initial commit

Author: Jimmy Bradshaw

Makefile

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+NAME := lua-interpreter
+PORT := /dev/cu.SLAB_USBtoUART
+NODEMCU_BIN := nodemcu-master-11-modules-2020-04-22-14-23-50-integer.bin
+
+.PHONY: help
+help:
+	@grep -E '^[a-zA-Z_-]+:.*?## .*$$' $(MAKEFILE_LIST) | sort | awk 'BEGIN {FS = ":.*?## "}; {printf "\033[36m%-30s\033[0m %s\n", $$1, $$2}'
+
+.PHONY: flash
+flash: ## flash nodemcu
+	esptool.py --port $(PORT) erase_flash
+	esptool.py --port $(PORT) write_flash --flash_mode dio 0x00000 $(NODEMCU_BIN)
+	sleep 5
+	nodemcu-tool -p $(PORT)  mkfs --noninteractive
+
+.PHONY: init
+init: ## upload init file
+	nodemcu-tool -p $(PORT) upload init.lua
+
+.PHONY: term
+term: ## start terminal
+	nodemcu-tool -p $(PORT) terminal

README.md

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+# nodemcu-mqtt-lua-interpreter
+
+Use mqtt to pass chunks to be interpreted, allows for responses on another topic.
+
+## Getting Started
+
+### Setup
+
+Requires [esptool](https://github.com/espressif/esptool) and [nodemcu-tool](https://github.com/andidittrich/NodeMCU-Tool).
+
+Modify `Makefile` with your serial port
+
+Modify `init.lua` with your MQTT host.
+
+`make flash` to flash nodemcu
+
+`make init` to upload the lua init script
+
+`make term` to start a lua terminal
+
+### Usage
+
+Send a mqtt message to be interpreted, e.g.
+
+`mosquitto_pub -h <host> -t /lua-interpreter -m '{"chunk": "gpio.mode(1, gpio.OUTPUT) gpio.write(1, gpio.HIGH)}'`
+
+which will configure pin 1 in output mode and set it high.
+
+If a reply is desired, you can pass a "reply-to" key in the JSON payload, e.g.
+
+mosquitto_sub -h <host> -t /lua-interpreter
+
+and then in another shell
+
+mosquitto_pub -h <host> -t /lua-interpreter -m '{"chunk": "return gpio.read(1)", "reply-to": "/reply"}'
+
+which will read pin 1 (should be 1 now) and we receive that response on the /reply topic.

init.lua

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+mqtthost = "192.168.0.108"
+interpretername = "lua-interpreter"
+interpretertopic = "/" .. interpretername
+
+function interpret(client, topic, data)
+    print("message on " .. topic .. " with body " .. data)
+    if topic == interpretertopic and data ~= nil then
+        print("interpreting message")
+        local req_t = sjson.decode(data)
+        local status, val = pcall(loadstring(req_t["chunk"]))
+        if status then
+            print("interpreting successful")
+        end
+        local replyto = req_t["reply-to"]
+        if replyto ~= nil then
+            resp_t = {success=status, message=val}
+            resp_json = sjson.encode(resp_t)
+            print("publishing to " .. replyto .. " with " .. resp_json)
+            client:publish(replyto, resp_json, 0, 0, function () print("publish success") end)
+        end
+    end
+end
+
+function onconnect(client)
+    client:subscribe(interpretertopic, 0, function () print("subscribe success") end)
+end
+
+function mqttsetup()
+    local client = mqtt.Client(interpretername, 120)
+    client:on("message", interpret)
+    client:connect(mqtthost, 1883, false, function ()
+        print("connect success")
+        onconnect(client)
+    end,
+    function (_, reason)
+        print('connect failed reason: ' .. reason)
+    end
+    )
+end
+
+function wificheck(timer)
+    if wifi.sta.status() == wifi.STA_GOTIP then
+        print('wifi connected')
+        timer:unregister()
+        mqttsetup()
+    else
+        print('wifi not connected...')
+        timer:start()
+    end
+end
+
+function init()
+    inittimer = tmr.create()
+    inittimer:alarm(1000, tmr.ALARM_SEMI, wificheck)
+end
+
+init()