Update DS18b20 examples (#1851)

- Remove old non-async examples from `lua-examples`.
- Rename `ds18b20.EN.md` to `README.md`
- Change remaining `toBase64` calls to the more standard `toHex` call.
- Fix some spelling and markdown formatting issues in README file.

Addresses issue #1841

lua_examples/onewire-ds18b20.lua

@@ -1,76 +0,0 @@
---'
--- ds18b20 one wire example for NODEMCU (Integer firmware only)
--- NODEMCU TEAM
--- LICENCE: http://opensource.org/licenses/MIT
--- Vowstar <vowstar@nodemcu.com>
---' 
-
-pin = 9
-ow.setup(pin)
-count = 0
-repeat
-  count = count + 1
-  addr = ow.reset_search(pin)
-  addr = ow.search(pin)
-  tmr.wdclr()
-until((addr ~= nil) or (count > 100))
-if (addr == nil) then
-  print("No more addresses.")
-else
-  print(addr:byte(1,8))
-  crc = ow.crc8(string.sub(addr,1,7))
-  if (crc == addr:byte(8)) then
-    if ((addr:byte(1) == 0x10) or (addr:byte(1) == 0x28)) then
-      print("Device is a DS18S20 family device.")
-        repeat
-          ow.reset(pin)
-          ow.select(pin, addr)
-          ow.write(pin, 0x44, 1)
-          tmr.delay(1000000)
-          present = ow.reset(pin)
-          ow.select(pin, addr)
-          ow.write(pin,0xBE,1)
-          print("P="..present)  
-          data = nil
-          data = string.char(ow.read(pin))
-          for i = 1, 8 do
-            data = data .. string.char(ow.read(pin))
-          end
-          print(data:byte(1,9))
-          crc = ow.crc8(string.sub(data,1,8))
-          print("CRC="..crc)
-          if (crc == data:byte(9)) then
-             t = (data:byte(1) + data:byte(2) * 256)
-
-             -- handle negative temperatures
-             if (t > 0x7fff) then
-                t = t - 0x10000
-             end
-
-             if (addr:byte(1) == 0x28) then
-                t = t * 625  -- DS18B20, 4 fractional bits
-             else
-                t = t * 5000 -- DS18S20, 1 fractional bit
-             end
-
-             local sign = ""
-             if (t < 0) then
-                 sign = "-"
-                 t = -1 * t
-             end
-
-             -- Separate integral and decimal portions, for integer firmware only
-             local t1 = string.format("%d", t / 10000)
-             local t2 = string.format("%04u", t % 10000)
-             local temp = sign .. t1 .. "." .. t2
-             print("Temperature= " .. temp .. " Celsius")
-          end                   
-          tmr.wdclr()
-        until false
-    else
-      print("Device family is not recognized.")
-    end
-  else
-    print("CRC is not valid!")
-  end
-end

lua_examples/yet-another-ds18b20.lua

@@ -1,73 +0,0 @@
-------------------------------------------------------------------------------
--- DS18B20 query module
---
--- LICENCE: http://opensource.org/licenses/MIT
--- Vladimir Dronnikov <dronnikov@gmail.com>
---
--- Example:
--- dofile("ds18b20.lua").read(4, function(r) for k, v in pairs(r) do print(k, v) end end)
-------------------------------------------------------------------------------
-local M
-do
-  local bit = bit
-  local format_addr = function(a)
-    return ("%02x-%02x%02x%02x%02x%02x%02x"):format(
-        a:byte(1),
-        a:byte(7), a:byte(6), a:byte(5),
-        a:byte(4), a:byte(3), a:byte(2)
-      )
-  end
-  local read = function(pin, cb, delay)
-    local ow = require("ow")
-    -- get list of relevant devices
-    local d = { }
-    ow.setup(pin)
-    ow.reset_search(pin)
-    while true do
-      tmr.wdclr()
-      local a = ow.search(pin)
-      if not a then break end
-      if ow.crc8(a) == 0 and
-        (a:byte(1) == 0x10 or a:byte(1) == 0x28)
-      then
-        d[#d + 1] = a
-      end
-    end
-    -- conversion command for all
-    ow.reset(pin)
-    ow.skip(pin)
-    ow.write(pin, 0x44, 1)
-    -- wait a bit
-    tmr.alarm(0, delay or 100, 0, function()
-    -- iterate over devices
-      local r = { }
-      for i = 1, #d do
-        tmr.wdclr()
-        -- read rom command
-        ow.reset(pin)
-        ow.select(pin, d[i])
-        ow.write(pin, 0xBE, 1)
-        -- read data
-        local x = ow.read_bytes(pin, 9)
-        if ow.crc8(x) == 0 then
-          local t = (x:byte(1) + x:byte(2) * 256)
-          -- negatives?
-          if bit.isset(t, 15) then t = 1 - bit.bxor(t, 0xffff) end
-          -- NB: temperature in Celsius * 10^4
-          t = t * 625
-          -- NB: due 850000 means bad pullup. ignore
-          if t ~= 850000 then
-            r[format_addr(d[i])] = t
-          end
-          d[i] = nil
-        end
-      end
-      cb(r)
-    end)
-  end
-  -- expose
-  M = {
-    read = read,
-  }
-end
-return M

