Simple two-way message appliance

First user alerts the second user to come2bed via status-light, and the second user responds with positive or negative response that the first user can see.

• 1x: Adafruit Feather Huzzah 8266 https://www.adafruit.com/product/2471
• simple button
• 1 protoboard
• wire

• button input on pin 5 (see learnings)
• button LED on pin 16
• GND to button input, LED

• FATAL
  • Always throws a DEBUG message and blinks built-in LED at (error code x 1 second) intervals
  • ERR 01: Can not connect to MQTT broker. Device must be restarted.
  • ERR 02: Can not connect to Ethernet. Device must be restarted.
  • ERR 03: Can not connect to WiFi. Device must be restarted.
• CAUTION - NOT IMPLEMENTED, see FR request
  • throws a DEBUG message
  • blinks built-in LED at (error code x 1 second) intervals
  • ERR 04: MQTT publish failed.

• [P2]071620: button too dim (resistor, change LED?)
• [P1]101320: cub2bedSub pulls last-1 message, not last message, causing logic issues?
• [P2]101520: If cub2bedPub fails, downstream is not handled properly
• [P2]101520: statusLightPub On should be handled by c2b server, not client, ensuring light only goes on when the server has recognized cub2bed message from client
• [P2]102420: Move local MQTT server to named entry instead of IP address so DNS can resolve it if entry changes
• [P2]110620: Client doesn't have a timeout to reset its state if no server message is received
• [P1]122320: Client appears to light the button every 10 seconds for less than 1 second

• [P3]101220: MQTT- [P3]110920: publish to secondary MQTT broker
• [P3]111020: publish to multiple MQTT brokers
• [P2]111120: ThinkSpeak investigation
• [P3]120620: Error messages to MQTT broker
• [P1]012421: Async blinking of built-in LED for non-FATAL errors (e.g. MQTT publish)

• 071620 - Breadboard makes box fit not; 60mm might be tight either way. Might want to take z-axis to 65mm
• 101220 - Seem to be having trouble with button input on multi-purposed ESP8266 pins. No issues on SCL/SDA

• 101220
  • new code branched from cub2bed_client
  • messaging via 900mhz radio removed
  • messaging via MQTT topic added
• 101520
  • MQTT code improvements
• 101620
  • [I]101620 [P1]; Example ping code fires every loop() but docs say to ping infrequently within the keepalive window to avoid packet collision -> add timer loop to ping at MQTT_KEEP_ALIVE
• 103020
  • [I]101720 [P2]; blue LED on Huzzah board needs to be supressed (or piped!) -> moving button LED to pin 16 from 2 to separate from on-board LED. Added code to disable on-board LED.
  • [FR]051920 [P3]; Use the builtin LED as a crude indicator (packet send, receive, etc.) -> closed as duplicate to 102420 P2 issue
• 010221
  • [FR]100120 [P3]; validate Ethernet code -> code aligned with functioning status_light Ethernet code
  • [FR]111020 [P3]; combine MQTT publish code blocks for AdafruitIO MQTT and generic MQTT -> complete
  • [I]101220 [P3]; AdafruitIO feeds not setup properly, see Publish setup code -> closed because of MQTT code merge
  • [I]102420 [P1]; Need an error indicator for for non-DEBUG, while(1) errors, MQTT connection errors -> while(1) error handling improved and now blinks button LED in unique pattern to indicate fatal error
• 012421
  • [FR]123120 [P2]: Add error blink codes to onboard LED for while (1) -> Adding BUILT_IN_LED blinking matching the fatal error code, aligning with new code in air_quality