MM Defender IOT Controller Add-On Construction Details

This is a rather large topic under construction. Current progress is about 70%.

Recent posts on the Mosquito Magnet Forum have described a replacement controller that a skilled DIY (Do It Yourself) person can build and install. Poor manufacturing quality control plus harsh outdoor environments has caused some original controllers becoming faulty with age. Additionally, it is quite difficult for DIYers with technical expertise to troubleshoot a non-working trap with just the original controller, even with troubleshooting instruments. What is missing is a mechanism to monitor and troubleshoot these devices so they can keep working into the future. The MM Defender IOT Controller article describes an effective approach, but is lacking details on how to actually construct and implement the device. This article will supply more details. It is, however, necessary to discuss a few matters regarding this MM Defender IOT Controller Add-On design, which partially explains why this topic was not written earlier.

Hazard Warning

First, the Mosquito Magnet traps use propane gas, which is flammable, and therefore dangerous. The original trap designers took great pains to make sure the trap would be safe. This is why the trap shuts down if everything is not "just so." While frustrated users being bitten might say that the trap is overly conservative and unnecessarily cautious, DIYers have not done the extensive analysis customary for a manufacturer of a potentially dangerous device.

Making and deploying a substitute controller, or any modification of a dangerous device, can be regarded as a risky or even reckless action. If something goes wrong, and there is an explosion, poisoning, or other calamity resulting in loss of life and limb, or property damage, do you want to have had a hand in the chain of events that possibly or even arguably might have caused it?

Second, the construction, modification, and installation requires tools and instruments plus experience with PCBs and micro component soldering. Those without the right tools or skills will find this project too difficult. Once modified, it is relatively easy but not trivial to revert to the original controller. If the modified system does not work, you may be stuck.

This design is an Add-On to the original controller. Accordingly, other than the original PIC micro-controller, the original controller must be working because the IOT Controller Add-On just substitutes for the PIC. However, it is the failure of some of the parts of the original controller that might have caused the problem in the first place, and fixing those issues could restore the original controller to functionality. If the trap still does not work reliably, capable experts willing to assume the risk might choose to use the add-on controller to help identify those issues.

Third, the controller is an experimental device intended for use by experts to troubleshoot a non-working trap, and not as a permanent replacement for the original controller. As presently implemented, it lacks important features required for a permanent deployment. Some of these are: adequate mechanical support (mounting to the device), weatherproofing, and, of course, safety and functionality certification and validation.

Currently, the controller is supported only by the wires connecting it to the original controller PCB. Because it is not fully insulated, it must be positioned just so to avoid shorting to the trap metal parts. Although electrical insulation and some weatherproofing could be mostly jury-rigged by covering the controller with a plastic bag, this is not a permanent solution. This unprotected device does not and will not survive condensation and contamination from the elements.

Although wireless remote control makes physical contact with the device unnecessary, as an experimental device, it is desirable for it to be quickly and easily accessible for updating or substitution. This requires removing the catch basket and top cover. It is not easy to remove the top cover screws, so to avoid biting mosquitos, some may choose leave the screws out, which then results in yet another potential hazard.

Under no circumstances do we want anyone to endanger any life or property. Any servicing or modification of the trap is a dangerous undertaking. You should label any modified trap with a warning.

Remember, the add-on will not work reliably over the months or years due to lack of mechanical support and weatherproofing. Once your trap is working reliably, you should uninstall the controller add-on and revert to the original, unless you are engaged in active development, are willing to assume the risks, and willing to maintain and repair the modification as it corrodes or otherwise deteriorates.

These remarks, of course, apply to all DIY modifications, not just this one, which is intended only for troubleshooting and development. Finally, please be cautious, even if you improve upon the design.

Photos

Nothing to be too proud of here. Some burned insulation, scattered wires, no strain relief anywhere. Click on a picture to see it larger.

Loose placement of IOT Controller Add-On with optional Temp/Humidity sensor
Controller with NodeMCU and Temp/Humidity attached
Front (or right hand side) view of IOT Controller Add-On showing 15 pin header wiring
Rear (or left hand side) view of IOT Controller Add-On showing power and thermistor connections
Placement of IOT Controller Add-On Wires on Original PCB.

