Category Archives: ESP-07

Christmas at Bedrock

Well it certainly feels like Christmas here at Bedrock (while I’m here, check out this unrelated item – the Ameba – looks interesting).

I got up this morning to a large bag of post – including a new battery for Maureen’s Samsung laptop (though why I mention that in the context of Christmas I don’t know as it is me that has to put it together!!). It’s our 31st anniversary today, incidentally!!

Anyway, there was a parcel for me from Bob Elmour.  He’s been working with ESP8266 boards and like Aidan and myself, making his own boards up. We had a chat a while ago and he said he would send me some samples to play with and write-up.

WELL, I’m very excited – so this morning the package turned up and inside were these VERY professionally packaged and assembled boards as well as some spare parts etc. They are called IoTBear and you’ll be seeing them on EBay and elsewhere soon. I urge you to take a closer look.


These (at least this version) are brand spanking new. There are two boards here – firstly the little IoTBear board with in this case an ESP-12F board – but as you can see they’ll handle everything from ESP-07 upwards.

Essentially the boards have little more than an ESP-12 with a regulator, a reset/programming circuit (on one button, short press to reset, long press to program),, a connector for an FTDI at the end (exactly the same as we would do – why waste putting a USB chip on the board) – and all the pins brought out at convenience 0.1” centres. On the underside, the relevant pin names are printed and there is a cut-able link to disable the one-button programming.

undersideThe other board is similar but with a micro-USB connector for power – and a nice prototyping area – AND though not using the USB pins other than power, he’s brought them out onto 0.1” holes – now THAT’s handy for experimenting.

So this is not a slick commercial operation, just a private individual as far as I’m aware who like use started doing this stuff for fun – his website is not up yet but I’m putting it here for future reference. You will find Rob on EBay as user Majikthi5e and if you are interested in any of this stuff I suggest you contact him from there. I’ll not put his email address in here but he’s welcome to share it if he wants in the comments. It is my understanding that he plans make everything from bare boards upwards available. There is some stuff on EBay already.

with FTDII’ve a fair experience of the ESPs and issues with boards and the 3v3 regulator he has used is a good one and the SMT parts are a reasonable size for hand-soldering (with a fine bit – none of yer gas soldering irons please). The only thing that would worry me assembling myself is that micro-USB adaptor but then my eyes are getting old.

The prototyping are is GREAT for all sorts – sticking displays on, relays – all sorts. From what I gather the cost will be reasonable so you could have a bunch of these lying around.

As you might imagine, the very first thing I did was to get out the soldering iron, solder up the 6-way connectors for FTDI programming and program up the boards. I held the little button down and flashed my software into them – no problem first time. I’m looking forward to doing some prototyping with the larger one in the coming days.

OH and there’s a nice 4-sided documentation comes with these board, simple and well presented.

My only gripe so far is that the board is relying on DTR and RTS for programming without pressing a button. TWO issues with that. DTR is fastened straight to GPIO0 – and that leaves me to wonder, what if someone is using GPIO0 as an output – conflicts?  Also – it is assuming two things – that you have control over RTS – and that RTS is available on your FTDI – and that leads to two things – firstly RTS is NOT available on all FTDIs and indeed many – on that matching 6 way connector, bring out CTS – which is an input – not an output. Indeed ALL the FTDIs that I’m aware out have CTS next to the ground pin.  For these reasons – I think I’ll be experimenting with these boards using the programming button and GND/VCC/TX and TX only connected to the board.

Anyway, over to you – if you’re interested get in touch with Rob.


Blowing the Home Control 2016 Code

Hackitt and BodgittThis is for the people who’ve been trying out my software (or thinking of trying it out) on the ridiculously cheap (£1.40) but very reliable, powerful and comprehensive ESP12 WIFI processor board and those who’ve gone ahead and gotten some boards we made – all referenced in earlier blogs. For the latest on how to FLASH the chips see this blog update.

Essentially the assumption here is that you have an ESP-12F-based )(or variation such as ESP-12E) board of some description and that GPIO0 is used as a programming button (held to ground to program etc) – and also as a web setup button.

