TNbadge

A blinky-light badge in the approximate shape of Tennessee

Join the Tennessee Cybersecurity Discord and participate in discussion about this badge.

User's Guide

Features

human-accessible output

• 5 of 2.0mm square addressable RGB LED (APA102) at the approximate locations of the top 5 population centres (west to east: Memphis, Clarksville, Nashville, Chattanooga, Knoxville)
  on-chip SPI (SCLK from pin 9 (D8/GPIO8), MOSI from pin 11 (D10/GPIO10))

• 1 of user-populated LED-footprint, switched 5V supply with current-limiting resistor
  from pin 7 (D6/GPIO21)

• 1 of 212x104 pixel 2.13 inch epaper display (grey/black/red) populated at either of 2 locations (one almost entirely on-board; one almost entirely off-board and mounted from behind to not obscure Chattanooga's LED)
  on-chip SPI, /CS from pin 4 (D3/GPIO5), DATA/CMD from pin 2 (D1/GPIO3), /RESET from pin 7 (D6/GPIO21), BUSY to pin 1 (D0/GPIO2)

human-accessible input

• 1 of LDR, darkness-proportional voltage at ADC
  to pin 3 (A3/D3/GPIO5)
  unfortunately, the chip configuration in Espressif's Arduino chip-support package connects a non-functional ADC to this pin, so this can't work without a deeper dive :(

• 1 of pushbutton digital input to pin 10 (D9/GPIO9)

electronic

• 1 .. 3 of SAO V.1.69bis master connector populated at any of 4 locations not obstructed by epaper
  on-chip I2C (SCL on pin 6 (D5/GPIO7), SDA on pin 5 (D4/GPIO6)), GPIO1 on pin 2 (D1/GPIO3), GPIO2 on pin 1 (D0/GPIO2)

• USB-C for power and programming

• 1000mAh LiPo battery

• battery voltage /2 at ADC
  to pin 3 (A2/D2/GPIO4)

• on-chip Bluetooth Low Energy / WiFi

• power ON/OFF switch

• epaper display / LED enable switch (to maximize epaper lifetime by disconnecting power other than when required for update, and encourage this by having LED power mutually exclusive with epaper power)

design considerations

• minimal components on front allowing maximum space for silkscreen art

• maximal GND-connected fill on both top and bottom for even background under soldermask (and to reduce electrical noise)

• flat empty space on back for LiPo battery to rest snug against PCB

• maximum flexibility for user customization, both physical and logical

• components chosen (and footprints customized) for hand-solderability where possible

software

prototype implementation

ideally, watches for pushbutton held down at boot to signal display update requested; after display is updated, user flips epaper/LED switch for blinky goodness

possible behaviour-change triggers:

• ambient light level

• dropping battery voltage

• proximity of other badges, which specific badges they are, and their interaction history

• external access over BLE/WiFi by not-a-badge

production timeline

Board design is now locked down.

• First batch of badge kits (SMD components soldered onto PCB, through-hole assembly to be completed by user) distributed in April 2024 to software development volunteers

• Artwork has been added to board silkscreen

• epaper displays are now in hand

• remaining PCBs to be delivered mid June

• remaining CPU modules to be ordered mid June

• SMD assembly to start when PCBs arrive

• bagged kits distributed as soon as possible, but no later than DEF CON 32 in Las Vegas