There are 10 wires connecting the Add-On headers to the original controller, and 4 more connecting to the optional Temperature/Humidity sensor, which itself is flying off the Add-On. Nice work! Observe the lack of strain relief and mechanical support, other than the 10 wires. This hack job is dis-recommended for long-term use. Note how easily the NodeMCU module or its uninsulated pins can come into contact with the metal trap parts. Be careful, or insulate, mount somehow, or all three.

Generally, the connecting wires are soldered to the most rugged attachment points available, through hole terminals if available, or soldered to a component and its pad if not. However, 2 wires are soldered only to pads, and these are fragile. Some notes:

C4 is effectively removed by cutting the foil to it (to the right of the middle white wire, a bit hard to see)
On the board, the PIC controller has been completely removed (because it was fried). Otherwise, unsolder and lift pin 4 from its pad on +5v, and solder a very thin 1 strand jumper between the lifted pin and the adjacent pin #5. This sets the MCLR/ signal low, which effectively disconnects the PIC.
Note the jumper between pin 14 and the top of R5 or pin 11. This connects VDD to R5 20k0.
VDD is disconnected from +5v by cutting a foil on the bottom of the PCB (not shown).
VDD is connected to +3.3v from the NodeMCU via the left orange wire.
The right hand white and orange wires connect to the original ground and +5v rails near the electrolytic cap. These go to the rear or left hand side connector pins.
The single pin white wire connects the ADC input to the bottom of R5.
The WiFi antenna is on the front of the NodeMCU, and the USB connector is on the back. There is also a reset and a flash button, and 2 status LEDs.

Basic Steps

Thoroughly read the MM Defender Controller and MM Defender IOT Controller wiki pages.
#Assemble Tools and Supplies
#Test and Fix the Original Controller
#Acquire Materials
#Set up Development PC & Software
#Attach Header Pins to the HTU-21D
#Program and Test Module(s)
#Build the Wiring Harness
#Modify the Controller PCB
#Attach the Harness
#Initial Test Outside Trap
#Install Modified Controller into Trap
#Move Trap to Operating Location
#Final Test
#Monitor from PC and Phone

Assemble Tools and Supplies

You will need the following tools, equipment, and supplies:

10x (opt. plus 50x) Stereo Microscope with illumination to clearly see what you are doing.
Soldering iron with micro tip.
Solder and solder flux
Fine solder wick, PCB cleaner, isopropyl alcohol, and brushes for cleaning.
Contact cleaner for switches and connectors (e.g., DeOxit).
Brush on conformal coating (e.g., MG Electronics 4223 (urethane) or 422B (silicone))
Micro tweezers for surface mount device (SMD) placement and manipulation.
A fine gauge (diabetes) medical syringe is helpful for prying and scraping.
Volt-Ohm Meter (VOM) with suitable test leads.
Clip leads for testing, plus a 1k or so resister for forcing the driver transistors on.
Oscilloscope, single or dual channel, calibrated, with probes. 10 MHz or higher. 1 MHz might work with allowances, not tested.
Diagonal cutters and wire stripper for fine (e.g., 24-32) gauge stranded wire.

Test and Fix the Original Controller

If the original controller is not working, or even if it is, it is a good idea to remove it, clean it, and inspect it thoroughly.

The 3 standoffs holding the board will have become brittle with age. Be careful when removing the board from the standoffs, and press the release tab on the component side before very gently pulling the board out. If you break a standoff, you can replace it (Richco SCBS-16-01), or tap the body for an 8-32 stud. The same goes for the nylon thermistor bolt, it should be replaced every service time (8-32 x 1/2").

The PCB is lightly (inadequately) sealed with a sealer for weatherproofing. Accordingly, you have to scrape off the sealant to probe a pad.

