Yet Another Pi Zero Portable!!

ProxyCell

very nice! how does star fox and super mario world 1 & 2 for snes perform?

moosepr

I have not tried star fox, but super Mario world is quite playable, until I need to start picking things up, then I'm out of buttons! Got the top 2 mapped as start and select so I can get in and out of games

MukDesigns

Decent hack dude.
Is this a proof of concept for further development or a one off?

moosepr

Well I was originally thinking of making a bar top cabinet but my house isn't the biggest so I went portable. Then it became a bit of a challenge to see how stripped down i could go. Was thinking about an open case with just a front and back plate then open sides but then couldn't decide.

Still looking for a good case, im a little worried about the leads from the buttons cutting into the battery

senkun

@moosepr

Very nice! I like the minimalist simplicity of your build/ This screams "put me in a Gameboy Micro case", does it fit? Maybe a smaller Lipo but it looks like a similar form factor. Or just 3D print a case around what you have right now, cut to shape the thin clear plastic from a CD jewel case and use that to insulate the buttons from the Lipo.

Also very interesting to me, it looks like it from the pics you're running the whole thing directly off the Lipo @ 3.7V with power going through the TP4056 to the Pi. That's the great thing about the Zero, seems it can boot even under 3V. So no problems running emulators with just the 2.2" screen? Have you tried plugging more peripherals load on it, usb keyboard or wifi etc.?

Besides power switch on/off, is the uHex doing anything else?Low battery checks for automatic Pi safe shutdown, and automatic power supply off, etc.? The TP4056 does battery protection I was thinking we can omit the uHex? Power on/off can be a simple toggle switch to the battery and shutdown scripted to a GPIO pin. Of course this would be at the risk of SD card corruption since it just cuts power if we forget to shutdown cleanly before power gets too low.

Ha. Many questions, but what you have done is simplicity at it's most elegant and I am inspired. When I get a Zero, this is the first thing I'm gonna do, thank you for sharing!

moosepr

thanks @senkun, the Pi runs well from just the battery, i have even had memory sticks and i have been using an old TP-Link wi-fi dongle top copy games onto it without any problems. The screen is only 2.2 inch, but 240x320 resolution so its not too bad if your eyes can cope.

The uHex is just acting like a basic switch at the moment. I need to add more functionality, im planning on adding a 'neopixel' to give some visual feedback on the battery level, and some safe shutdown/low battery shutdown so that its all nice and controlled. You could replace it all with a plain old switch if you are careful to shutdown first

I did ponder the gameboy micro form factor, but they are so dam expensive these days, its a little bit of an expensive gamble. Im actually tempted to bump it to a 2.8" screen, and pop it all inside a gameboy advance case, would have stacks of space in there!! my design skills are not the best for the 3d printing route

moosepr

just a quick heads up, they are in stock currently

https://shop.pimoroni.com/products/raspberry-pi-zero

senkun

@moosepr

Awesome! Good to hear that even loaded up with wifi it still runs. 240x320 is the best resolution to run our games at, esp off these tft spi screens. Pretty good framerates, minimal tearing and very sharp. All my Pis are self contained units with little tft screens, I have an A+ with a 2.2" so yea a tad on the tiny side, my eyes are coping now but I think in another year or two they won't. Ha. 2.4" or 2.8" would be ideal.

And good to hear too that the uHex is just a glorified switch (for now), means I can just omit it in my future super minimalistic build! But since you have it it would be fantastic to put in more functionality; push button to power up and automatic shut off power supply after the Pi is shutdown and automatic graceful shutdown of the Pi when the button is pushed again and when the power is low (to stop SD card corruption).

Yea, original GB Micros are expensive nowadays. What I had in mind was to rip the case and buttons off a cheapo clone, maybe add more buttons and repaint it. All for around $15 from the usual suspects, or even cheaper if you wait for the slow boat from China.

alt text

senkun

@moosepr

One more thing, is the 2.2" tft one of those with a sdcard slot on the back, running off a ILI9341 driver?

moosepr

Yeah it was this one

http://www.ebay.co.uk/itm/161862594139

Basically the cheapest I could find in the UK. I desoldered the SD card socket from the back to remove some bulk.

