Ghosts αSNES
- Thread starter YveltalGriffin
- Start date
-
- Tags
- custom pcb snes
- Joined
- Oct 17, 2023
- Messages
- 1
- Likes
- 0
I'm wondering how I would get started with printing this PCB and bringing the portable version to life!
I just don't know where to start... I have no PCB design work, but am pretty skilled at programming, so where would I start to get this thing running?
I just don't know where to start... I have no PCB design work, but am pretty skilled at programming, so where would I start to get this thing running?
This project has been stalled for a long time due to RGB video woes. As @thedrew and @Y2K can attest, dealing with 240p RGBS video in a portable is an absolute NIGHTMARE. No 640x480 LCD driver boards support it, and all the existing video scaler solutions are problematic.
For context, I used Shinobi Scaler in the PS Hanami and was dismayed by the power consumption and heat output: 2.4W when running from 5V! It looks great, but it's a power hog. Also, it has some minor glitchiness and isn't super consistent. Sometimes it can't lock onto sync perfectly which results in noisy video that persists until a reboot. Also, the conversion chain when using Shinobi is absurd: analog RGBS > digital RGB inside TV5725 > analog VGA > digital RGB24 for LCD. That's THREE analog-digital conversions.
For a while I convinced myself that switching to the 2Chip and utilizing SNES-TST for pure digital video was the solution. But abandoning ALL of my existing αSNES work is just too hard to stomach, and I think the 2Chip chipset is really ugly and messy compared to the elegant 1Chip.
Recently, @thedrew did some undervolt testing with Shinobi Scaler and cut the power in half by running the 3.3V rail at 2.5V and the 1.8V rail at 1.5V. This is more reasonable, so I created Shinobi Scaler 2 to take advantage of his findings:
But this still doesn't solve the other issues of glitchiness, video noise, and needing WiFi to set up the dang thing! So I kept investigating.
I tested PixelFX's Retro GEM Shiny and think it's a great solution for the N64, PS1, PS2, and Dreamcast. But SNES support for the GEM (using a video ADC add-on) is months if not years away.
With how amazing my Retrotink 4K makes old consoles look, I decided to try out some of Mike Chi's cheaper offerings, starting with the RAD2X SNES cables. The RAD2X is essentially a miniaturized Retrotink 2X and uses an off-the-shelf ADC and HDMI transmitter to linedouble SNES RGBS to 480p HDMI.
(for those wondering, the interface between the ADC and HDMI transmitter is YCbCr, not 24-bit RGB, so a direct drive like the GEM is not possible.)
The output is integer scaled (512x448) in a 720x480 frame and looks quite nice on the ZJ050NA-08C LCD.
The RAD2X draws about ~200mA @ 5V while running, which matches Shinobi Scaler 2. There are definitely additional power savings on the table from strategically replacing LDOs on the PCB with switchers. It's also ~1/3 the size of a Shinobi Scaler.
The only thing it lacks is scanlines. But this is solvable too:
The conversion chain with a RetroTINK 2X-SCART will be: analog RGBS > digital YCbCr > digital HDMI > digital RGB24 for LCD. So only ONE analog-digital conversion, which is way, WAY better than Shinobi Scaler.
For context, I used Shinobi Scaler in the PS Hanami and was dismayed by the power consumption and heat output: 2.4W when running from 5V! It looks great, but it's a power hog. Also, it has some minor glitchiness and isn't super consistent. Sometimes it can't lock onto sync perfectly which results in noisy video that persists until a reboot. Also, the conversion chain when using Shinobi is absurd: analog RGBS > digital RGB inside TV5725 > analog VGA > digital RGB24 for LCD. That's THREE analog-digital conversions.
For a while I convinced myself that switching to the 2Chip and utilizing SNES-TST for pure digital video was the solution. But abandoning ALL of my existing αSNES work is just too hard to stomach, and I think the 2Chip chipset is really ugly and messy compared to the elegant 1Chip.
Recently, @thedrew did some undervolt testing with Shinobi Scaler and cut the power in half by running the 3.3V rail at 2.5V and the 1.8V rail at 1.5V. This is more reasonable, so I created Shinobi Scaler 2 to take advantage of his findings:
But this still doesn't solve the other issues of glitchiness, video noise, and needing WiFi to set up the dang thing! So I kept investigating.