Measure the resistances of the fan (?? Ohms, although it either works or it doesn't), igniter (0.9 - 1.4 Ohms), solenoid (?? Ohms), and thermistor (200 kOhms). If these are either too low or too high, they must be replaced.
Measure the resistance across C4. Disconnect the thermistor. Attach the VOM negative lead to the negative (ground) terminal of power supply filter cap C2 (large 3300 uF @ 25v) and the positive lead to J1 terminal 1. The resistance should be in the meg-Ohm range (this is from the PIC). If it is low (e.g., 20 kOhms), your controller is suffering from the "C4 PCB contamination" issue discussed on the controller wiki page. If low,
- Carefully unsolder C4 (ca 120 nF ceramic, was previously marked 150 nF). Remove the coating from the PCB in the vicinity of the pads. Thoroughly clean the PCB between the pads. Measure the resistance again until it is in the meg-Ohm range. Measure C4, then carefully strip and clean as necessary until infinite resistance is obtained. Build up a solder blob on each mounting pad. Solder C4 to the blob to allow space underneath for cleaning. Thoroughly clean and measure. When in the meg-Ohm range, seal the area with a conformal coating. Use two coats. Very critical, and a major reason the original units failed.
With the 'scope, measure the power supply voltages and ripple voltages. See that the ripples are symmetrical, and not too large for the D1 C2 +20v supply. The large bridge rectifier D2 has no filter cap, and will show all ripples. Attach the igniter and ground the J5 pin 2 lead to power the igniter, and see that the voltage does not just collapse. The RMS value should be appropriate for the 12 volts igniter. The igniter should light up, and be hot enough to ignite a propane torch. This also tests the power supply and long low voltage cord. If there is a problem with insufficient power, check the AC side of the supply to isolate the problem to the supply/cord or D2 rectifier bridge.
Measure the +12 and +5v rails, they should be without ripple.
Attach the fan, thermistor, switch, and gas valve solenoid. Power the unit again, and observe the low (ground) side of the Igniter, Fan, and Valve go from +12 to 0 volts as the driver transistors switch on. Check the switch LED to see that it flashes on power up.

If any of these tests fail, there is a problem with either the driver transistors, the controller, or the switch that must be fixed before the IOT Controller Add-On can be used.

Check the switch terminal to see that it goes between +5v (off) and ground (on) when actuated. Make sure that wiggling the wires to the switch has no effect in either position.
Use the 1 kOhm or so resister in series with a test lead connected to +5v rail (supply voltage) to test the driver transistors. (You may have to scrape a pad on (e.g., on C7) and possibly solder a small piece of solid wire to access this rail.). Measure the voltage across the fan, igniter, and valve terminals to see that it goes on when the 1 kOhm signal is applied to the gate or base of the driver transistors. If not, the driver is defective, or possibly the igniter, fan, or valve solenoid is shorted.

If these tests are passed, perhaps you have fixed the problem, and can use your trap as is, provided the controller works. Try it. If working, catch some mosquitos and stop here. If not, you can continue with the IOT Controller Add-On.

Acquire Materials

Per unit, the NodeMCU is about $6, the optional HTU21D is ~$4, and the header, the wires, and the heat shrink tubing are hopefully "lying around" somewhere. Of course, you will want to buy multiples.

1 or more ESP8266 ESP-12E NodeMCU modules, from any number of vendors, e.g., "MakerFocus ESP8266 NodeMCU LUA CP2102 ESP-12E Internet WiFi Development Board Serial Wireless Module." Cost about $12 for 2 (get 4).
(optional) 1 or more HTU21D Temperature/Humidity module, e.g., "HiLetgo HTU21D Temperature Humidity Sensor Breakout Module I2C IIC 1.5V-3.6V." Cost about $7 for 2.
1 40 pin female header strip, e.g., "10 Pcs 40 Pin 2.54mm Pitch Straight Single Row PCB Female Pin Headers." You should already have these, but the cost of about $6 for 10 pieces, yields a lifetime supply.
Several colors of thin (28-32) gauge, stranded, flexible, 200°C, very high quality hookup wire with high temperature PTFE or Teflon insulation, e.g., "Alpha 2840/7." This example uses white, red, blue, orange, yellow, violet, and brown. Try to "borrow" the short lengths of wire from a "friend," otherwise it could get expensive (e.g., $70 for 100' reel, each color) to buy wire for this project.
- Do not use stiff or cheap wire. It will break with handling, melt, or tear the PCB board. The colored wire in flat cable may be tempting, but is especially unsuitable. If you do use stiff wire, it must be well strain-relieved on both the PCB and header ends.
Heat shrink tubing is useful for insulating the terminals on the rear or left hand side of the module.