I did ponder the tiny generic console route, I have a 1000mah battery that should yeald about 5 hours run time. or i could use a Gameboy advance case and add 2 maybe 3 batteries and get up to 30 hours run time. Although I managed to nab a second pi zero, so I could do both! :-)

senkun

@moosepr

Ha. Thanks for the headsup! I finally managed to grab a Zero and for just £4 too. Can't wait to play with it. And thanks for the link, the UK seller is wonderfully descriptive and knows his stuff. Screen is twice the price of those from China tho, but I'll buy one from him just because.

moosepr

Yeah pimoroni are really good. I ordered the newer version of the zero at 9am on the day it was released, and it arrived the next day.

I normally order my random bits from dx.com, but the 2 week wait for the post made me get the one I did. I have pondered getting a raw screen, then getting a custom PCB made up to contain the buttons and everything, but my PCB design skills are worse than my 3d print design. That would be the holy grail of a tiny handheld though

moosepr

So the postman came!

Toys!

It's actually closer that I thought size wise

senkun

@moosepr said in Yet Another Pi Zero Portable!!:

So the postman came!

Toys!

It's actually closer that I thought size wise

Whoa! Nice! Almost a perfect fit. But then, seems like you need at least a 3.2" screen. Maybe a 3.5" would be best but you'd need to go composite for that size up, gpio 3.5" screens @ 320x480 are too slow.

moosepr

Yeah the original screen is 2.9" so if I bump the screen up to a 2.8" SPI screen, I will keep the same resolution and it should just drop in.

I had a stroke of luck with the buttons, the top of the rubber conductive buttons are exactly the same height as my silicone topped switches. I think I'm going to cut some non conductive sheet of some kind to the same shape as the current motherboard and wire them all in that way.

moosepr

I tried a 2.8" tft i have on an arduino shield, and its almost perfect for the job. The actual display area is a few pixels taller than the hole, and a few pixels narrower, so with some slight mods, it should fit nice!

Im actually struggling to find a 2.8" version of my screen in the UK, so my project might have a few weeks delay while the boat from china makes its way over. i did however find this while digging, its about as minimal as an LCD can get

http://www.tinylcd.com/tiny149/product.php?id_product=22

im just waiting to hear if they will post to the UK, and what chip the display uses

senkun

@moosepr

I'd be interested to know what chip that uses too. The safest bet is of course the 2.8" version of your current 2.2" tft, looks like the same chinese manufacturer, uses the same ILI9341 as well should be a straight drop in.

alt text

moosepr

@senkun

yeah that by backup plan. although i think i may have an issue with the connectors being on the ends of the pcb. The screen edges are actually quite close to the buttons on the GBA. and adding the extra bulk for the brains of the screen that sits on one end, plus the pcb, might just take me too far.

I did ponder geting a custom pcb knocked up that was just the bare minimum for the screen to be used with SPI but have no idea where to start on that one!

moosepr

DAMIT!

Hello

The 2.8 LCD selected by you is not supported in fbtft.
If you want us to do PCB similar to your selection than we can offer you 2 options
100usd development charges
Or
Moq. 25 quantity
One more economical option is we can supply raspberry pi LCD without 40 pin header and than you do the wiring on the gpio header pads
Regards
Tinylcd

moosepr

Right!! i have a plan. I have been doing some digging and the ili9341 screens are actually all the same!! there are 2 variations, the larger have touch, and the smaller dont, the first 14 pins are the same regardless of the presence of touch. So all i need to do, is buy a naked 2.8" screen, and unsolder the 2.2" screen i currently have, and transplant the 2.8" screen on top!! that way the pcb is actually the same size, if not smaller than the screen, and there is more space to play with!!

now to wait for the good ship chinapost :D