ................
000001E0  04 04 04 04 04 04 04 00 00 00 00 00 00 00 00 00  ................
000001F0  00 00 00 00 00 00 00 04 04 04 04 04 04 04 04 04  ................
00000200  04 04 04 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
00000210  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 04  ................
00000220  04 04 04 04 04 04 04 00 00 00 00 00 00 00 00 00  ................
00000230  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
00000240  00 00 00 04 04 04 04 04 04 04 04 04 04 04 04 00  ................
00000250  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
00000260  00 00 00 04 04 04 04 00 00 00 00 00 00 00 00 00  ................
00000270  00 00 00 04 04 04 04 00 00 00 00 00 00 00 00 00  ................
00000280  00 00 00 00 00 00 00 00 00 00 00 04 04 04 04 04  ................
00000290  04 04 04 04 04 04 04 04 04 04 04 00 00 00 00 00  ................
000002A0  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 04  ................
000002B0  04 04 04 04 04 04 04 04 04 04 04 04 04 04 04     ...............

Is there a file available I can use to program this chip? I assume the SD card update file is similar but has some kind of header applied to it?

[krivx]

A binary compare of my dumped image and the files at https://www.niksula.hut.fi/~mhiienka/ossc/fw/ show that there is a 512 byte header added. Looks like U10 has valid data, just not the most up to date version.

[Morpheus_79]

I’ve had a similar behavior after building the 1.5 kit: after powering up the OSSC the green LED and the LCD backlight lit up, but then the backlight got dim and nothing else happened. No text on the LCD, no HDMI output – nothing. However the FPGA seemed to work, since i was able to flash the latest firmware via USB blaster after powering the OSSC up for the first time. But that didn’t change anything.

The culprit was a solder bridge on two pins of the TVP7002 (pin 79 & 80 if i remember correctly). Hadn’t seen it under the microscope, but measured it after painstakingly testing all adjacent pins on all ICs for continuity. Maybe in your case the problem is kind of the the same?

[krivx]

I’ll take another look under higher magnification, I think a reflowing/resoldering would catch a bridge like that though. Thanks.

Do you know if something as simple as a missing PCM1862 crystal or IR receiver would cause this?

[Morpheus_79]

A missing IR receiver couldn’t cause it – i know that for sure, because it was out of stock and therefore my OSSC 1.5 didn’t have one at first. And i don’t believe the missing crystal would cause that either, because i had a solder bridge on the two pins of the very same crystal on my OSSC 1.6 and it just prevented the OSSC from outputting digital audio – everything else worked fine.

Did you solder the FPGA and the TVP7002 to the big grounding pads, or did you only solder the pins of both ICs to the pcb? I’m just asking, because i remember vaguely reading somewhere, that someone had (kind of similar) problems with his OSSC… till someone else he gave the OSSC to find the cause figured out, that not soldering the ICs to the grounding pads had caused the issue. I don’t know for sure, if that REALLY was the source of the problem (cause desoldering and resoldering both ICs may have fixed something else), but i guess it’s worth mentioning.

[krivx]

Yes, the centre pads are soldered. I tinned the pads lightly and added flux, then placed the chips, then hot air, then soldered the pins.

I just tried putting together a Quartus install to see if it can communicate with the FPGA and the Win10 USB Blaster drivers cause repeat BSOD when using some clone USB Blasters 🙁 I’ve ordered another cheap clone.

I have a spare FPGA (same Asian vendor) and I’m OK at replacing QFPs so that may be the last resort…

[krivx]

OK – some good progress. I downloaded an older version of Quartus Programmer (linked here http://www.firebrandx.com/nespalette.html) and installed it, along with older USB Blaster drivers that were included. My clone does work with these drivers. I was able to successfully detect the FPGA and program the latest 0.78 FW. After disconnecting JTAG and power cycling, my LCD now shows an OSSC FW version message!

I don’t really understand why programming was necessary, unless the pre-programmed IC that came with the kit had invalid FW?

Unfortunately, I get no test pattern on the HDMI output – but I have only tested with one monitor. If I connect a SNES over SCART the OSSC can detect and sync to it correctly, but still no output image.

Without an IR receiver all I can do with the unit is change sources, I have no access to menus so I don’t know if some option needs to be changed.

[Morpheus_79]

Glad you’ve made some progress. Even without a remote and access to all menu Options, your OSSC should at least output a test image after powering it up. If it does not output anything at all, maybe you have a broken IT6613… or a solder bridge or cold solder joint on its pin(s) or on the HDMI connector.

[krivx]

Thanks for the help. I have a feeling my monitor could be part of the issue, it does switch to the digital input when power is applied to the OSSC and it doesn’t go into standby after a few minutes. It just doesn’t show an image, just a black screen and the OSD is not responsive. What would the resolution of the test image be?

I would like to try another monitor before getting a replacement IT6613. The soldering looks good under high magnification. I have tried with the HDMI ESD diodes removed but with no change.

[Morpheus_79]

My TV reports 480p@60Hz for the grey test image.

I don’t know for sure what triggers your (or most) TVs input detection – but if it’s the 5V line in the HDMI connection, chances are your OSSC just simply outputs the usual 5V via HDMI, but no picture at all… since (as far as i know) the 5V pin of the HDMI connector is directly connected to the 5V supply (via a small fuse for protection) with the IT6613 playing no role in that.

[krivx]

I tried it briefly on a friend’s monitor – 720×480 60Hz grey gradients/checkerboard 🙂 My monitor must not support this resolution. Looks like the problem all along was that the board needed re-programming.

[Morpheus_79]

Strange thing, your monitor did not support this very common resolution. On the other hand: it’s a typical standard definition NTSC TV resolution. So maybe it’s more commonly supported by TVs than monitors.

But nice to see you solved those issues. I had similar problems (BSOD) programming the flash chip via JTAG and USB blaster clone (since i bought the simple kit without a preprogrammed flash)… but figured it out myself too. So i know exactly how frustrating such troubleshooting can be… and how satisfying it is, to find a solution.

[marqs]

Test pattern is spec-compliant 480p@60Hz, so all monitors should support that. There’s a chance that one of HDMI TMDS differential pairs have only one wire connected, resulting to degraded signal quality that still may show on some monitors but not on others.

[krivx]

I think it’s more likely that the first monitor I tried is too old to be HDMI compliant. I was connecting with a HDMI->DVI-D cable. I’m curious if it will support higher resolutions or if it’s completely unsuitable. Currently waiting on some TO-92 IR receivers to add to try out while I wait for specified part.

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