Let me explain the difference between programming and setup. GPIO0 is set up permanently by Espressif as the pin to hold LOW before and during power-up to put the board into programming mode to replace the firmware (which may or may not exist on purchase… could be that AT-Command firmware, LUA or something else). Web setup is just something my software does – it’s not the only software to do so. It may use GPIO2 or GPIO0 AFTER power-up to put the unit into a mode where it acts as an access point, allowing setup for, for example SSID and password.

All other I/O pins are available for one use or another including GPIO16 – take note of other blogs describing wiring and power unless you’re using something like a node-mcu board which just plugs into USB. The software works with my Node-Red software – again described in the home control blog – what’s new here is that OTA now works and you don’t need a development environment to program up the code which  I developed with lots of help from others, using the unofficial Development Kit in Windows. The software will react to MQTT commands and also commands coming into the serial line at 115k baud (serial commands are the same as MQTT payloads - no topic required). - home controlI worked with Richard Burton to get RBOOT working on our code– it is his software which allows for OTA (remote updating) when developing, in my case, in C on the ESP8266.

With OTA working (including from an external location) I thought I might try taking the ROMS and blowing a chip from them rather than from the editing system – that way others can benefit.


Well, I went to get the NODEMCU flasher which was always good – so after a couple of blind alleys – I got to this link..

As you can see, with the flasher, the RBOOT rom loads at 0x00000 and our current code runs at 0x02000. Unlike me, make sure BOTH ROMs are ticked on the left.. as the first one is so short it shows little or no sign of activity. I found I could flash at 46800 baud, you may or may not wish to play safe at 115k baud.  You may also note there is an additional file needed above – in SDK 2.0 and above, on first installation this is needed. See THIS blog entry for up to date information.

So – you blow the software onto the ESP8266 board (here is the link to the NodeMCU – no guarantees as it isn’t mine), now what?

A reminder – what will my software do?

  • Turn outputs on and off with optional timeouts
  • Read inputs
  • Handle RGB Serial LEDs (up to 300 of them assuming you have enough 5v power)
  • Handle PWM 12v LEDs (assuming you have a 12v source and driver hardware such as Mosfets)
  • Act as a LED clock (and a nice one too) with 60 serial LEDs.
  • a TON of other things including handling DS18B20, DHT11, DHT22, talking to Nextion displays (see the Serial Nextion blog) and WAY more – all in the Home Control blog. Add to that the power of Node-Red and you have the basis for a very good and reliable complete home control system.

But first the unit needs to be setup. After programming and then resetting or power-cycling the ESP12 (suggest hooking a LED and resistor to GPIO13 and down to ground) – the light will start flashing – within a second or so – hold GPIO0 (or GPIO2 depending on defaults in the current ROMS – see power-up messages coming out of the serial at 115k baud)  to ground for say 10 seconds and let go (DON’T press for the first 100ms of turning on – JUST after turning on or resetting will do – if you come in early (and if the current pin in use is GPIO0)  it will go into programming mode – of course if you don’t program it, no harm done – just reset and try again).

NOW you can access the board with your mobile phone WIFI as “hack-Setup” and once connected use the phone browser to go to and you get that nice setup on the right above which needs at least one router SSID and password, two if you have them available (second is a backup) – the address of an MQTT broker and username and password and that’s really all that is essential to start off.

Once everything is up and running , the LED on GPIO13 should be flashing very briefly (i.e. off most of the time) – a variation you can setup by commands uses an RGB LED to give more meaningful use (yellow power up, green working, orange working on it, red dead – throw in the bin etc).

You can now talk to the board via MQTT… or the serial port at 11500 baud (you could use my serial terminal.

If using the serial, fire {debug} at it – if using MQTT – then assuming you’ve given it the name “fred” then the same command would be – topic:  fred/toesp and the payload would be {out4;1} or {out4:0} to flick GPIO4 on or off (or if your board is mis-labelled as some are – GPIO5).   The Home Control blog entry goes into the rest of this in detail.

Note that if you DON’T set up an MQTT broker, the unit will try to connect to MQTT and eventually reset and start again. This is deliberate. You MUST setup an SSID, an MQTT broker and once running you should use the ESPLOGIN mode or similar to send the time to the unit shortly after power up then every 12 hours or so. Again this is detailed in the home control blog… it’s quite simple.

The rest is up to you.  I use this with my Node-Red software and I have a node for setting up the time and date on the boards…  it is called node-red-contrib-esplogin

Node-Red controls - Peter Scargill

That log-in node incidentally is available here.

