Ask Google for the time with an ESP8266

This is an example of how to connect to Google and retrieve just the HEAD information, which happens to include the current time.

It would be possible to do this with NTP, but that would require more coding. The results wouldn’t be any more accurate. I am pretty sure Google keeps the time on their servers well synchronized with the actual time.

— retrieve the current time from Google
— tested on NodeMCU 0.9.5 build 20150108

conn=net.createConnection(net.TCP, 0)

conn:on(“connection”,function(conn, payload)
conn:send(“HEAD / HTTP/1.1\r\n”..
“Host: google.com\r\n”..
“Accept: */*\r\n”..
“User-Agent: Mozilla/4.0 (compatible; esp8266 Lua;)”..
“\r\n\r\n”)
end)

conn:on(“receive”, function(conn, payload)
print(‘\nRetrieved in ‘..((tmr.now()-t)/1000)..’ milliseconds’)
print(‘Google says it is ‘..string.sub(payload,string.find(payload,”Date: “)
+6,string.find(payload,”Date: “)+35))
conn:close()
end)
t = tmr.now()
conn:connect(80,’google.com’)

The program can be saved to a file, google.lua. Then, dofile(‘google.lua’) will retrieve and print the time. From this location, the normal elapsed time from requesting to printing was under one tenth of a second. Pretty good.

Simple scripts like this are easy to enter and test with LuaLoader.

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Tags: esp8266, IoT, Lua, NodeMCU