lua_modules/ds18b20/README.md

@@ -11,17 +11,17 @@ package.loaded["ds18b20"]=nil
 <a id="ds18b20_setup"></a>
 
 ## readTemp()
-Scans the bus for DS18B20 sensors, starts a readout (conversion) for all sensors and calls a callback function when all temperatures are available. Powered sensors are read at once first. Parasit-powered sensors are read one by one. The first parasit-powered sensor is read together with all powered sensors.
+Scans the bus for DS18B20 sensors, starts a readout (conversion) for all sensors and calls a callback function when all temperatures are available. Powered sensors are read at once first. Parasite-powered sensors are read one by one. The first parasite-powered sensor is read together with all powered sensors.
 
 The module requires `ow` module.
 
-The also module uses `encoder` module for printing debug information with more readable representation of sensor address (`encoder.toBase64()`).
+The also module uses `encoder` module for printing debug information with more readable representation of sensor address (`encoder.toHex()`).
 
 #### Syntax
 `readTemp(callback, pin)`
 
 #### Parameters
-- `callback` function that receives all results when all conversions finish. The callback funciton has one parameter - an array addressed by sensor addresses and a value of the temperature (string for integer version).
+- `callback` function that receives all results when all conversions finish. The callback function has one parameter - an array addressed by sensor addresses and a value of the temperature (string for integer version).
 - `pin` pin of the one-wire bus. If nil, GPIO0 (3) is used.
 
 #### Returns
@@ -34,7 +34,7 @@ pin = 3 -- gpio0 = 3, gpio2 = 4
 
 function readout(temp)
   for addr, temp in pairs(temp) do
-    print(string.format("Sensor %s: %s 'C", encoder.toBase64(addr), temp))
+    print(string.format("Sensor %s: %s 'C", encoder.toHex(addr), temp))
   end
 
   -- Module can be released when it is no longer needed
@@ -48,7 +48,7 @@ if t.sens then
   print("Total number of DS18B20 sensors: "..table.getn(t.sens))
   for i, s in ipairs(t.sens) do
     -- print(string.format("  sensor #%d address: %s%s", i, s.addr, s.parasite == 1 and " (parasite)" or ""))
-    print(string.format("  sensor #%d address: %s%s",  i, encoder.toBase64(s.addr), s.parasite == 1 and " (parasite)" or "")) -- readable address with base64 encoding is preferred when encoder module is available
+    print(string.format("  sensor #%d address: %s%s",  i, encoder.toHex(s.addr), s.parasite == 1 and " (parasite)" or "")) -- readable address with Hex encoding is preferred when encoder module is available
   end
 end
 ```

lua_modules/ds18b20/ds18b20-web.lua

@@ -12,7 +12,7 @@ function readout(temp)
 
   for addr, temp in pairs(temp) do
     -- resp = resp .. string.format("Sensor %s: %s &#8451</br>", addr, temp)
-    resp = resp .. string.format("Sensor %s: %s &#8451</br>", encoder.toBase64(addr), temp) -- readable address with base64 encoding is preferred when encoder module is available
+    resp = resp .. string.format("Sensor %s: %s &#8451</br>", encoder.toHex(addr), temp) -- readable address with base64 encoding is preferred when encoder module is available
   end
 
   resp = resp ..