Set up Development PC & Software

The most convenient tools are java apps. Also, there is a python module that downloads the lua environment (OS with optional function modules) onto a new NodeMCU.

Install Java, if not installed.
Connect the ESP-12E Module to the PC via USB. If necessary, install the CP2102 Drivers to create a new COM port.
Download and install ESPlorer, a java Integrated Development Environment (IDE) for ESP8266 developers.
Download and install mqtt-spy, a java MQTT client.
Download NodeMCU Flasher for Windows or the python esptool.py.exe. There are many options available, pick the one you most prefer.
Download a suitable MQTT client to your phone (e.g., MQTT Snooper).

Attach Header Pins to the HTU-21D

Attach a 4 pin male header (included) to the board opposite the component side.
Attach 4 of a 5 conductor female-female jumper cable to the pins of both units. The colors don't matter.

position	color	net	NodeMCU
1	blue	cl	pin 26 D4(GPIO2)
2	brown	da	pin 27 D3(GPIO0)
3	white	-	pin 17 gnd
4	orange	+	pin 16 3.3v

Flash and Test the Module(s)

Install the NodeMCU lua environment

Go to NodeMCU Cloud build service and select the following 11 sub-modules: adc, enduser_setup, file, gpio, i2c, mqtt, net, node, tmr, uart, wifi. Submit the build request, and come back later when the build is complete, and download the built binary.
You may choose (why???) to download a development branch or a master branch.
Flash the module to install the NodeMCU lua environment. For example, to install the version 11 development branch floating point version.

esptool.py.exe -p COM3 write_flash -fs 32m -ff 80m --flash_mode dio 0x00000 C:\mmdefender\Install\nodemcu-dev-11-modules-2018-07-21-20-46-15-float.bin
esptool.py v2.3.1
Connecting....
Detecting chip type... ESP8266
Chip is ESP8266EX
Features: WiFi
Uploading stub...
Running stub...
Stub running...
Configuring flash size...
Flash params set to 0x024f
Compressed 458752 bytes to 297898...
Wrote 458752 bytes (297898 compressed) at 0x00000000 in 26.4 seconds (effective 139.0 kbit/s)...
Hash of data verified.
Leaving...
Hard resetting via RTS pin...

Open ESPlorer and select COM3 or whatever port the module is using. Press the module reset button. ESPlorer responds:

Formatting file system. Please wait...
NodeMCU custom build by frightanic.com
 branch: dev
 commit: fd745e0981ca2c4d425c966334cef67180f0cb63
 SSL: false
 modules: adc,enduser_setup,file,gpio,i2c,mqtt,net,node,tmr,uart,wifi
build created on 2018-07-21 20:45
powered by Lua 5.1.4 on SDK 2.2.1(6ab97e9)
lua: cannot open init.lua

Not opening init.lua is a good thing because nothing is programmed into the unit yet. Pressing the FS Info button shows:

Total : 3447234 bytes
Used  : 0 bytes
Remain: 3447234 bytes

A 3.5 mb empty file system onto which we will load the firmware.

Install the MM IOT Controller Software

Download and unzip the latest software into a folder.
For each file in the release, upload the file into the NodeMCU module.
Press the right hand "Reload" button to display the files in the module.
For each .lua file uploaded, except init.lua, right click the entry and select "Compile xxx to lc." The compiled files take less program memory, which is very scarce.
Press and release the RTS button to reset the module, and notice the additional output after the "powered by Lua" sign-on, e.g.,

39024
'tmr.stop(6)' within 5 seconds to stop running

You have 5 seconds to type "tmr.stop(6)" on the bottom command bar and hit send, otherwise the main controller program starts. You would do this to upload a modified source file and compile it for your next revision of the software.

