SAO Adapter for Voja4 Badge

I hope I didn't make any major mistakes because they are ordered!

If the SPI ends up working, this should be compatible with at least two Adafruit products:

1.5” 128x128, 16-bit color w/MicroSD holder: https://www.adafruit.com/product/1431

MicroSD Card Breakout Board: https://www.adafruit.com/product/4682

These should arrive just before I depart to Supercon!

Although Koppany has only proven the hardware concept with a Pico W at this point, we have enough confidence to move forward with a design for prototyping. Oh, AND, there are schedule pressures so let's build some fast!

I need to finish the routing, but the layout will be similar to this and even fits the SAO Contest size limits!

Hoping to have these available for testing at Supercon 2024 so bring your Voja4!

You already know the input/output cabability of the Voja4 badge is constrained. But is there enough hardware and simulated-4-bit-CPU hardware to enable I2C or even SPI communication? We are going to find out!

Some GPIO-based discrete hardware solutions:

• Two transistors, double NOT, to create open collector mode.
• Is there a better way to make use of the discrete INPUT/OUTPUT signals for I2C?

^^^ This is looking like the right solution. Koppany has a proof-of-concept running on a breadboard, driven by a Pico W. Next step is to port the code to Voja4. I'm working on a schematic/board update that I should be able to get before Supercon. I hope!!!

UART or GPIO to I2C MASTER/HOST:

• Program an 8-pin MCU to be the bridge controller.

UART to I2C MASTER/HOST:

• Is this viable? https://ncd.io/blog/serial-to-i2c-conversion/

I2C [slave] to UART:

Is there a dedicated chip that does the job? Perhaps using a tiny 8-pin MCU is an option.

• The Chip https://www.digikey.com/en/products/detail/nxp-usa-inc/SC16IS750IBS-128/948939
• Retired Sparkfun Breakout https://www.sparkfun.com/products/retired/9981
• Available Breakout https://www.aliexpress.us/item/3256805667898276.html