After the article about the connection with the temperature and humidity sensor
MQTT with BeagleBone and ESP8266 – MQTT on ESP8266 with temperature sensor
in this article we set the esp8266 to run a relay. Here is how we connect the relay to the ESP module
In this example too we will consider the option of putting the nodemcu in sleep. To have the node back form the sleep the system has to reboot and it is necessary to connect the PIN D0 (GPIO16) to RST PIN as specified in the nodemcu documentation
Let us take a look at the lua code; It consists of init.lua and relay.lua files.
We analyze now the main points of each file
- init.lua
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 |
-- init.lua SSID="SSID" -- SSID PASSWORD="password" -- SSID password TIMEOUT=10000 -- timeout to check the network status EXSENSOR1="relay.lua" -- module to run MQTTSERVER="mqttaddress" -- mqtt broker address MQTTPORT="1883" -- mqtt broker port MQTTQOS="0" -- qos used -- Set the netowrk parameters and get ip address wifi.setmode(wifi.STATION) wifi.sta.config(SSID, PASSWORD) wifi.sta.getip() -- Check the network status after the TIMEOUT interval tmr.alarm(0, TIMEOUT,tmr.ALARM_SINGLE, function() status=wifi.sta.status() -- if esp8266 got the ip if (status == wifi.STA_GOTIP ) then dofile(EXSENSOR1) else -- Without up restart the node print("Error acquiring ip address=",status) node.restart() end end ) |
In the file we set the the parameters to access the wifi network, the address and port of the MQTT broker and the file to be run on the ESP after wifi connection to the access point is estabilished. If the ESP doesn’t acquire the network address the system is restarted.
- relay.lua
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 |
-- relay.lua CNAME="relay1" -- Client name AMBIENT="home" -- Ambient name STOPIC = AMBIENT.."/"..CNAME.."/status" -- Status topic CTOPIC = AMBIENT.."/"..CNAME.."/command" --Command topic MTOPIC = AMBIENT.."/"..CNAME.."/monitor" --Monitor topic sleep_in_seconds= nil --Sleep in seconds TUPDATE = 20 -- Time interval for update monitor in seconds RPIN =1 -- Relay Pin TGEN = 5 -- Time interval in seconds usend in various trm gpio.mode(RPIN,gpio.OUTPUT) -- Set Relay pin mode gpio.write(RPIN,gpio.LOW) -- Default output is OFF -- Define Client Name and connection parameters mqt = mqtt.Client(CNAME, 60, "", "", 1) -- Subscribe to the topics and send status to the status topic mqt:on("connect", function() mqt:subscribe(STOPIC, MQTTQOS) mqt:subscribe(CTOPIC, MQTTQOS) mqt:subscribe(MTOPIC, MQTTQOS) send_status("Relay ready again") end ) -- Callback when mqtt is offline mqt:on("offline", function() print("mqtt offline"); end) --Callback to manage messages mqt:on("message", function(client, topic, data) manage_message(client, topic, data) end) -- Function to filter the messages function manage_message(client, topic, data) -- If CTOPIC: command topic if topic == CTOPIC then -- If the command is Restart if data == "Restart" then send_status("Restarting") send_mstatus("Restarting") tmr.alarm(2, TGEN*1000, tmr.ALARM_SINGLE, node.restart) -- If the command is null elseif data == nil then send_status("Command not valid") -- Command to turn on the Relay elseif data == "ON" then relay_on() -- Command to turn off the Relay elseif data == "OFF" then relay_off() -- Command to check the state of the Relay elseif data == "Status" then relay_status() else -- Check the Sleep command i=string.len(data) dato=string.sub(data,1,5) if dato == "Sleep" then ndato=string.sub(data,6) TSLEEP=tonumber(ndato) if TSLEEP ~= nil then if TSLEEP >= 1 then -- Sets the interval in seconds to sleep sleep_in_seconds=TSLEEP*60 esp_sleep() else -- Send an error in Sleep command send_status("Sleep command error") end else -- Send an error in Sleep command send_status("Sleep command error") end else -- Command not managed send_status("Command not valid") end end end end -- Function to turn on the relay function relay_on() gpio.write(RPIN,gpio.HIGH) send_status("Relay ON") end -- Function to turn off the relay function relay_off() gpio.write(RPIN,gpio.LOW) send_status("Relay OFF") end -- Function to check if the the relay is on or off function relay_status() risultato=gpio.read(RPIN) if(risultato==1) then send_status("Relay ON") elseif(risultato==0) then send_status("Relay OFF") end end -- Function to send messages to to STOPIC: status topic function send_status(message) mqt:publish(STOPIC, message, MQTTQOS, 0) end -- Fucntion to send messages to MTOPIC: monitor topic function send_mstatus(message) mqt:publish(MTOPIC, message, MQTTQOS, 0) end -- Function that sleeps esp8266 function esp_sleep() send_status("Relay going to sleep now") send_mstatus("Relay going to sleep now") -- Delayd sleep to send the message above. tmr.alarm(3, TGEN*1000, tmr.ALARM_SINGLE, function() node.dsleep(sleep_in_seconds*1000000) end) end -- Connection to the mqtt server at the msttport mqt:connect(MQTTSERVER, MQTTPORT, 0, 1) -- Send periodically a message to the monitor topic tmr.alarm(4, TUPDATE*1000, tmr.ALARM_AUTO, function() send_mstatus("Relay Ready") end) |
The relay.lua file manages the relay, the subscription on MQTT broker with submission of the data. Global parameters have been set to manage the topic, the waiting time in tmr.alarm. There are in particular the following topics
- /home/relay1/status : Status topic. The status is sent at the start and at request from the command topic /home/relay1/command.
- /home/relay1/monitor: Status of the esp sent periodically to this topic.
- /home/relay1/command: Other clients can send commands to the esp:
- Restart: Restarts the esp.
- Sleep n: Put to sleep for n seconds the esp.
- ON: Turn on the relay.
- OFF: Turn off the relay.
- Status: Request of tthe relay status (ON or OFF).
There are various service functions to manage all. The comments in the code describe each feature.
In the next article we will set up the webserver on Beaglebone and the websocket configuration for Mosquitto always on the Beaglebone
MQTT with BeagleBone and ESP8266 – WebServer and MQTT WebSocket