Recent Updates

JLed – a library to provide painless control of LED blinking, breathing and fading effects.

Jan Delgado has updated his JLed library a couple of times over the past week.  The first update was a change specific to the ESP8266 to improve the 8-bit to 10-bit scaling, so that LEDs now reach full brightness.  The second change is the addition of a boolean return value to the Update() function to indicate whether the target effect is still active, or has completed.

OpenMQTTGateway – Bidirectional gateway for the integration of 433MHz, BLE and IR devices with MQTT.

Florian has made a small change to his OpenMQTTGateway to make the “TRACE” function compile-time selectable, in order to reduce the overall code size for those who don’t use it.

IRremoteESP8266 – A library to enable IR send and receive on the ESP8266.

Mark and his various contributors (including “crankyoldgit”) have added initial support for Elektra, Samsung and Whirlpool air-conditioners and experimental support for  Coolix and Lutron.  There are also additional fixes for Mitsubishi A/C and the IRMQTTServer code.

Esparto – A rapid development framework for ESP8266

Phil Bowles has added MQTT username & password functionality to his (relatively new) rev-2 version of Esparto, as well as fixing a couple of minor bugs.

 

esp8266-weather-station-color – An ESP8266 and ILI9341/XPT2046 based weather display.

Daniel and Marcel continue to update the colour weather-station display, with fixes for some I18N and WiFi issues.

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YAESPK (Yet Another ESP Killer)

Seeed Studios is currently advertising the Air602 WiFi module at a price of $1.90 for single unit quantities.  The Air602 is tiny (smaller than a postage stamp and smaller than the ESP8266), but before you whip out your credit card to order half a dozen, you need to realize that one reason it’s so small is that there is no on-board antenna and no antenna socket, just a normal, edge connect pin on the board.

Block Diagram of WinnerMicro W600This thing in not an ESP of any variety.  It is based on the WinnerMicro W600 SOC, which has a Cortex M3 core.  The block diagram looks very impressive (although at the moment, the WinnerMicro web site is much less impressive and is doing an excellent impression of a honey-pot/tar-pit trap for unwary browsers), with dual UARTs, I2C, SPI and I2S interfaces, an RTC and hardware crypto all baked in.

The Air602 module has a limited number of pinouts (more than the ESP-01, though), so the available interfaces are fairly limited.  There are 12 pins available, but with two ground pins, one 3v3, one antenna and one (input only) reset, that leaves only 7 pins available for I/O and those seem to be split between the two UARTs as primary (with the SPI bus as alternate use) and the single GPIO-8 available as unassigned.  I’m guessing that the reason for the two pins being assigned to GND is an attempt to make it easier to add a micro antenna socket (the grounds are either side of the antenna pin).

The SDK zip is available from Seeed’s site and, given the current, sloooo-o-o-w state of the WinnerMicro web site, that’s where I’d advise you to go for more info.  The module itself seems to ship with LUA and an AT command set implementation as standard (again, shades of the original ESP-01).  Seeed also have a WiFi development board, based on the Air602 module, for only $2.90, which is a give and take proposition.  It has an antenna (big plus) and the PCB is made to plug directly into a USB socket, but only 5 of the W600’s IO pins are available as through-hole connections.

Get it while it’s hot!

If you happen to be resident in Japan and if you’re thinking about interfacing to an ESP8266 via Google Home, then you’re in luck …but only for the next two days.  Bic Camera is having a sale between the 22nd and 24th (of September, 2018) with some specific items heavily discounted.  One of them is the Google Home Mini at ¥3,240 (with free shipping inside Japan).  Not only is this a really good price (especially for the land of the rising yen), but you don’t even need to trust some intermediate, dodgy web site with your credit-card details; this is Japan, so you can just stroll down to your nearest “combini”, type your order number into their terminal and then use the printed invoice it produces to pay cash at the counter.  The next step is to sit back with a couple of beers and a good book while you wait for the Takkyubin to knock at your door.  Yappari, Nippon wa sugoi, desune (tokidoki!).

