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EMES - Epic Minimalist Entertainment System

A very minimalist handheld console powered by ATTiny10 MCU, featuring 10x7 vintage LED display

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A very minimalist handheld console with removable cartridges. It features Plessey GPD340 vintage LED display IC for the screen, 4 buttons, and a buzzer for sound.
There is no MCU on the baseboard, instead an ATTiny10 MCU is placed on each cartridge, sort of like the Microvision console (the first handheld console with swapable cartridges).

This is an attempt to build a full-fledged game console, i.e. with multiple games, sound, multiple buttons - all that using one of the cheapest and lowest-end 8-bit MCU currently on the market. Thus, ATTiny10 is my MCU of choice for this project. Although, there are even cheaper and lower-spec MCUs out there,  ATTiny10 seems to be minimally viable for this purpose.

Current progress

First version of the baseboard and cartridge PCBs were designed and ordered. The first PCB prototype was assembled.

Two playable games have been implemented - variations of Pong and Snake. And also a test program - to check if the display, buttons and sound do work together. Here is a short demonstration:

Implementation details

ATTiny10 has the following specifications:

  • Main clock frequency: 8MHz
  • Program/data flash: 1KB
  • RAM: 32 bytes
  • 8-bit ADC
  • 4 GPIOs

The display - GPD340 requires at least 4 output lines to control (serial data, 2 clock inputs, PWM brightness control), one output is needed to make some noise with the buzzer, and there're 4 buttons. So all these channels need to be multiplexed to just 4 GPIOs.
So I came up with the following GPIO assignment:

  • PB0 - is shared between the keyboard and serial data input for the display
  • PB1 - outputs the same PWM for both - brightness control and the buzzer. Most of the time it outputs high-freq (>20KHz) PWM, so the buzzer appears silent. When we need to produce a sound, we just switch to a lower frequency and adjust duty cycle so the display is not too bright/dim.
  • PB2 - serial clock input for the first half of the display
  • PB3 - serial clock input for the second half of the display

The buttons connected to PB0 via a resistor ladder, so each button causes different voltage levels which could be read by the ATTiny's ADC to determine which button is pressed exactly.

The game cartridge also acts as the main power switch/jumper: when inserted, pins 7 and 8 on the edge connector are shorted allowing current to flow.

The very first prototype was built on a breadboard:

And this breadboard also doubles as a programming rig for the cartridges. There is a 12V boost converter with a switch, which is required to program an Attiny10 when the reset function on the pin PB3 is disabled.

All firmware is written in either C or assembly using avr-gcc and uploaded to the device with a cheap USBASP programmer.

EMES_04.gif

Graphics Interchange Format - 11.42 MB - 09/12/2024 at 17:46

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EMES_03.gif

Graphics Interchange Format - 16.68 MB - 09/06/2024 at 23:37

Preview

emes_base_board_schem.png

Portable Network Graphics (PNG) - 46.33 kB - 09/06/2024 at 23:37

Preview

emes_cartridge_schem.png

Portable Network Graphics (PNG) - 17.01 kB - 09/06/2024 at 23:37

Preview

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Discussions

Dylan Turner wrote 09/09/2024 at 15:11 point

Nice! I made a similar project not too long ago with the whole "cartridges as cpu + mem" thing meant to be a business card. I've been working on a new version of it, actually.

  Are you sure? yes | no

senily64dx wrote 09/09/2024 at 11:53 point

32 Bytes of RAM? And I thought the Interton VC4000 had little, at 37 Bytes. And it's running at 1/10th the clock speed (except that the CPU takes multiple clock cycles per operation and would run circles around the S2650 CPU when clocked at the same speed)

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Michael wrote 09/09/2024 at 13:34 point

Actually, RAM is not what I'm struggling with - 32B is just enough for small games like pong or snake. I'm mostly struggling to fit everything in 1KB of program flash - this one runs out very quickly, a lot of compromises must be made in game logic.

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parkview78 wrote 09/09/2024 at 02:52 point

A great inspirational project!  What is the part number of the 8 wire connector and where did you buy it from?

  Are you sure? yes | no

Michael wrote 09/09/2024 at 13:20 point

Thanks! This is the datasheet for the part: https://eu.mouser.com/datasheet/2/40/9159_600-3366826.pdf

I got it from Mouser, it goes by this p/n there: 009159008603906

  Are you sure? yes | no

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