Sending OTA updates over WiFi to your ESP8266

This Christmas, I added a whole bunch of lights powered by 5V power sources. My goal was to switch them on at sunset, and switch them off on sunrise, by using a MOSFET for power control :)

While I was doing this, I wanted to send OTA updates of my Lua files to the ESP8266 via WiFi. For some unknown reason, I couldn’t use luatool.py’s TCP update method.

So, I ended up building my very own OTA update protocol (which turned out to be fun!). To begin, add ota.lua to your project, and invoke it using dofile("ota.lua") in your init.lua:

Send OTA updates to remotely update lua scripts on your ESP8266.
LICENCE: http://opensource.org/licenses/MIT
Created by Jude Pereira <contact@judepereira.com>
See https://judepereira.com/blog/sending-ota-updates-over-wifi-to-your-esp8266/
srv = net.createServer(net.TCP)
current_file_name = nil
srv:listen(8080, function(conn)
conn:on("receive", function(sck, payload)
if string.sub(payload, 1, 5) == "BEGIN" then
current_file_name = string.sub(payload, 7)
file.open(current_file_name, "w")
file.close()
sck:send("NodeMCU: Writing to " .. current_file_name .. '\n')
elseif string.sub(payload, 1, 4) == "DONE" then
sck:send("NodeMCU: Wrote file " .. current_file_name .. "!\n")
current_file_name = nil
elseif string.sub(payload, 1, 7) == "RESTART" then
sck:send("NodeMCU: Restart!\n")
tmr.create():alarm(500, tmr.ALARM_SINGLE, node.restart)
else
if file.open(current_file_name, "a+") then
if file.write(payload) then
file.close()
sck:send("ok\n")
else
sck:send("NodeMCU: Write failed!\n")
end
else
sck:send("NodeMCU: Open failed!\n")
end
end
end)
conn:on("sent", function(sck) sck:close() end)
end)
view raw ota.lua hosted with ❤ by GitHub

Then, to use this shiny new TCP endpoint created on your ESP8266/NodeMCU, create a wrapper shell script:

#!/bin/bash
# Wrapper script for sending OTA updates to your ESP8266 running NodeMCU.
# See https://judepereira.com/blog/sending-ota-updates-over-wifi-to-your-esp8266/
HOST=192.168.178.25
PORT=8080
for i in "$@"; do
FILE=$i
echo "Sending $i"
echo -n "BEGIN $FILE" | nc $HOST $PORT
while read -r line; do
#echo -n "write: $line … "
if ! echo "$line" | nc $HOST $PORT | grep "ok" &>/dev/null; then
echo "Write failed! Please retry…"
exit 1
fi
done <"$FILE"
echo -n "DONE" | nc $HOST $PORT
done
echo -n "RESTART" | nc $HOST $PORT
view raw ota.sh hosted with ❤ by GitHub

Heads up! Replace HOST with the IP of your NodeMCU.

The wrapper script will automatically trigger a restart at the end. To use the wrapper script:

$ chmod +x ota.sh
$ ./ota.sh file1.lua file2.lua init.lua

And that’s it! OTA update away!

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