Friday, 1 April 2016

Traffic Light status IoT device

Following on from an all-too-regular "Is the lasercutter working?" mail thread at our local hackerspace, I've decided to come up with a nice simple IoT 'traffic light' device.


Plan is to use KISS principles and have 3 big pushbuttons (Red, Amber, Green) that light up (and stay lit) so that the next person knows if machine needs maintenance/ misbehaving slightly / all good.


Using something like an ESP8266 module (hello Wemos D1), this could trivially publish the status to a broker, and then be acted on elsewhere - updating status on website etc

Next up, finding a local supplier of parts to start a prototype at the next Arduino-U night.

Saturday, 23 January 2016

Growatt inverter monitoring with Raspberry Pi

At home we have a small (2.5KW - 10*250w panels) PV system to try and offset our daytime electricity usage. This is connected to a 'Growatt' inverter that handily has both RS485 (wierd 2 pin plugs) and RS232 (9 pin D connector buried under a screwplate) outputs.

With the firmware on ours (installed Sept 2013) it supports modbus-rtu over serial 9600 8N1.

I had done some initial digging and experimentation (as announced on Whirlpool) but never really got sensible values out.When my guruplug (via a long USB to serial adaptor) finally died and I shelved the whole thing. With the completion of the structured wiring though I finally got round to reconnecting it and starting again.

Blue serial cable attached to structured wiring.
Small D9 Gender changer, + cisco console cable (all hail fleabay) gives a nice neat look on the outside, and in the garage I have another console cable plugged into the relevant patch outlet and a cheap usb-serial adaptor in a Raspberry Pi (which also has a GPS module connected, acting as a PPS NTP master)

Anyway, in the intervening time, someone had worked on my hacky scripts and wrapped the posting to PVoutput in an exec(curl) call -- first up I ripped that out and swapped for python requests.

I then went through the growatt modbus guide and made sure that it correctly calculated high and low byte values where these are split. The resulting script can be found on github,  and todays output can be seen on pvoutput. - a couple of charts are duplicated below.
Todays output v insolation prediction
As you can see, we had a couple of clouds going overhead today, so only generated 13KWh  vs 13.7 yesterday. Also the pvoutput fields are somewhat vague - 'Voltage' I've chosen to upload the array DC voltage rather than the grid AC volts (actually, I upload that and the grid frequency as extended data), and 'temperature' - I'd ideally like to have the panel temperatures, but upload the inverter temp so I can see if it's getting toasty. These can be seen on the 'all info' plot below

The observant of you will notice that the Etoday figure was slow to take off - this is because I didn't RTFM and discover that it's uploaded in watts, not kW...

Update 2016-02-08

If you pulled an early version of my code, please grab a new version - I realised the total lifetime generated (and any other 2*2word values) were off as I was doing thing[1]<<8+thing[2] and it should be thing[1]<<16+thing[2]. Ahem. 

The new version also just runs once in the background rather than being called from a cron entry every 5 mins, - it still publishes every 5 mins to pvoutput, but publishes all the messages (in json format) onto my message broker (MQTT) so I can draw a spiffy html5 canvas + websockets graph of whatever I fancy from 

solar/json {"Status": "Normal", "Etotal": 8705.3, "Tinverter": 46.1, "Pac1": 305.1, "ttotal": 32957749.5, "Vac1": 242.1, "PV1Curr": 1.1, "Etoday": 14.4, "Iac1": 1.3, "Pac": 305.1, "Ppv": 339.0, "Fac": 50.02, "PV1Watt": 339.0, "Vpv1": 303.8}

It also monitors the status, and if it changes to 'Fault' it'll look up the fault code and send an alert via pushover. 



Sunday, 6 September 2015

Publishing DHT22 data via MQTT with an ESP8266

Some time ago I picked up a couple of ESP-01 modules with the intention of using them as wireless temperature/humidity sensors coupled with a DHT22.

Initial investigations took place at the Perth Artifactory "Arduino-U" evenings - I managed to put on a nodemcu lua firmware and found a few (varying) dht22 libraries. however I couldn't ever manage to get it to consistently publish the information to my message broker - it'd do one or two and then lock up. I dug it out again recently and decided to have another go - especially as Pete Scargill seemed to be having success with them (running native C).

So trying to 'revert' to a newer espressif release turned out to be non-trivial - installing the relevant toolchain needs multiple bits. I gave up and noticed that there was a newer (0.9.6-dev_20150704) nodemcu release, so I gave that a try.

