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Dreamcast VMU Pi [Completed]

Posted: Wed Mar 22, 2017 1:35 am
by satri360
I am working on the Sega Dreamcast Visual Memory Unit (VMU) as it might be a good fit for Pi Zero.


Parts
  • Pi Zero (Pi Zero W)
  • Enameled Copper Wire AWG 35
Software
  • FBCP
  • FBTFT (Genius Nostro's SSD1351 driver)
  • Retrogame
  • Retropie w/ Emulation Station
Instruction Next...
Adding XYLR keys would be neat. I might need to design the all-in-one PCB just to add amp and speaker. Yeah game needs audio!
Thanks Adafruit/Retropie and all of other talented people to build this project.

Re: Dreamcast VMU Pi

Posted: Wed Mar 22, 2017 2:58 am
by moosepr
you have set yourself a challenge there!!! [mention]abrugsch[/mention] has started a similar project here http://www.sudomod.com/forum/viewtopic.php?f=11&t=2240

i think the biggest hurdle will be the depth. the pi zero is 5mm thick, the screen probably 2mm thick, the battery 5mm thick, and after a quick google, the vmu is 16mm thick, so that leaves 4mm plastic case thickness

the controller board for your oled is interesting. did you chop up the adafruit one?

Re: Dreamcast VMU Pi

Posted: Wed Mar 22, 2017 4:01 am
by abrugsch
yeah, that controller board is going to get in the way. I'm using a SPI TFT @128x128 and will probably do a custom board with the button landing pads, the tft ribbon solder pads, Pi directly to the back of the PCB a la @moosepr's PiCB-tft.

for the best fit, I've discovered that the lanyard notch is perfectly placed and sized for the uSD card to poke out once the cutout is removed

Re: Dreamcast VMU Pi

Posted: Thu Mar 23, 2017 12:28 am
by satri360
moosepr wrote:you have set yourself a challenge there!!! [mention]abrugsch[/mention] has started a similar project here http://www.sudomod.com/forum/viewtopic.php?f=11&t=2240

i think the biggest hurdle will be the depth. the pi zero is 5mm thick, the screen probably 2mm thick, the battery 5mm thick, and after a quick google, the vmu is 16mm thick, so that leaves 4mm plastic case thickness

the controller board for your oled is interesting. did you chop up the adafruit one?
For sure I am not the first one to think about the VMU as it has complete D-pad + AB keys and nice tiny display. I have to cut almost 70% of the OLED PCB to give some space for PowerBoost. Yes I am still tackling to fit everything in this small case particularly the inductor on the PowerBoost is way too tall. This is the primary reason to consider the custom PCB.

I also need to cut out the back of the VMU and battery is about to come out now. 128x128 resolution is not very attractive and I would appreciate if you can share some of the SPI-controllled display with higher resolution say 320x240.

Re: Dreamcast VMU Pi

Posted: Thu Mar 23, 2017 12:45 am
by moosepr
You don't technically need the power boost! You can actually run the pi as low as 3v (I have read it will even run as low as 2.7v) so in my projects I have been powering the pi straight from the li-po battery! The only thing you need to be sure of, is that the battery is protected so it doesn't become over discharged. Some battery's have a tiny pcb attached to them which allow this.

It would mean that charging is more difficult but you will save space

There is a spi screen of the same size that would work easier on a custom board (fewer components needed) but they are still only 128*128 resolution. It is however the perfect resolution for pico-8 :D

Re: Dreamcast VMU Pi

Posted: Thu Mar 23, 2017 1:36 am
by abrugsch
Yes i don't think there are (m)any SPI screens that size with a higher res that are easily available but I'm sure they are out there...

Re: Dreamcast VMU Pi

Posted: Thu Mar 23, 2017 2:38 am
by moosepr
best i have found is 128*160

https://www.aliexpress.com/item/1-44-in ... 84209.html

but that will probably just be a little taller to make space for the extra 32 pixel rows

if you use something like this in place of the adafruit powerboost, then your battery will be protected, will be chargeable, and its smaller (you just have no boosting feature, which i dont think is needed)

https://www.aliexpress.com/item/10-pcs- ... 30344.html

Re: Dreamcast VMU Pi

Posted: Sun Mar 26, 2017 6:49 am
by obsidianspider
I managed to find your test video on YouTube last night at around 2 AM, so of course now I am attempting this as well. Thanks to @moosepr for directing me to this thread from my post over at the RetroPie forum.

Which OLED are you using? Is it the 1431? https://www.adafruit.com/products/1431

Re: Dreamcast VMU Pi

Posted: Sun Mar 26, 2017 12:14 pm
by obsidianspider
moosepr wrote:You don't technically need the power boost! You can actually run the pi as low as 3v (I have read it will even run as low as 2.7v) so in my projects I have been powering the pi straight from the li-po battery! The only thing you need to be sure of, is that the battery is protected so it doesn't become over discharged. Some battery's have a tiny pcb attached to them which allow this.
When you're running directly off the lipo, are you wiring to the 5V pins on GPIO, or 3.3V?

Re: Dreamcast VMU Pi

Posted: Sun Mar 26, 2017 12:40 pm
by moosepr
obsidianspider wrote:
moosepr wrote:You don't technically need the power boost! You can actually run the pi as low as 3v (I have read it will even run as low as 2.7v) so in my projects I have been powering the pi straight from the li-po battery! The only thing you need to be sure of, is that the battery is protected so it doesn't become over discharged. Some battery's have a tiny pcb attached to them which allow this.
When you're running directly off the lipo, are you wiring to the 5V pins on GPIO, or 3.3V?
power into the 5v, then it can get regulated to 3.3 and other voltages for the processor.

you can also get a nice 3.3v supply from the pi for the screen :D