That’s it for now… I’m quite chuffed the OTA now works. This of course is directly relevant to the Nextion WIFI Display project.

You can get the three BIN files from:

IMPORTANT NOTE: If you choose to use ROMS rather than compiling code, you will need to keep up with the BITBUCKET repository changes as these ROMS will be updated when I make changes – which I’ve just done having realised I need to support some older boards we made with a relay on GPIO0 whereas I’m now considering GPIO0 should be an input. There is also a DOC file in the Home Control blog and that is the ONLY up to date guide to the ever increasing instruction set.

Update 14/05/2016:  No longer showing passwords in the web setup page so you must put those in every time you use the setup page – otherwise you end up with blank passwords – which you might want. Added several new commands like cpu_clock so you can double the clock speed  - documented… ROM updated. DEFAULT pin for web updating is generally GPIO2 but on power up you’ll see serial messages which TELL you which pin to use. You can change this to GPIO14.

Update 24/07/2016:  See the changes in blog above, rendering some of the comments below obsolete.



EMW3265Erm, no, though you might think so by this headline..

Read the comments – the $5 ESP8266 – where?  $2 ESP8266 more like it – less, even -

There’s even a claim that this new single-source board (Seeed Studio) has MORE memory – well at least one variation of ESP12 has 4Mbytes – and the EMW… according to the ad, 512K.

And what about the all important Windows and Linux support libraries? Erm, no.

Another comment – Chinese documentation? Well I don’t know about you guys but I have  raft of English documentation that until recently came with the Espressif SDK and which is now maintained online.

And the last – Chinese – guess where SEEED are!

Cheap, reliable, effective, more compatible variations of ESP and more suppliers than you can shake a stick at – and we want to move for what reason?

But – if you like spending money – there’s this – even more expensive -


Automatic Router Selection for ESP8266

I wonder if anyone who has done this can help.  As most of you know, I program my ESP8266 devices in C.  I've been having some issues with weak signal recently and it would be really nice to have a list of acceptable access points and their passwords - and have the ESP, if it loses the signal, check the list (including identical SSIDs) and reconnect.

Has anyone done this already and if so would they care to share code?


ESP8266 Remote Access

Notice I titled that remote access as against remote programming – but that’s part of it.

Years ago, having gotten sick and tired of dismantling my home control Arduinos just to upgrade the code, I purchased a couple of small units from China which I’ve just thrown in the bin.   One had a USB plug on it and plugged into the PC, the other had an FTDI output on it. Both had those black 2.4Ghz antenna.

So the purpose of these units was to wirelessly replace an FTDI – or serial programmer, the idea being that instead of bringing the Arduino project back to wherever one programs the devices, you plugged the unit into the project and over the air programmed it.

At the time I was using Arduinos and those CHEAP £1.50 radio modules – the NRF24L01s, the worst radio boards in the world who’s range could be so bad you’d be lucky to get through one wall. I had high hopes for them with a great mesh network called RADIOHEAD, but ultimately their range and lack of ability to read signal strength doomed them.   However, as you can imagine they were dotted all over the house and I thought this little radio pair would solve the issue of programming them without ripping everything up.

It turns out the “radio FTDI” had the same problem – it was based on the NRF24L01.

Fast forward to September 2015. Here I am in Spain with a new setup of ESP-12 modules controlling lights, watering system and a lot more.  I’ve made some improvements to our “home control 2015” software in the ESPs and once again I find myself having to dismantle kit.

Now, I know that is it possible to program over the air – a few guys have tackled this successfully and indeed much of the code is built into the Espressif SDK. Right now my friend Aidan is working on adding this to our code but there are two issues, he’s not had luck up to now and secondly as our code comes to something like 300k you’re never going to be able to add this to the ESP-01 modules (we use ESP-01 sometimes, ESP-12 other times…)  as you need as much spare storage as you have code for OTA programming!

It was with that in mind that last night I dragged out the old FTDI boards to see if I could save myself the effort of dismantling the Pergola lighting system to update it.  Suffice it to say that I managed to get a few bytes programmed before that all came to an end despite several attempts. With around 25 WIFI units of one description or another dotted around the place, the old wireless FDTI (same frequency range) simply could not handle more than a few feet.


I figured it would not hurt to look around and see if someone has alternative wireless solutions – lots of time has passed since I bought that kit.