Test the MM IOT Controller Software

Press and release RTS to restart the unit and wait for it to start. The following assumes you have connected the optional htu21d module, otherwise you will receive maximum external temperature and humidity readings:

39024
'tmr.stop(6)' within 5 seconds to stop running
> 38176
starting system
30416
30472
25176
23712
15640
15984
Wifi...
12752
8896

These declining numbers are the number of free CPU memory. If the lua OS runs out of memory, it panics and restarts. Free memory is so important, it is reported every second as "M=#" below:

Temp=-43.7C (-43.7) at 0:0 F=0 I=0 G=0 S=0 E=0 T=25C H=46.6% M=9752 (9/9:18804706) R=70~140 B=-19.0 V=3.1
state = 0 was 7 at 1 (0)
Temp=-43.7C (0) at 0:0 F=0 I=0 G=0 S=0 E=0 T=25C H=46.5% M=9584 (9/9:18804706) R=70~140 B=-19.0 V=3.1
Temp=-43.7C (0) at 0:1 F=0 I=0 G=0 S=0 E=0 T=25C H=46.5% M=8176 (9/9:18804706) R=70~140 B=-19.0 V=3.1
Temp=-43.7C (0) at 0:2 F=0 I=0 G=0 S=0 E=0 T=25C H=46.3% M=8200 (9/9:18804706) R=70~140 B=-19.0 V=3.1
Temp=-43.7C (0) at 0:3 F=0 I=0 G=0 S=0 E=0 T=25C H=46.2% M=8208 (9/9:18804706) R=70~140 B=-19.0 V=3.1

The first time, skip to #Configure the Wifi. After you set up the wifi connection, you will get

Connected to wifi as:(omitted)
9208
Starting Web Server...
Connecting to: test.mosquitto.org:1883 User: Pwd: ID:11823997
Subscribing to: /test/MMD/esp11823997Q
Ok
Temp=-43.7C (0) at 0:4 F=0 I=0 G=0 S=0 E=0 T=25C H=46.2% M=6232 (9/9:18804706) R=70~140 B=0.0 V=3.1

At some point, the OS starts garbage collection, and the free memory rises to about 11 kbytes:

Temp=-43.7C (0) at 0:5 F=0 I=0 G=0 S=0 E=0 T=25C H=46.2% M=7320 (9/9:18804706) R=70~140 B=0.0 V=3.1
Temp=-43.7C (0) at 0:6 F=0 I=0 G=0 S=0 E=0 T=25C H=46.2% M=7304 (9/9:18804706) R=70~140 B=0.0 V=3.1
Temp=-43.7C (0) at 0:12 F=0 I=0 G=0 S=0 E=0 T=25C H=46.4% M=7312 (9/9:18804706) R=70~140 B=0.0 V=3.1
Temp=-43.7C (0) at 0:13 F=0 I=0 G=0 S=0 E=0 T=25C H=46.4% M=11304 (9/9:18804706) R=70~140 B=0.0 V=3.1
Temp=-43.7C (0) at 0:14 F=0 I=0 G=0 S=0 E=0 T=25C H=46.3% M=11344 (17/16:18804706) R=70~140 B=0.0 V=3.1
Temp=-43.7C (0) at 0:17 F=0 I=0 G=0 S=0 E=0 T=25C H=46.2% M=11352 (17/17:18804706) R=70~140 B=0.0 V=3.1

and so on. 11 kb is sufficient for normal operation.

Configure the WiFi

When not connected to a wireless network, the controller creates its own access point named "SetupGadget_######" where '#' is some number.

Connect to that access point, and open in a browser any web address (e.g., google.com or http://t.c) to display a web page with a list of access points with good reception.
- Note: the controller access point and web page is on only when the controller does not have a wireless connection.

Select or enter an SSID and enter the password. The controller will try to connect and display the IP address it has received via DHCP (e.g., 192.168.1.32).

Configure the MQTT Client

Open the controller's web page with the above address followed by :8080 (e.g., 192.168.1.32:8080).
- If you can now access this web page, the controller does have a wireless connection, so its access point is not on.
Here you can control the unit's MQTT settings, and change the WiFi settings as well. You can change and save the access point, or just restore the defaults to erase it.
If it doesn't work, restart or power cycle the controller to start over.

