## esp32 boards
### Blinky
GPIO 0 float high, GPIO 2 float low - Flash boot
GPIO 0 gnd low, GPIO 2 float low - Serial boot
ESP32-S pins
pin25 - programming
1,38,15 - GNDs
2 - pwr, 3 - enable
ADC1 (ADC2 unavailable w/ wifi)
Sep 2019
-
Oct 2019
Move ADC port to an ADC1 Pin pin4-9
Another ADC Pin to 3.3v input?
Another ADC Pin to vdivider + 15v input
Add 3.3v to top of ADC
drop 3.3io and 3.3 power ports
add oled/serial port at edge
short rx/tx lines pin34&pin35
Nov-C 2019
Reset line (no room)
connected 3v bus
vreg cap
volt Divider ADC (no room)
add pullup resistor to one port (for i2c temp sensor)
U0 TX 500ohm R close to esp32 (reflections)
## wall switch
switch
switch backlight
photosensor
distance sensor
status led
lcd display
## photoresistor
## signal harmonics
https://electronics.stackexchange.com/questions/33372/spi-bus-termination-considerations