And so it was that I stumbled upon this. – as it happens it is quite new – essentially what we are looking at is a single unit (yes, that had me going for a while) which will hook into the WIFI system and act like an FTDI – given that you can fire the serial out of your PC over TCP to a port – port 23.   I grabbed the code (the stable 1.04 version) and very excitedly blew it into an ESP-01 unit I had lying around.

Really, nicely done web interface (with remnants of Martin Hanzarov’s code in there) and a really good write-up – indeed there may be enough info in there to help us implement our own FOTO (over the air) updates to our code.

But this has far wider implications – a virtual serial link would also let you monitor the serial line of a remote unit for debugging info – and our units do indeed put out lots of serial debugging info. It would also let you remote program and monitor un-wirelessly enabled Arduino projects.

So the first problem was – I had this unit sitting as on my network and I needed to blast info into port 23 to have it come out as 115K serial.  I have ECLIPSE sitting on the PC running my projects and there’s a line in the MAKE file that says “COM6”.  I have absolutely NO idea how to turn that into a TCP statement if indeed it can be done (FEEL FREE TO START TYPING IF YOU KNOW HOW).

So I turned to a 30 day trial of a PC program that promised to provide a “virtual com port” – and that it did. Serial/IP Redirector let me create a link to port 23 and ship raw data back and forth to COM22 (which doesn’t exist on my PC)- LO AND BEHOLD I set it running, put PUTTY on the PC talking to COM22 and with a real FTDI attached to the little ESP-01 board on real COM6 I set that running on a terminal –at 115K. Utterly flawless raw serial communications – rock solid.

I was getting excited by now. I took my ESP-01 board and cross-connected the serial to an ESP-12 test board. I held GPIO0 to ground and turned the power on, putting the ESP12 into programming mode.

I punched COM22 into the ECLIPSE project and hit the FLASH button on the project. Lights flashed on both units. With a scope attached  to the serial in on the ESP-12 I could see clean 115k data going into my project and… nowt, zilch, nothing.

I was up until the early hours ensuring the baud rate was ok and that my level conversion wasn’t getting in the way – you see all my projects use a resistive divider on the serial input of ESP boards so the whole lot will work just fine with 5v logic on the FTDI and elsewhere.  I wondered if hooking two of these units together with serial cross connected might prove too much but the scope says no – it says I’ve a perfectly reasonable serial signal going into the ESP-12 – but it’s not having it – no responding output whatsoever. Eclipse tries sending out data over and over and eventually gives up just as if there’s nothing connected.

So near and yet so far.

I got up this morning and the unit was still rock-solidly connected to the WIFI and typing a few characters provided perfect results at the other end – but I cannot program ESP units – yet.

Very exciting, yet very frustrating.

Perhaps coffee and a new start to the day will help. BUT I had to bring this to you as the article is really good, the software seems to WORK and there’s a super-bumper version with it’s own OTA updating in the works for larger targets like an ESP-12 (more FLASH) than the ESP-01.

I’m sure this is going to be a winner – just need to get it to work. After all, the ability to add remote programming to any FTDI-enabled project for what, a couple of quid.. well, you just can’t ignore it.

Meanwhile if anyone reading this firstly knows how to set COMX on Eclipse (on Windows) to TCP – do let me know – and if you really think you know what I’m doing wrong here and want to jump in before I figure it out – by all means – you have the keyboard…


QD Tech Displays on the ESP8266

QDTECHI’ve seen a number of projects using an Arduino and an ESP8266 to drive LCD displays. You may know that my home control has used a 1284-based board (MEGA type) to run a nice Thermostat display for some time now. The displays look very pretty in the right box.

THIS article will tell you about the display but you’ve seen them on Ebay no doubt.

Banggood do the displays (I can’t help thinking the price has gone up – at £3 inc postage – but still cheap)

Anyway, they are 160*120 and very bright and colourful displays, excellent for simple stuff.

displayI’ve always wanted one of these to run on the ESP-12… on the Arduino assuming 5v you need series resistors for the outputs – as it’s a 3v3 device internally, but with an ESP you can run them directly. So, the device and it’s backlight go straight to 5v, the 4 inputs go straight to ESP8266 pins and the reset can go to the ESP8266 reset pin – again directly.