A non-trivial ESP8266 project

If the name Aidan Ruff rings bells with you, it’s probably because of the frequent mentions he receives on Pete Scargill’s blog and for his designs of their “Hackitt & Bodgitt” series of ESP-based hardware (Aidan’s board designs, such as "Hackitt & Bodgitt" Nextion Display Boardthis ESP12 board aimed at supporting a Nextion display, are especially useful for general purpose ESP8266 development and he makes the files freely available on-line).

Aidan is in the process of having an old farmhouse (in an olive grove in Spain) rebuilt and, because there are no mains services (electricity or water) available, has embarked on what, to most of us, would be the non-trivial project of providing enough solar (and possibly wind) power and enough battery capacity to provide summer cooling and winter heating without having to resort to the use of a generator during prolonged, adverse weather conditions.  His outline plan on how he intends achieve this (along with some impressive floor-plans) are available on his “Off Grid in Spain” blog.

Of more specific interest to ESP aficionados though, is the solar-tracking sub-project he’s put together to ensure that the (MPPT) output from his panels is maximized by adjusting elevation and direction.  The tracker controller is an ESP8266-ESP12 of course, but with a novel twist.  Instead of using the tried-and-tested optical tracking method (with its inherent problem of “hunting” on overcast days), Aidan has hooked up a GPS receiver to the ESP and uses a combination of the precise time and positional data to compute where the sun should be in the sky at his particular location (whether it’s hidden by clouds, or not).  The ESP communicates via MQTT (but also has an embedded web server and an attached OLED display panel), which means that, with additional data from a connected weather station, Aidan can add features such as having the solar panels rotate down to lie flat when the wind speed exceeds a pre-set limit.

The initial prototyping and testing of the two-axis, linear actuator based tracker is already completed and Aidan has put up his board and mechanical design files and a couple of videos on a Hackaday I/O project page.  Unfortunately, at the time of writing, the ESP code doesn’t seem to be available either on that page or from Aidan’s GitHub repository, but despite that, it’s definitely a project worth watching (tracking?).

Free SBCs

Linux Gizmos is currently running its yearly round-up of SBCs, along with the customary questionnaire/competition, giving you the chance to win an SBC or a shield/add-on board for free.  So, if you’re interested in getting hold of an SBC as a gateway for your network of ESPs, head on over there and answer a few questions.  I make it roughly a 1:120 chance of winning (based on their stats from last year), which is a lot better than the lottery.

 

 

u-blox produced ESP32 has FCC approvals

Update 15th May 2018 — Between writing the first draft of this article and pushing the big red “Publish” button, the prices for all of the items mentioned here have already changed (downwards), so please refer to the u-blox AG online site for the latest, up-to-date pricing for your area.

u-blox AG, the Swiss company famous in hobby circles mainly for their excellent (and cheap) little GPS modules, have started selling two new standalone WiFi modules, the NINA-W101 (external antenna connector) and the NINA-W102 (module mounted antenna).  u-blox AG's NINA-102 moduleThe W101 is priced at $US 8.75 and the W102 is $US 9.48, direct from u-blox in bulk (250, or more).  While that price is fairly competitive for an ESP32 module (assuming that the one-off price isn’t too far out of that particular ballpark), the cost of the development board is a bit excessive, at US$ 99 (again, available directly from u-blox AG’s on-line shop).

The antenna on the W102 model (shown above) is neither the older SMD-chip type nor the PCB trace type.  It seems to be a custom made planar inverted-F antenna (PIFA), distinct from the existing ESP modules in that it stands over 1mm higher than the RF shield on the module.  u-blox AG provide suggested sizing for orientation and ground-plane sizing in their datasheet.

The NINA-W10 series data-sheet makes interesting reading and, although the u-blox document doesn’t come right out and say “this is an ESP32”, it doesn’t keep it a secret, either (on a couple of the pages there’s a footnote reference saying “See the Espressif ESP32 Datasheet for…).

