ESP8266: NodeMCU Motor Shield Review

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If you want to engage with your ESP8266 into robotics there is now an almost ready-to-go solution: the NodeMCU Motor Shield. If my research is correct then it was the Doctors of Intelligence & Technology (http://doit.am/) who created it and also are offering some LUA code to get started. This post shares my experience with the motorshield and also with a two engine “Smart Car” kit that nicely combines with the motorshield.

Motorshield

If you want to drive motors with your ESP8266 you have to be careful. The General Purpose Input/Output (GPIO) pins of the ESP8266 (as well as the similar Arduinos) don’t allow you to draw the amount of current required for a motor. But how to do that? You could build something on your own by using a few electronic components (transistor, capacitor, etc) or you could just pick something off the shelf that does exactly that for you. That’s where the Doctors of Intelligence & Technology and their motor shield comes in. It is designed to carry a NodeMCU V1.0 on its back. Note: the motor shield won’t fit for a NodeMCU V0.9! It has convenient terminals to attach two two-ways motors (or according to some source one stepper motor). It also has terminals to attach the power source that drives the motors and the NodeMCU. And as a clever addition you can decide to have just one power source for both motors and NodeMCU by setting a jumper accordingly.
One of the two terminals (Vin for NodeMCU) can be cut off with a power switch which saves you from taking out the batteries.
Besides the terminals there are also male pins which lead out GPIO 0-8 (in NodeMCU terminology), the reset pin, the analog/digital converter, the UART pins and the SPI pins.
NodeMCU V1.0 Powershield
A sign on the PCB makes it easy enough to plugin the NodeMCU the correct way: just make sure that the antenna of the ESP8266 and the antenna symbol on the motor shield are on the same side.

Smart Car Kit

The Smart Car Kit is the ideal companion for the NodeMCU if you want to get started into WiFi controlled cars or robotics. Some vendors even sell it in one big package for about USD $22 (see here). It comes with 2 two-ways motors with reduction gear, two main wheels and one support wheel, a chassis, a battery pack for 4 AA cells and additional screw driver.
You can put everything to getter within just about 15 minutes once you have figured out where the parts have to go. I only had two issues with the kit: while you might be able to attach the wires to the engine without soldering I would recommend that you do this with a soldering iron. The other (bigger) problem was the supporting wheel. It turns easy enough around the axis of the wheel itself but the z-axis which should adjust when the car makes a turn is not working so smoothly. This can have the effect that even if both motors go at the same speed the supporting wheel is stuck in a weird position and keeps your car to pull to one side. I solved this by using some duct tape and fixing the wheel at the “forward” position. This might be suboptimal for turning but works good enough on smooth floors. It might be a problem though on soft carpets but I haven’t tried that.
The Smart Car Kit

Bringing it together: the WiFi Car

The next step was to put all the pieces (Smart Car, battery pack, NodeMCU V1.0 and Motor Shield) together. The holes of the motor shield fit perfectly into the holes of the acrylic chassis and the kit comes with enough screws and nuts to attach it. Also the battery pack can be screwed easily onto the chassis. The way I placed the components onto the chassis left only little space between the motor shield and the battery pack which made it hard to attach the wires with the terminals.

Programming the Car from the Arduino Environment

The inventors of the kit have sample code for LUA on their website. But I decided to try to program the car with the Arduino IDE. And that is really easy: 4 pins control the engines. Pins 4 and 5 (Arduino Terminology) control the speed of the engines with PWM in a default range of 0..1023 while pins 0 and 2 define the direction the engines will turn. 0 is backwards and 1 is forward but this might depend on who you wired the engines up to the shield. In my case I had to swap the wires of one of the two engines so a “1” would symbolise the same direction for both engines.
First I wrote a little Arduino sketch to test if everything was working alright and if I understood the interface correctly. From there I incrementally improved the code and I’m now able to steer it with any device with a modern browser, a built in accelerometer by just balancing the device in the direction I want to car to move. While it is still far from perfect it works surprisingly well: a javascript program reads out the accelerometer of the controlling device (e.g. an iPhone) and sends AJAX requests to the WiFi connected Smart Car. These commands are then taken to steer the motors.
In this scenario a big part of the logic is in the javascript code. While this could be hosted on the ESP8266 EEPROM I decided to load it from an external server which makes it really easy to program: I only have to change the file on the remote server. The ESP8266 firmware remains unchanged for most of the time.
To connect to the device you only have to find out the IP that has been assigned to the NodeMCU. Then open that IP in your Smart Phone browser and move level your device to steer the car.
Here is a little video of that setup:

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Posted by squix78

51 comments

  1. Observation, you could pull the weather icons from the Weatherunderground server rather than host them yourself. I think they do-not apply any read quotas.