That’s the easy part – the software not so – there are not a lot of drivers out there for this board for the Arduino – one that does work offers a choice of hardware or software SPI and that’s where the magic comes in – if you eliminate the hardware SPI code it all starts to look quite easy. So yesterday I set about (with no anticipation of success) converting the code firstly from nicely object-oriented Arduino code – to basic C – and secondly to use ESP8266 port pins. I cheated slightly by using EASYGPIO to make the port operations a little more obvious but I don’t think that has cost too much in speed.

Anyway to cut a long story short at THIS point I’m off to the coast for a couple of days sunbathing and I’ll leave you with my work in progress. I’ve NOT added in the code to handle characters/fonts yet but I HAVE got this working completely reliably – drawing boxes and lines.  Right now there is some setup data in RAM, I’ll move that to FLASH shortly (you need a function to access 8-bit FLASH arrays to stop the ESP crashing so I left that until last). Why bother with FLASH? Well, you’ll definitely need to put fonts in FLASH as they get big, quickly.

I’m assuming you’re programming in C – don’t ask me about getting this running in Arduino code or Lua.

Here’s the header

Here’s the C code

I’ll assume you already have a project running and just want to add this to it. I’ve reduced includes to a minimum..

My test includes a red screen background, a green box and a blue diagonal line. So with the includes this is all I put in my code (I slightly altered the init code to include ports (not including RST line as you fasten that to the ESP reset – hence needing only 4 port bits – you’re not stuck with my choice – the last two parameters are the screen size).

for (int qq=0; qq<160;qq++) QD_drawPixel(qq,qq,QD_Color565(0,0,255));

There it is – a starter only.. but it works – if this were taken to an extreme it would include character handling and hardware SPI – I’m guessing compared to Arduino use it would be pretty FAST..

Now if anyone wants to take this on and add the bells and whistles..

Oh and how would you run the data in FLASH? not so hard… here’s a typical FLASH-based array snippet.

static const uint8_t ICACHE_RODATA_ATTR  kelvin[] = {
        255,  51,   0, //    1000
        255, 109,   0, //    1500
        255, 137,  18, //    2000

And to access that…

// This routine courtesy Richard A Burton - way better than using 32 bit flash arrays (you can't directly
// access 8 bit FLASH arrays directly - will crash the processor)
uint8 ICACHE_FLASH_ATTR read_rom_uint8(const uint8* addr){
    uint32 bytes;
    bytes = *(uint32*)((uint32)addr & ~3);
    return ((uint8*)&bytes)[(uint32)addr & 3];

Typical use;;;


So you can see it won’t be TOO hard to get a load of font data into FLASH – sure, it’ll slow things down a little accessing it – but how that actually affects operation is something we’ll discover in the future.



I recently put out a question about the RAM in the ESP8266. In a typical compile, for me I might see…

Idx Name Size VMA LMA File off Algn
0 .data 00000894 3ffe8000 3ffe8000 000000e0 2**4
1 .rodata 0000275c 3ffe88a0 3ffe88a0 00000980 2**4
3 .bss 00009a80 3ffeb008 3ffeb008 000030e8 2**4
4 .text 00007786 40100000 40100000 000030e8 2**2
5 .irom0.text 0003ce04 40202010 40202010 0000a870 2**4

All very confusing.  So .irom0.text is FLASH – why they can’t just call it FLASH I’ll never understand. The rest are various kinds of RAM.

.data is used for “initialised” data, i.e. that which needs copying from FLASH on powerup. I’ve used 0x894 in the above example.

.rodata is used read only data – this is in ram (again I don’t understand, if it is read only why it’s not in flash – most likely for speed). I’ve used 0x275c.

.bss is used for variables which are not initiased. I’ve used 0x9a80.

.text is used for CODE that is not in FLASH – i.e. it is in FLASH on powerup – but gets copied to RAM for speed.  Sadly due to lack of RAM we usually end up using a directive to put code into FLASH to save space – but REALLY time critical code should be left in RAM. Of course it does get copied into RAM (cacheing) but that could mean execution times which are different first time around – not good for RGB LED lighting etc.

A fellow by the name of Don Kinzer replied and here’s what he had to say.. very useful.