Although neither of these modules is particularly hobbyist friendly (ref the solder-side of the W102 module in the photo, above), many IOT designers will be excited to see that they are FCC approved for the U.S. (and RED/FCC-equivalent for many other countries, too) and that u-blox AG offer support for integrating the modules into an end product as a “grantee” (if you understand the FCC process that last part will hopefully make sense to you).

In the same “Short Range, WiFi” product category are the closely related NINA-W131 and W132 products which appear to be almost identical, except that Bluetooth isn’t available.  Details on these two modules are a little sparser than the W101/102 variants.

 

Driving WS2812 LED strips with the ESP8266

There’s a really captivating article on Tweaking4All illustrating the various effects (firelight, bouncing-balls, chasers, etc) that can be easily reproduced with the common WS2812, addressable, RGB, LED strips, available from just about every vendor out of the Middle Kingdom.  Although the article is a couple of years old and is aimed at Arduino hardware using the FastLED or NeoPixel libraries, the routines are, for the most part, directly transferable to the ESP8266 (both libraries are available for the ESP when using the Arduino framework).  When used with the ESP8266 though, there are a couple of pitfalls which you need to be aware of:-

  • 3v3 vs 5v voltage levels
  • The ESP8266 wireless housekeeping requirements

The first is something you need to pay a little bit of attention to, in order to prevent damage to the ESP GPIO pin.  It’s very easy to isolate your ESP8266 from the WS2812 5v supply voltage and provide a low impedance drive for the WS2812 bus at the same time, using a cheap, PNP transistor in emitter-follower configuration.  An emitter-follower is a non-inverting buffer, which provides a medium to high impedance on it’s input (so it doesn’t place any significant load on the GPIO pin) and presents a low impedance output (meaning it can drive more current than the ESP GPIO pin can alone).PNP Emitter Follower  Unlike the more traditional common-emitter transistor circuit, the emitter follower doesn’t amplify the input signal at all; in this circuit it is acting as a switch, but while the output from the GPIO is switching between 0v and 3v3, the output of the emitter-follower is switching between 0v and 5v.  Thus this simple circuit not only protects your ESP from damage, but also provides the correct voltage swing for the WS2812 data bus, too.  Almost any common, small-signal PNP transistor (2N3906, BC560) will work in this configuration; specific type is not too critical.

The second issue is the common watchdog-timeout issue which plagues applications which spend too much time in tight, time-critical loops without allowing the ESP8266 time to attend to its WiFi housekeeping.  The answer in this case is fairly simple …just put a couple of calls to yield() into the code in strategic places (one in the top of the loop function and another following the call to showStrip() , in whichever example code is being used, worked well for me).  Unless you’re doing something insanely complicated and insanely fast, you shouldn’t notice any visible difference to the display.  If you are running something i-comp and i-fast, you should bump the ESP8266 speed up to 160Mhz to handle it, anyway (“board_f_cpu = 160000000L” in your platformio.ini file); you don’t need to make any changes to the code to handle the faster CPU clock.

With these two issues addressed, you should be able to run any of the examples from the Tweaking4All site.  You have the choice of using either the FastLED or NeoPixel libraries and the Tweaking4All collection comes with all of the examples duplicated across two directories, one for each library.


Other Options

There’s also a second version of the FastLED library available from Cory R. King which adds DMA output for the ESP8266 for a smoother, flicker-free output.  Note that DMA hardware in the ESP8266 uses pin-3 (which is the UART RX pin) as the output …so no matter which pin you define in the display code, it will always use pin-3.

In addition to those already mentioned above, Makuna (Michael C. Miller) has also done a lot of work on optimizing WS2812 driver code specifically for the ESP8266 and ESP32 processors with his NeoPixelBus library.  It has multiple interfacing options (DMA, UART and bit-bang) available.  DMA is the default (and recommended) operating mode.  Users have reported that, for the ESP8266, the NeoPixelBus library is the most robust and reliable method for driving addressable LEDs when the WiFi must also be in use.  Although Michael’s examples are quite comprehensive, you may find yourself with some coding to do if you want to convert all of the Tweaking4All demos to run using this library.