First discovery - There's native support for the dht sensors in the firmware, so to get the current values all you need is a
print(dht.read(4)) 
So, I trivially modified the example mqtt.client from the docs and uploaded it with luatool. I'd already set my wifi parameters by hand, so it was connecting to the network at power on automatically. Once I was happy that my 'pub.lua' was publishing OK, I added a trivial init.lua (also available on the gist)

Some points to note from that gist:

  • IP address of broker is hard coded. The nodemcu example uses a non standard port - be aware if you copy n paste
  • Although I have a last will, there's no status setting on successful connect. needs fixing.
  • I'd rather have temp / humidity as two separate topics, but I merged them into one json string to avoid having to worry about mqtt publishing concurrently (used to be fragile on the esp8266)
  • I publish every 5s (tmr.alarm) - 2s is the min recommended for the dht22
so I now see a pretty
sensors/ESP-10264640/json { "temp": 16.8, "humidity": 53.4 }
every 5 s ("mosquitto_sub -h broker -t '#' -v" makes for great sanity checking), which is great but not terribly pretty. Thankfully I have a websocket enabled mosquitto broker running, so I'd already dabbled at some html display. so I took jpmens' dial example and altered it to one of the other gauge styles. and lo...

Sunday, 14 June 2015

Satellite Tracking / New rotor controller

(it appears I'm about due for my annual blog post entry). Those of you who follow me on twitter will be aware that I've just acquired an old Kenpro 5400 (this is roughly the same as the Yaesu G5500) Azimuth / Elevation rotator, that I plan to use to track cubesats and play with for ham radio.

On opening the control unit (I wanted to see if there were any other primary taps on the transformer, as it's a 110v controller) it was evident it had been 'altered' in the past. To quote someone on #highaltitude "that wiring job is responsible for a thousand dead kittens",

hence a plan was developed to leave the existing controller as an emergency spare and build a fresh 1U rack version instead. The ideas (such as they are) are on a github gist that I'll keep updated with plans. The rough idea being to have a decent embedded board (probably a beaglebone black as a Raspberry Pi depends on an SD card) controlling the relays for output directly, and reading in the potentiometer values to calc position. Using a more powerful microprocessor than say a pic or atmega (arduino) means I can update TLE's automatically and offload much of the tracking directly to the controller - meaning any SDR receivers can concentrate on the signal alone.

I'm also going to house in a GPS module (most likely another one from upu) so that it doubles as a stratum 1 NTP server as well as having accurate position to calculate passes from.




Thursday, 10 July 2014

Fedora Catchup

The couple of packages I maintain in Fedora have been sitting stable for so long that I've not really had much to do with Fedora recently (that, and getting a mac laptop for $work), but I've just discovered https://badges.fedoraproject.org/ so it's now time to claim a few extras (oh, and push an update to PyEphem while I'm at it...)

Friday, 6 June 2014

Happy Cheeks vs SuSE Chameleon

Happy Cheeks imprisoned in a Cray

Kids today. Joyriders in the supercompute cell
Friday Afternoon, and Operations staff are summoned to the Pawsey Centre as the evil SuSE chameleon has been chasing Happy Cheeks (the iVEC Quokka) around the supercomputing cell.

Happy Cheeks and Chameleon explore 'Magnus' 
Happy Cheeks and Chameleon on Galaxy
Inspecting the layout for the Petascale expansion

Being Chased



Monday, 19 May 2014

Pretty Colours via MQTT

What does a geek do when they have some spare RGB LED strip (addressable WS2812B) and some cheap nasty LED devices? LED transplant time...

So, first to go was the LED glass prism stand received as a christmas present - out went the potted pcb with three fading LEDs, and in went a single piece of RGB strip fixed in place with a hot glue gun.
wire comes out the bottom and goes to a nanode.
So far so good, but I don't just want fixed or fading colours so time to revisit an IoT idea: Cheerlights

The cheerlights API defines 10 colors that can be set, but I want the possibility of sending any RGB value, so I created @FakeCheerlights as an MQTT series of topics on the test.mosquitto.org broker

fakecheerlights/rgb
fakecheerlights/colour
fakecheerlights/raw

which contain the hex RGB value, the identified colour name and the raw tweet.

A separate script (running on the NAS) uses the twitter API via tweepy to follow the twitter stream search for 'cheerlights' and 'fakecheerlights' mentioned in a tweet. If a colour name (matched from the X11 rgb.txt) is found then it publishes the corresponding hex value to the broker

Since fakecheerlights uses a publish/subscribe model, it's *much* faster to react than the original cheerlights protocol which relies on a client polling the server API. The downside is there's no nice fade time between colours.

The nanode (I have one of the earlier batches) was designed as a low-cost ethernet enabled arduino, so uses the Microchip ENC28J60 ethernet rather than the wiznet of the arduino shield. Thanks to UIPEthernet.h and PubSubClient.h it's just possible to code in a basic subscriber which sets the strip output to match.

Since I plan to use the pub/sub model at work for monitoring the machine status and batch queues, I gutted an old ikea childs lamp and replaced the LED with another WS2812B and hooked that up to a freetronics etherten with a PoE daughterboard attached. Sadly the hardware revision I had didn't include the MCP 24AA025E48 that my old nanode did, so my sketch had to include a hard-coded MAC address.

A short youtube video demonstrates the reaction time, and all the source code is on github. (with the exception of the nanode sketch as I didn't save it before closing the arduino ide)