“There are no individual limits for the sizes of .data, .rodata and .bss (but see caveat below). The ESP8266 has 80K of User Ram which is occupied by .data, .rodata, .bss, the stack and the heap. Basically, the space represented by (80K - sizeof(.data) - sizeof(.rodata) - sizeof(.bss)) is used by the heap growing from one end and the stack growing from the other end. If the heap and stack collide bad things will happen (probably an exception, eventually, and a reboot).

The caveat that I mentioned is that the .data and .rodata sections, along with the .text section (itself limited to 32K) must fit in the first 64K of Flash. The sizes of each of these sections is rounded up to an integral multiple of 4 bytes and an additional 8 bytes of overhead are added for each section plus an additional 8 bytes of overhead. Finally, space for the checksum is added (between 1 and 16 bytes) so that the overall size is an integral multiple of 16 bytes. The total of all that must be 64K or less. The image containing all of this data is often called app.v6.flash.bin but the name itself is not important.

As for the limit on the size of .irom0.text, that depends on 1) the size of your Flash chip (commonly 512K but can be 16MB or more), and 2) where you load it into Flash and 3) if you want OTA upgrade or not. For non-OTA upgrade, it is common to load the .irom0.text at 0x40000 but it can be loaded as low as 0x10000. Since the system parameter area exists at 16K from the end of the Flash chip, the size of .irom0.text is limited to sizeof(Flash) - 16K - loadAddress.

If you want to load the (non-OTA) .irom0.text at an address other than 0x40000 you'll need to modify the linker script accordingly.”


BASIC for ESP8266

Don’t get me wrong, we don’t yet have a fully working interpreter, but a link appeared on my ESP8266WIFI Facebook page thanks to Michael Molinari this morning and I thought I’d give it a whirl.

I grabbed the Windows loader (Windows 10 put up a SEVERE warning about this which I totally ignored), plugged an ESP-01 into my FTDI and blew in the interpreter, all of which took a couple of minutes and zero effort.

At first I didn’t know what to expect, I looked at the serial port – nothing.. then realised it outputs at 9600 baud, not my usual 115K…. I then started typing stuff into the serial – nothing – at which point I noted it already knew about my router – I can only assume that is because the WIFI passwords were already in the board, normally you’d have to use the board as an access point just to put in your WIFI details… anyway, I managed to bypass that.

I checked the examples on the page – hello world and a graphics example – which worked right out of the box!! Imagine that – simple BASIC commands putting out graphics on a web browser from a twopenny WIFI board all on it’s own!!

At this point, things went down a little. I tried editing the code (in the web browser!!) and it wasn’t having a SAVE – I noted on the serial that it had crashed… but then if you look at the dates this is all very new.

Seriously this has to be worth a few minutes of your time – assuming the project continues and these niggles go away, you just don’t get a quicker, simpler and cheaper way to get a web page with buttons into an embedded device – even if just to do some simple stuff. This is now ENTIRELY down to how much effort the author puts into this.

Go take a look! These images should enlarge on click/touch. Well impressed IF development comes quickly enough….

Basic Interpreter for ESP8266   Graphics on the ESP8266


RGB versus HSV

Image author SharkDIn implementing my own home control solution which you’ll find in this blog “home control 2015” the software has been and remains a work in progress – mainly because I keep finding bugs and adding new features.  I’m fairly confident that most of the bugs that have plagued me over the months are gone. For example NONE of my boards has failed in the last week – running constantly, turning things on and off, monitoring temperature and humidity, powering RGB LEDS…

And that brings me onto tonight’s subject.  You may have  noticed elsewhere that I’m getting fanatical about the Nextion displays because now at last I have the potential of a nice touch display for the wall to control things. You’ll also notice I’m realising their code is VERY early – but that’s another subject.

The first addition I made today to the home control system was to allow any of the ESP boards to send an MQTT message to any other board. Of course that is built into the MQTT library in the first place and there would not be a lot of use in having the Raspberry Pi brains send a message to one board to send a message to another.. but it occurred to me that an essential feature of a serial wall mounted display would be to control more than just the ESP8266 board that it is actually attached to!

So – in went a new command to send out an MQTT command from the serial input on the board so that the ESP board could pass the message on. That’s a little tougher than it sounds as I only had one string argument available in my line parser so I had to delve into that – however, it is now all done.

And that led me to thinking about how my wife Maureen would control the coloured lighting around the house, from the wall.