Test the MQTT Reporting

Although the ESPlorer console displays the controller status, when deployed, the controller gets its power from the original controller +5v rail, not the USB.

Do not connect the USB to a powered on trap. The results are unpredictable, and not good. You may damage your PC or the original controller, or who knows what? You may have to remove the controller from the trap to use the USB connection.
Open mqtt-spy and create a connection to whatever MQTT server was specified on the controller web page. Subscribe to the specific topic configured. You should see your data stream match the info on the console.
You can configure mqtt-spy to save a log file, with size rotation, etc. This is very helpful to troubleshoot problems over several days worth of operation. You will need an editor (e.g., notepad++) that can open a large text file, and update the file as new data is appended.
Open your phone's MQTT client (e.g., MQTT Snooper), connect, subscribe, and observe the data stream.

When you have all of this working, you can continue to building the wiring harness, modifying the controller, and installing the Add-On.

Build the Wiring Harness

Cut a 40 or so pin 100 mil female header down to 15 pins. Sand the cut edge so you don't get injured.
Cut appropriate lengths of colored wire. The initial prototype shown here might have the wires a tad short. The Add-On should not suffer from tight wires. The prototype wires were a little too short. The signals are not critical, a little extra length will not hurt.
Solder one end of each wire to the appropriate pin on the header. Your colors may differ from these:

position	color	net	destination
16	orange	3.3v	HTU21D '+'
17	white	ground	HTU21D '-'
18	brown	LED	R2 and PIC #1
19	n/c	n/c	n/c
20	yellow	Gas	R10 and PIC #8
21	violet	switch	J1 pin 1
22	blue	FAN	via & PIC pin 7 (delicate!)
23	green	thermlo	R5
24	white	ground	J1 pin 2
25	orange	3.3v, VDD	J1 pin 3
26	yellow	sdl	HTU21D SDL
27	violet	sda	HTU21D SDA
28	n/c	n/c	n/c
29	red	Ign	PIC pin 6 (delicate!)
30	brown	LED	R2 and PIC #1

Unlike the prototype, each wire should be insulated and strain relieved.

You can use another 15 pin connector, but it is easier to use a 2 pin and 1 pin header (although you must never flip the 2 pin header).

position	color	net	destination
1	white	adc & tock1	R5 low side to thermister
2-13	n/c	n/c	n/c
14	white	ground	C6 -
15	orange	Vin +5v	C6 +

Modify the Controller PCB

To restore the original controller, these steps must be undone. Do them carefully with an eye to eventual restoration.

Make sure the tank is outside.
Cut the foil to C4 near R5 and R6
Unsolder and use a thin gauge needle or syringe to carefully pry and slightly lift PIC pin 4 from its pad on +5v, then solder a very thin (e.g., 40 gauge) 1 strand jumper between the lifted pin and the adjacent pin #5 (ground). This sets the MCLR/ signal low, which effectively disconnects the PIC (according to the spec, not tested). The alternative is to remove the PIC completely (not recommended).
Solder a jumper wire between pin 14 and the top of R5 or pin 11. This connects VDD to R5 20k0.
Locate and cut the foil on the bottom of the PCB connecting VDD to +5v to create the new net +5C, which will be fed 3.3 volts from the NodeMCU.

Attach the Harness

Carefully solder the harness wires to the strongest terminals first, then end up on the most delicate.

The right hand white and orange wires connect to the original ground and +5v rails near the electrolytic cap. It might be better if they were longer and attached to the PCB bottom to the through hole electrolytic cap, but this connection seems ok.
The single pin white wire connects the ADC input to the bottom of R5.
Strain relieve the two most delicate connections to prevent ripping up the foils.

Install Modified Controller into Trap

Make sure the propane tank is outside and off.
Disconnect the USB and connect the NodeMCU module to the headers. Connect the HTU21D.
Connect the igniter, fan, valve, solenoid, switch, and plug the trap into the power. The fan will briefly spin. After 5 seconds, the fan will turn on and the LED will start to blink.
Observe the unit using mqtt-spy. Read the thermistor temperature. It should be close to the external temperature.
Observe the unit progress the ignition start, and check that the fan, igniter, and valve solenoid all work in sequence. The unit will fail to start without propane connected. Observe the unit going into the error state (7) after several minutes.