I tested PixelFX's Retro GEM Shiny and think it's a great solution for the N64, PS1, PS2, and Dreamcast. But SNES support for the GEM (using a video ADC add-on) is months if not years away.
With how amazing my Retrotink 4K makes old consoles look, I decided to try out some of Mike Chi's cheaper offerings, starting with the RAD2X SNES cables. The RAD2X is essentially a miniaturized Retrotink 2X and uses an off-the-shelf ADC and HDMI transmitter to linedouble SNES RGBS to 480p HDMI.
(for those wondering, the interface between the ADC and HDMI transmitter is YCbCr, not 24-bit RGB, so a direct drive like the GEM is not possible.)
The output is integer scaled (512x448) in a 720x480 frame and looks quite nice on the ZJ050NA-08C LCD.
The RAD2X draws about ~200mA @ 5V while running, which matches Shinobi Scaler 2. There are definitely additional power savings on the table from strategically replacing LDOs on the PCB with switchers. It's also ~1/3 the size of a Shinobi Scaler.
The only thing it lacks is scanlines. But this is solvable too:
- RetroTINK 2X-Pro can add scanlines, but only accepts YPbPr input. Not ideal for SNES
- RetroTINK 2X-SCART can add scanlines and accepts RGBS directly! Perfect for SNES, but it's discontinued.
The conversion chain with a RetroTINK 2X-SCART will be: analog RGBS > digital YCbCr > digital HDMI > digital RGB24 for LCD. So only ONE analog-digital conversion, which is way, WAY better than Shinobi Scaler.
Last edited:
- Joined
- Apr 29, 2020
- Messages
- 109
- Likes
- 132
Awesome!! I am so thrilled that you are coming back to this project! Definitely looking forward to seeing what you come up with!
Once you RE the RetroTINK 2X-SCART, will we still need to buy one to make the build or will that not be necessary?
Once you RE the RetroTINK 2X-SCART, will we still need to buy one to make the build or will that not be necessary?
Yes, parts will need to be harvested from a 2X-SCART. The TINK's firmware is proprietary and protected, and I have no interest in cracking or cloning it
Last edited:
My 2X-SCART arrived! I like the silk labels for the input pins. The PCB has a couple mystery ICs; one seems to be an LM1881, and another is probably a THS7374. Not sure what the others are yet, but it'll become clear once I generate a schematic. The FTDI chip can definitely be yeeted once I update the PIC to the latest firmware. Overall, the circuitry is extremely miniaturizable, which is exciting!
Unsurprisingly, the video output is basically identical to the RAD2X.
The scanline filter looks extremely good. Using a 2X-SCART is well worth it for this feature alone.
Scanlines disabled on the left, scanlines enabled on the right.
Close-up:
The only downside of enabling scanlines is the huge decrease in brightness that it causes. The 2X-SCART has no gamma boost options like the PixelFX products to compensate for this. My only hope is purchasing a high-brightness version of the 5" 640x480 LCD. The stock panel is a measly 250 nits, but 800nit versions exist and should be able to pump out enough light to make up for the doublestrike filter.
Unsurprisingly, the video output is basically identical to the RAD2X.
The scanline filter looks extremely good. Using a 2X-SCART is well worth it for this feature alone.
Scanlines disabled on the left, scanlines enabled on the right.
Close-up:
The only downside of enabling scanlines is the huge decrease in brightness that it causes. The 2X-SCART has no gamma boost options like the PixelFX products to compensate for this. My only hope is purchasing a high-brightness version of the 5" 640x480 LCD. The stock panel is a measly 250 nits, but 800nit versions exist and should be able to pump out enough light to make up for the doublestrike filter.
- Joined
- Jan 31, 2016
- Messages
- 1,318
- Likes
- 2,818
- Portables
- 6
I wonder if you could "boost gamma" by replacing the 75 ohm termination resistors with lower value ones. Not sure if this would help, or just make things worse by clipping and blowing everything out. Guess it depends on how the 2x handles the input
I'm a little wary of messing with the video levels in case it impacts the colors or contrast. But I found a workaround for now. Increasing the backlight current by ~1.75x makes the brightness in scanline mode good enough.
The stock boost converter is unhappy outputting this much current, but I can replace it with a better one in the final design. Hopefully this doesn't cook the panel LEDs long term
The stock boost converter is unhappy outputting this much current, but I can replace it with a better one in the final design. Hopefully this doesn't cook the panel LEDs long term
S T A C C
This is the true Manhattan Project.