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HTTP vs MQTT

Mosaic

Well-Known Member
Thread starter #1
Hi All :
I did an app and prototype based on the ESP12E IoT chips.
I am getting irregular comm issues....sometimes it's 100% sometimes down to 50%. No WiFi competition the router signal is 5 ' away.
The app was done in HTTP/TCP via the arduino IDE. I see that MQTT may be the better approach.
Can anyone advise?

EDIT: I also discovered the ESP8266 I2C protocol init string is flawed in the arduino IDE. I am forced to read the first I2C byte twice and discard the 1st read as it returns a NAK instead of an ACK when the logic analyzer looks at it.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
#2
I'm currently playing with ESP's writing to a MYSQL server on one of my websites, the ESP's wake up every ten minutes or so, read the temperature, humidity, and battery voltage, and upload it to a remote server via a PHP script - it also uploads the WiFi network it's connected to, and the signal strength.

So far they seem to be working flawlessly, here's a link to the graphs of the two currently running:

http://www.lpilsley.co.uk/php/espgraph.html

The top graph is an ESP01, actually connected to USB on the PC I'm using at the moment - and as it's an ESP01 the battery voltage is actually the internal supply in the chip. The lower graph, which I built today is a Wemos Mini, running off a Lithium AA cell, connected via a USB charger/protection board (and monitors the actual battery voltage) - the unit is currently sat under the eves of my house - the initial high temperature and low humidity was when it was at in the sun through my attic window. I haven't actually measured the current consumption, I'm just waiting to see how long the battery lasts.

My main problem at the moment is the graphing, I wish to have the X axis labelled in date and time, but I'm struggling getting PHPGRAPHLIB to do it - altering the x-axis interval removes the labels entirely.

I've also got a third ESP running, another Wemos Mini, with a battery charger shield fitted, and that's running from an 18650 battery - as the shield up-converts the battery to 5V, it's presumably taking more current than the bare Wemos version?. This one simply uploads to a CSV text file via PHP on the same server - it's been running since 23rd April, and the battery reading is currently 3.98V. The CSV files is now over 90Kb.
 

Cicero

Active Member
#3
I've done quite a bit with the ESP's and MQTT. For the cost, and the level of community uptake and support for them, they're great.

I never use them with standard AT cmd firmware though.

MQTT is meant for distributed, low bandwidth, and potentially low reliability networks. Like a distributed network of sensor nodes located around the world, all connected to the internet. If you're simply talking over a local router, then there should be nothing wrong with raw TCP/UDP or even HTTP, they're solid. You can use MQTT for local use not utilising the internet, you just will need a local broker, but that's easily done with a RasberryPi or similar.
 

Cicero

Active Member
#5
When u say a local broker....this is not a router?
No, but you can think of it like a router if you like, but specifically for MQTT messages.

Its a different piece of equipment/program connected to the network via the router, but specifically running as an MQTT broker. It will ferry (broker) all subscribe/publish messages to the relevant devices.
 
Last edited:

ronsimpson

Well-Known Member
Most Helpful Member
#8
absolutely need a broker
What I did before; each node had its own web page, or each node used a network serial port, or could email out, or ....
So I was planning on using a Pi-0 on each node. But the MQTT looks tempting. I do have a Pi-3 in the middle of all this.

I am a hardware person and having complexity problems. lol Gave up on getting the Pi-3 to be a server. Decided to update and bricked the Pi last night. Had to start over from zero. Back up and running.

I am trying to replace my 25 year old home control computer but can't get a Pi server running and my python-ability is very low. And my head is slower than 25 years ago.
 

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