Move Trap to Operating Location

Move the trap outside, connect the propane, observe the data stream on your phone using an MQTT client.
Observe trap startup. With the top cover off, you may have to block much of the fan using a piece of paper to reduce the air flow to get a combustible air-fuel mix.
The trap should reach 100°C and higher.

Final Test

Remove the paper, and place the cover over the trap, taking care to not crush any wires, or knock the Add-Ons. Install an empty catch basket.
If it seems Ok, go inside and let it run. Prepare a fresh attractant cartridge for your trap. Put it in.

Monitor from PC and Phone

Refine your MQTT client configuration to save log files, record only one unit, etc.
If the unit fails (internal temperature drops to under, say, 90°C), open the log file and find the time this started, then develop a theory as to why this happened, and take a corrective action, and try again. Repeat as necessary.

Post your findings on the forum. Welcome to the club!

System Requirements

(To be written.) The Defender IOT Controller Add-On ("Add-On") is intended to replace the Mosquito Magnet Defender PIC micro-controller to provide additional functionality for monitoring and troubleshooting lacking in the original controller.

The system shall support two-way remote control and status communication using an existing WiFi VLAN.
The system shall operate in the same manner as the original controller such that a user can check and operate the trap without accessing it via the WiFi.
The system shall function identically in the absence or failure of a WiFi connection or signal.
The system shall measure and report important operating characteristics such as relevant temperatures, sensor inputs, control outputs, state, faults, operating times, system resources, operating parameters, and other information of interest.
These reports shall be suitable for remote logging and automated analysis from one or more simultaneous locations.
The system shall implement an MQTT client for reporting and control.
The system shall detect and respond to fault conditions. It shall disconnect the propane source upon a detected malfunction similarly to the original controller.
The system shall respond to remote commands to restart the system, restart the combustion cycle, stop the trap operation by putting the system into a fault state, and optionally, change certain operating parameters, exercise the control outputs, and change the state for troubleshooting.
The system shall support timed operation initiated by a remove computer by accepting a special fault command to turn the trap off, and a restart command to resume operation.
The system shall include its own access point and web page for initial WiFi setup to select an infrastructure VLAN supporting WPA2 security.
The system shall include a configuration web page to set essential communication parameters, and modify or reset the WiFi connection settings.
The system shall include setup instructions on its configuration web page.
The system shall require a minimum of modification to the original controller assembly to facilitate reversion to the original controller.
The system shall obey the On-Off switch. Any fault shall be cleared by the user cycling this switch, and the trap shall restart as is done by the original controller.
The system shall drive the On-Off switch LED with the same solid or blinking codes as the original controller.
The system shall periodically attempt to reconnect to a failed VLAN or a failed MQTT or other reporting and control server.
The system shall support some level of security to block unauthorized access to the control functions.
The system shall support a future additional level of functionality that might add additional sensors and control functions.
The system shall support software updates via serial or USB connection, and optionally, by automatic live remote over the air (OTA) updates from a specified server.

System Design Description

(To be written.) The Defender IOT Controller Add-On ("Add-On") is implemented using a very inexpensive Internet of Things (IOT) NodeMCU controller module. This 30 pin device includes an Espressif Systems ESP8266 ESP-12E WiFi Module mounted on a PCB containing a power supply and a CP2102 USB to serial adapter chip.

From Wikipedia: "NodeMCU is an open source IoT platform. It includes firmware which runs on the ESP8266 Wi-Fi SoC from Espressif Systems, and hardware which is based on the ESP-12 module. The term "NodeMCU" by default refers to the firmware rather than the development kits. The firmware uses the Lua scripting language."

The NodeMCU costs about $6 and the system is open source (hopefully no tricks).

