Software

MQTT Topics

See init3.lua and calls to logdata, but in summary:

• Topics set by the device:
  • .../boot -- heartbeat, boot announcement, and LWT.
  • .../th -- temperature probe result
  • .../zz -- temporary debug topic
• Topics set by the user/controller:
  • .../fan -- on or 1 to force fan on, otherwise automatic.
  • .../mode -- off, cool, heat, or emht
  • .../target -- the target temperature, in half-degrees Celsius

Note

Temperatures are reported and consumed (in .../target) in half degrees Celsius. (Funky, ain't it?)

Control-side

I suggest a wrapper shell script, possibly named thermostat.sh or something, along these lines, filling in the ... appropriately:

#!/bin/bash
mosquitto_pub -h ... -u ... -P ... -t ".../$1" -m "$2" "${@:3}"

Then it's a matter of ./thermostat.sh fan on, ./thermostat.sh mode cool, or ./thermostat.sh target 50.

Help! My broker's down! My network's down!

Don't panic! If your network is still online, you can telnet in to the device. Failing that, the serial console is still viable (best grab the pins with your own TTL adapter, as the nodemcu board has its own voltage regulator and will attempt to power the thermostat's 3.3V rail from USB, potentially fighting the other voltage regulator!). Failing that, just put the original thermostat back, yeah?

In any case, you can simulate the receipt of a MQTT message from the Lua interpreter prompt (or diag exec via telnetd). Try one of these:

nwfnet.onmqtt["th"](mqc, mqttTargTopic, "60" )
nwfnet.onmqtt["th"](mqc, mqttModeTopic, "off")
nwfnet.onmqtt["th"](mqc, mqttFanTopic , "on" )

Hardware

Peripheral Setup

GPIO	IX
16	0	not used but somewhat special; "XPD"
5	1	1-Wire
4	2	I2C SDA
0	3	I2C SCL / pull 0 for bootloader / bounce low to stop init
2	4	WS2812, by necessity of hardware
14	5	not used, but reserved for PCF IRQ
12	6	not used
13	7	not used
15	8	Pull low to select boot mode

Note

• GPIO2 (ix 4) is also the onboard LED
• GPIOs 1,3 (ixes 9,10) are used for serial UART
• GPIOs 6-11 (incl. 9,10, ixes 11,12) are used in chatting with the flash chip

I2C Peripherals

We have a PCF8574A attached to us on the I2C bus at address 0x38. Its IO lines are used as follows:

P0	Relay 1: Fan
P1	Relay 2: AC
P2	Relay 3: Heat
P3	Relay 4: Em Heat
P4
P5
P6
P7

1W Peripherals

We have a DS1820 temperature probe attached to the 1Wire bus. This device calls itself 1013878a02080098 in my case.

Internals

RTC RAM Slots

• Slots 0 - 9 are used by the RTC itself
• Slots 10 - 20 are used by the RTC fifo for metadata
• Slots 21 - 31 are unused
• Slots 32 - 128 are used by the RTC fifo for its journal