From 17f08c2048eefa90fd5f4b2ffafae67df0496cc1 Mon Sep 17 00:00:00 2001
From: Nathaniel Wesley Filardo <nwf@cs.jhu.edu>
Date: Thu, 14 Dec 2017 16:18:58 -0500
Subject: [PATCH] Store configuration to RTC memory, too

---
 README.rst     |  6 +++++-
 init3.lua      |  6 +-----
 thermostat.lua | 35 ++++++++++++++++++++++++++++++++++-
 3 files changed, 40 insertions(+), 7 deletions(-)

diff --git a/README.rst b/README.rst
index 113b3da..fb591fa 100644
--- a/README.rst
+++ b/README.rst
@@ -142,7 +142,11 @@ 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
+* Slot  22 used by thermostat itself and holds
+  * bits 0-7 : target value
+  * bits 8-9 : operating mode
+  * bit  10  : fan drive
+* Slots 23 - 31  are unused
 * Slots 32 - 128 are used by the RTC fifo for its journal
 
 
diff --git a/init3.lua b/init3.lua
index 7947861..da5361c 100644
--- a/init3.lua
+++ b/init3.lua
@@ -10,10 +10,6 @@ mqttPubRoot    = "lcn/therm/"
 -- modules
 nwfnet = require "nwfnet"
 mqc, mqcu = dofile("nwfmqtt.lc").mkclient("nwfmqtt.conf")
-
--- rtcfifo conditional init
-if rtcfifo.ready() == 0 then rtcfifo.prepare() end
-
 mqc:lwt(mqttHeartTopic,"dead",1,1)
 
 -- setup peripherals
@@ -66,7 +62,7 @@ end
 function logdata(v,e,n)
   local t = rtctime.get()
   if mqtt_reconn_timer == nil then mqc:publish(mqttPubRoot..n,sjson.encode({ ['t']=t, ['v']=v, ['e']=e }),1,1) end
-  if v then rtcfifo.put(t,v,e,n) end
+  if rtcfifo.ready() and v then rtcfifo.put(t,v,e,n) end
 end
 
 -- go online
diff --git a/thermostat.lua b/thermostat.lua
index ede1804..ccc1c0e 100644
--- a/thermostat.lua
+++ b/thermostat.lua
@@ -6,11 +6,43 @@ local tcPollIval = 9000   -- + 1 second for 1w read, too
 local tcVWin     = 10     -- longest sliding sampling window
 local tcFOffDly  = 180000 -- run the fan after turning of H/AC
 
--- remote configuration (set by MQTT)
+-- remote configuration (set by MQTT or rtcmem, below)
 local tctarget   = 55
 local tcmode     = "off" -- "off" "cool" "heat" "emht"
 local tcfan      = false -- should we keep the fan on?
 
+local function storeconfig()
+  local v
+  -- are you kidding?
+  if     tctarget < 0   then v = 0
+  elseif tctarget > 255 then v = 255
+  else                       v = tctarget
+  end
+
+  if     tcmode == "cool" then v = bit.bor(v, 0x00000100)
+  elseif tcmode == "heat" then v = bit.bor(v, 0x00000200)
+  elseif tcmode == "emht" then v = bit.bor(v, 0x00000300)
+  end
+
+  if tcfan then v = bit.bor(v, 0x00000400) end
+
+  rtcmem.write32(21, v)
+end
+
+-- rtcfifo conditional init
+if rtcfifo.ready() == 0 then
+  rtcfifo.prepare()
+  storeconfig()
+else
+  -- the rtc is good to go, so we must have valid configuration
+  -- in rtcmem.  Fetch and decode.
+  local w = rtcmem.read32(21)
+  tctarget =             bit.band(w, 0x000000FF)
+  tcfan    = not (0 ==   bit.band(w, 0x00000400))
+  local m  = bit.arshift(bit.band(w, 0x00000300),8)
+  tcmode = ({ "off", "cool", "heat", "emht" })[m+1]
+end
+
 -- state
 local driving          = false -- are we driving?
 local fanOffDelayTMR   = nil   -- a timer for nixing the fan
@@ -95,6 +127,7 @@ nwfnet.onmqtt["th"] = function(c,t,m)
   else   return -- not for us?
   end
 
+  storeconfig()
   doRelays()
 end
 
-- 
2.50.1