Why Lua

The NodeMCU Lua OS supports event driven functions, and programming lua is like writing Windows functions. There is no main loop. Instead, the software registers functions with event sources and are called when the event occurs. The most common source is a timer. The timer is used to send commands to and read, for example, the i2c bus. The lua code does not use delay loops to wait, it sets a timer instead. The code must not chew up the processor looping because it would interfere with other functions, such as the WiFi connections or serial ports.

Lua code can be interpreted as is or the NodeMCU can compile it. The compiled code runs faster and takes up much less precious RAM space. The system swaps compiled or interpreted code into RAM as needed. The 128 kByte RAM is mostly consumed by the system, which leaves in this case about 39024 bytes of free memory for program and data. (There is a relatively new option to support running code from the 4 mByte flash memory, which will allow vastly larger program sizes, but that has not been used in this version.)

Software Module Listing

The MM IOT Controller app consists of 8 lua source files, plus a page and some graphics for the communications settings web page:

DefMain.lc      : 4992 bytes     -- compiled version
DefMain.lua     : 8008 bytes     Controller logic
StationAp.lc    : 592 bytes      -- compiled version
StationAp.lua   : 630 bytes      Configures an access point to set up WiFi
Wifi_0.jpg      : 15456 bytes    Screen shot of the StationAp web page
arctile.jpg     : 6106 bytes     Background for the web page
conf.htm        : 3682 bytes     Configuration web page
config.lua      : 258 bytes      Current configuration settings
favicon.ico     : 9062 bytes     Icon that displays in a browser tab - this one cannot be used.
htu21d.lc       : 1992 bytes     -- compiled version
htu21d.lua      : 1701 bytes     Controls the optional temperature/humidity sensor
init.lua        : 741 bytes      "Main" module loads other modules
mosqtile256T.gif : 5009 bytes    A graphic that is tiled as a web page background
mqtt_svr.lc     : 2600 bytes     -- compiled version
mqtt_svr.lua    : 2787 bytes     Interfaces to the MQTT client
www.lc          : 3912 bytes     -- compiled version
www.lua         : 4809 bytes     Displays and handles the configuration web page
----------------------------
Total file(s)   : 17
Total size      : 72337 bytes

DefMain

DefMain.lua contains all the controller logic and pin definitions.

...

StationAp

StationAp.lua configures an access point to set up WiFi.

...

config

config.lua stores first the default then later the current configuration settings:

local module = {}
-- module.SSID = {}
-- module.SSID["NAME"] = "Password"
module.HOST = "test.mosquitto.org"
module.PORT = 1883
module.USER = ""
module.PWD = ""
module.ID = node.chipid()
module.TOPIC = "/test/MMD/esp"
return module

This file is overwritten by the configuration web page. It is read only during the initial loading.

htu21d

htu21d.lua controls the optional HTU-21D temperature/humidity sensor.

...

init

init.lua is the "main" module that loads other modules. It defines an nh() function to print free memory, a Run() function to load and initialize the other modules, then, with inline code at the end, prints the memory and a message to interrupt running.

-- file : init.lua
--for key,value in pairs(config) do print(key, value) end
--for key,value in pairs(config.SSID) do print(key, value) end
--for key,value in pairs(setup) do print(key, value) end
function nh()
 print(node.heap())
end

local function Run()
 nh()
 print("starting system")
 mmd = require("DefMain")
 nh()
 config = require("config")
 nh()
 app = require("mqtt_svr")
 nh()
 -- setup = require("setup")
 rad = require("StationAp")
 nh()
 wui = require("www")
 nh()

 mmd.start()
 nh()
 -- setup.start()
 rad.start()
 nh()
 -- wui.start()
 mHum = require("htu21d")
 mHum.init()
 nh()
end

nh()
print("'tmr.stop(6)' within 5 seconds to stop running")
tmr.stop(6)
tmr.alarm(6, 5000, tmr.ALARM_SINGLE, Run)

Setting a timer (#6 here) allows a PC connected to the serial port via usb to enter a tmr.stop(6) command to stop all further processing. This is required to update the software using the IDE.

mqtt_svr

mqtt_svr.lua interfaces to the MQTT client.

...

www

www.lua displays and handles the configuration web page

...

MM Defender IOT Controller Construction Details

Contents