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83 lines
3.0 KiB
Markdown
83 lines
3.0 KiB
Markdown
The **FunKey S** is the world's smallest foldable retro-gaming console.
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Holding a world's record is great, but we wanted a device that was
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_actually_ playable and that still could be attached to a keychain.
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Reaching this goal required more than just the usual job to shrink
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everything you can: it required a radical change in the design itself.
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## Foldable Design
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The idea to use a foldable clamshell design came up rapidly as the
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only way to get _both_ a small form factor when closed, and offer the
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largest screen and keypads while playing.
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But this solution also brings a lot of challenges, as the required
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hinge make connections between the 2 halfs of the shell more
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difficult.
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However, this has been done before in the classic GameBoy Advanced SP,
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or in many clamshell cellphones from some years ago, so why can't we?
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## Design Goals
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Passed this first design decision, we fixed ourselves some additional
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goals in order to provide the user a good gaming experience:
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- have a CPU that is powerful enough to be able to emulate most
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retro-gaming consoles, up to the PS1
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- have a good quality screen with a resolution large enough to
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display even the games featuring small texts
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- have a set of keys and pads large enough and complete enough to be
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able to play comfortably
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- have a built-in audio capability (who can play without sound?)
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- be able for a 6-year old child to add games and emulators
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- as an extremely nomad device, be able to stop playing just by
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closing the console, and restart when opening it just where you
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left (we call this feature "**_Instant Play_**")
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## Design Constraints
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Besides the constraint brought by the hinge listed above, the main
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difficulty is due to the maximum device dimensions that should not
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exceed those of a (large) car key.
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And because of the foldable design, the most constrained dimension is
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thickness: having a folding screen also means doubling the plastic
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enclosure around the screen and the other internal parts.
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In order to meet these constraints, we had to take more
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(heart-breaking) decisions:
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- a CPU with external DRAM chips would take too much real-estate on
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the PCB, so we had to find a CPU with integrated DRAM
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- an audio Jack would be very difficult to integrate, so we decided
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to use an internal speaker instead
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- an USB C connector is too thick and large, so we used a Micro USB
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connector instead
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- a Micro SD connector with external access would be too large, as
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the required "push/push" mechanism, plus the mechanical design to
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make sure the card does not get loose make the solution much larger
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- because of real-estate constraints on the PCB as well as power
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consumption constraints, we decided to not integrate Wi-Fi and/or
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Bluetooth
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- the only keypad technology able to meet our thickness goal is using
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integrated tactile switches
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- battery capacity had to be adjusted to the maximum available
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internal volume, using standard battery dimensions
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--8<--
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includes/glossary.md
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--8<--
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