In collaboration with Jeremy, I just finished the PCB design and ordered some samples for Supercon!

This effort to add some bling and make the system more "snap together" unintentionally turns SAOfinity into a badge! By designating one tile as the primary control tile, and plugging in an MCU to that board, you''ll be able to control the built-in chain of LEDs, and communicate with the I2C and GPIO on other tiles. I will use the SAO Demo Controller I designed as an example in the next log entry.

FEATURES

• RGB LED: Built-in, daisy-chainable to be controlled from a primary SAOfinity tile board. Allows control of RGB LED as a backlight to the SAO on display on a given tile. Solder jumpers make it flexible!
• CONNECTORS: PCB is ready for right angle 0.1 inch pitch 7-pin edge connectors to eliminate wires. All 7 pins are not required to use the board - just 2 pins for power are sufficient. A third pin enables access to the RGB LED. The other four pins enable I2C and GPIO1&2 connections between tiles
• QWIIC: A spot for you to add a QWIIC connector because that should be a great part of the SAO ecosystem too!
• POWER: Designed to operate at 3.3V for now. Dedicated pads (or a connector if choose) to power your SAOfinity creativity. See below for more details. Bring-your-own-power-source.

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V1 IMPORTANT NOTES ABOUT POWER OPTIONS:

This first version (V1) has two pins for 3.3V power (J5) to be supplied by any 3.3V source. The 3.3V supply is the common voltage rail shared between all SAOfinity tiles when the interconnecting right-angle headers are used. Because most readily available 3.3V sources are lower current, it may be necessary to sub-divide your SAOfinity tile grid into multiple power zones and supply 3.3V power into each zone from a separate 3.3V source. This requires NOT interconnecting the 3.3V power line between those zones through the right-angle headers between select tiles.

NEWEST PLAN 3.3V at 4A from USB C... maybe? 

https://hackaday.io/project/195130-ppstrigger-v2-usb-pd-pps-trigger-with-cc-cv

And

https://www.ebay.com/itm/285420629162?var=587342424163

POWER - PLAN A [1.0A @ 3.3-5V adjustable from Micro USB or 1S LiPo]

*** NOT RECOMMENDED FOR V1 ***

Requires resistor mod. Stand-alone battery powered or Micro USB. In the first non-PCB prototype set of 16 SAOfinity tiles, I'm running power from an Adafruit LiPo charger/boost board and battery through the chain of SAOfinity tiles:

• Charger and Power Boost https://www.adafruit.com/product/2465 ($19.95)
• Battery (variety) https://www.adafruit.com/product/5035 ($10-30)

Does NOT need a battery to run from USB port. I think it's OK to run that way - seems to work fine.

I modified the power boost board by changing the output voltage setting to 3.75V (a little bit high for SAO spec but some room for the voltage to sag). R3 has been replaced with a 1.3 MOhm resistor.

POWER - PLAN B [1.0A @ 3.3V from 5-18V or USB C (5V) or 1S LiPo or Solar MPPT-like]

*** SIMPLEST FOR V1 - limited power output though ***

Compared to PLAN A it's better with no mods, lower cost, proper USB C. Power path support. However, it doesn't add any more 3.3V power output capability.

Charge via bq2518. Buck switching regulator TPS62569 (90-95% eff., 3.4-5.5V in, up to 2A if used with proper inductor).

• https://www.adafruit.com/product/6092 ($9)

POWER - PLAN C [4.0A @ 3.3V from 4.5-28V]

*** If this delivers as advertised, use with USB C PD selectable voltage board to power MANY tiles! ***

• https://www.ebay.com/itm/285420629162 ($2.50 + $8.00 shipping from China)

Use with one of these:

1. Solder jumper selectable voltage rail: https://www.adafruit.com/product/5807 ($6)
2. Switch selectable voltage rail: https://www.adafruit.com/product/5991  ($10)

POWER - PLAN D [0.8A @ 3.3V and 3A @ 5V from USB C 5V]

*** NOT RECOMMENDED FOR V1 *** May be for individual tiles powered by future (V2) 15V rail.

STM LD1117 linear regulator (heat producer) drops USB C 5V input to 3.3V @ 800 mA (and passes through 5V at 3A):

• PCBA https://www.digikey.com/en/products/detail/artekit-labs/AK-USBSUPPLY-C/22543800 ($8.81)
• IC (15V max input)  https://www.digikey.com/en/products/detail/stmicroelectronics/LD1117ADT33TR/669253 ($0.32/ea @ 100pc)

POWER - PLAN E [2.0A @ 3.3V from 5V header pins]

TPS62827 converts 3.4-5.5V input to 3.3V @ 2 Amps practically (3A peak):

• PCBA https://www.adafruit.com/product/4920 ($7)

POWER - PLAN F [1.2A @ 3.3V from 4.5-21V header pins]

MPM3610 converts 4.5-21V input to 3.3V @ 1.2 Amps. Ideal for use with high voltage USB C PD rail.

• Board https://www.digikey.com/en/products/detail/adafruit-industries-llc/4683/12822323 ($6)
• IC https://www.digikey.com/en/products/detail/monolithic-power-systems-inc/MPM3610AGQV-Z/5292908 ($1.47/ea at 100pcs)

POWER - PLAN BY Y-O-U!

Use whatever makes sense from your parts bin. Just keep the voltage rail near 3.3V. Remember, you can split up the SAOfinity grid into multiple sub-sections and provide adequate power to each sub-section. You don't have to provide a single power input for everything.

POWER - FUTURE VERSION

To enable larger load capacity, I think it makes sense to move the interconnection power rail up to a higher voltage driven with a USB C PD socket. Allowing the user to select the PD voltage is a bonus feature. Then step-down the voltage to 3.3V at every single SAOfinity tile. Examples:

1. USB C  PD input 5-20V main input to first SAOfinity tile in the series (secondary PCBA)
   1. Solder jumper selectable voltage rail: https://www.adafruit.com/product/5807 ($6)
   2. Switch selectable voltage rail: https://www.adafruit.com/product/5991  ($10)
2. Regulated to 3.3V at each SAOfinity tile
   1. 4.5-21V in to 3.3V @1.2A output! https://www.adafruit.com/product/4683
   2. LDO 20V->3.3V @0.5A ($0.71/ea @ 100pcs) https://www.digikey.com/en/products/detail/stmicroelectronics/KF33BD-TR/1038077