RGBObvious really, RGB sliders – you can make any colour or hue from RGB can’t you – any techy will tell you that for free.  Sadly the rest of the world does NOT know how to manipulate RGB. Any paper artist will tell you that the primary colours are red, yellow and blue! Not in my world they are not.

And so we have a problem – how to better enable any old user to play with colours – and hence I started reading and it is pretty clear that a better model is HSV, or hue, saturation and value - brilliance in other words – I looked up HSV on Google but the best I could find was Herpes Simples Virus. I’m going to continue to refer to brilliance as the word “value” means nothing to me in this context.  The problem with RGB is – let’s say you get a really nice pink. That’s fine at full brilliance but how would you keep that shade of pink as you turn down the brilliance… even for a techy that is not easy faced with 3 sliders.   With HSV it’s a snap.

And so I’ve been looking at code – I found some great Javascript code and in fact I now have that running on my little WEBSOCKETS project – but what about C to put into the home control project… I found this after much searching.  Excellent code and simple to implement – do I put that into the ESP C compiler? NOPE – it needed a couple of includes that screwed everything else up because of the FLOOR function… so then I found this…

int inline fasterfloor( const float x ) { return x < 0 ? (int) x == x ? (int) x : (int) x -1 : (int) x; }

That solved the floor function and I was up and running.   H values 0-359, saturation 0-255 and brilliance 0-255.

Thinking about a display, a simple colour wheel with touch points along the way, then 2 sliders… that’s it - full intuitive colour touch control.

Well, it was enlightening for me – I hope you found this useful.


Driving me NUTS

This has been driving me mad and I’ve only just found the answer – thanks to some clues people have given me – but as many of the responses were wrong – you might well find this interesting.

I have a an array of 180 bytes – for 60 serial LEDs – 3 bytes each for red, green and blue respectively.

So this routine calls back every second – and updates the 60 LEDs which are in a circle. The hour indicator is formed of 7 LEDs, bright in the centre, dimmer to the edges, the minutes indicator is 3 LEDs – again bright in the middle. The seconds are shown as 1 LED.

And it was working a treat – except at midnight where it bombed with all LEDs on – and for the LIFE of me I could not see why..

Ignore the bits in RED….

LOCAL void ICACHE_FLASH_ATTR clock_cb(void *arg)
if (sysCfg.clock!=255) // fancy clock on a port
        wsBitMask = (uint8_t) sysCfg.clock;

        int hour12=(tm.Hour%12)*5;
        for (int a=0;a<180;a+=3)
        rgb.buffer[(tm.Second*3+2)%180]=255; // seconds hand blue

        rgb.buffer[(tm.Minute*3-3)%180]=8; // minutes green
        rgb.buffer[(tm.Minute*3)%180]=255; // minutes green
        rgb.buffer[(tm.Minute*3+3)%180]=8; // minutes green

        int x=((hour12)+(tm.Minute/12))*3;


        WS2812OutBuffer(rgb.buffer, 180,1); // 60 LEDs

So here’s the thing – all these years I’ve been thinking % was a MOD operator – it’s NOT – it’s a simple remainder..

In order words..

(-3 % 180) which I had COMPLETELY expected to be returning 177 – was in fact returning –3  !!!!!

That explains a LOT. The solution – a simple MOD function.

LOCAL int ICACHE_FLASH_ATTR mod(int a, int b)
   int ret = a % b;
   if(ret < 0)
   return ret;

Hence mod(-3,180) returns the right answer. Here’s the final clock once-a-second callback routine for a 60-LED array.

LOCAL void ICACHE_FLASH_ATTR clock_cb(void *arg)
if (sysCfg.clock!=255) // fancy clock on a port
        wsBitMask = (uint8_t) sysCfg.clock;
        int hour12=(tm.Hour%12)*5;

        int a;
        for (a=0;a<178;a+=3)

        rgb.buffer[mod(tm.Second*3+2,180)]=255; // seconds hand blue
        rgb.buffer[mod(tm.Minute*3-3,180)]=8; // minutes green
        rgb.buffer[mod(tm.Minute*3,180)]=255; // minutes green
        rgb.buffer[mod(tm.Minute*3+3,180)]=8; // minutes green

        int x=((hour12)+(tm.Minute/12))*3;


        WS2812OutBuffer(rgb.buffer, 180,1); // 60 LEDs