    Did embedding the icons in flash prove to be too great an overhead?

    1. Hi David. If I’m not mistaken these icons are from a 3rd party (which reminds me to put their credits up). So I’d have to host it somewhere anyway. I currently also only use uncompressed bmp format and I doubt that any reasonable person still has them around for normal use;-). And then: downloading has the advantage to be easier to change compared to embedding in the firmware… But it was a design decision. Comparing pros and cons…

    1. Hi Stephen. I plan to upgrade the plane spotter project to the color screen, so yes, it’s definitely possible. Just a question of time:-)

  2. Hi,

    I have a working esp8266 weather but the small LCD only.
    im trying this one as i have the exact LCD lying around. i saw the “settings.h” where values need to be changed. (i.e. wundeground API, country, city, etc).. the only one that i was not sure and I did not see any explanation was the ThingSpeak value.

    May i ask what is the purpose of the Thingspeak value? i tried to view it but I think its a private channel.

    Anyway, i uploaded it on NodeMCU and when i inspect the Serial monitor, i can get to the part where it downloads the pictures.
    Here is the last bottom lines on the Serial.
    There is a line that says “connection failed.”…. Im guessing it has something to do with the Thingspeak..or maybe something else..

    …….(lots of downloding lines here…………..)
    Downloading http://www.squix.org/blog/moonphase_L19.bmp and saving as /moon19.bmp
    Downloading http://www.squix.org/blog/moonphase_L20.bmp and saving as /moon20.bmp
    Downloading http://www.squix.org/blog/moonphase_L21.bmp and saving as /moon21.bmp
    Downloading http://www.squix.org/blog/moonphase_L22.bmp and saving as /moon22.bmp
    connection failed
    connection failed
    connection failed
    connection failed

    Loading image ‘unknown.bmp’
    File not found
    Loading image ‘/mini/unknown.bmp’
    File not found
    Loading image ‘/mini/unknown.bmp’
    File not found
    Loading image ‘/mini/unknown.bmp’
    File not found
    Loading image ‘/moon0.bmp’
    File not foundconnection failed
    connection failed
    connection failed
    connection failed

    1. Hi Glenn,
      The purpose of the Thingspeak channel is to display (say) your own local temperature and humidity. So I have an ESP8266 and BME280 sensor running that reports every 10-mins to thingspeak the current temperature and humidity in my garden. Therefore I provide the keys for my channel and it gets reported on the weather display. Ideally there would be a software (compile time) switch to remove that option.

  3. Please ignore the comment below.
    I was able to solve it. Apparently, the wifimanager didn’t connect successfully to my router, so i had to manually connect and put the static SSID and password.

    So its working now, yey! i can see the pictures and the icons properly.

    im still dumbfounded with the Thingspeak channel in the settings.h.
    May i know if that is really needed?

    1. Hi Glenn, I’m a program newbie and met same message from serial port, but I struggled for long time but cant overcome this issue, do you mind give me some suggestion?

      Thanks!

  4. Hi,
    Is there any chance regarding tutorial how to call bitmaps using WiFi connection?
    I want to prepare own set of icons but I don’t know how to use it in your script 🙁
    As well I have a question reagrding screen refreshing, as I see that is the issue when the time is updated and some pixels are not removed?
    Thanks in advance for help.
    Piotr

  5. Very impressive weather station, works great!
    If it could automatically update summer/winter-time, it would be absolutely perfect.
    Have fun with the beer 😉

  6. I was able to get this running, but wanted to mention a small issue I ran into. (Sounds like the same one Mike McRoberts references.) The bitmaps require more than 1M of SPIFFS, so if you were like me and had selected only 1M at compile time, you run out of space to download all of the bitmaps, and many of the moon-phase bitmaps will fail to download, or will be perhaps truncated or corrupted. I went back and changed to 4M (3M SPIFFS) in the IDE and was able to solve this. Still having a bit of overlay issues with the time updates, but as Daniel mentioned, the code may still need a little work.

    Thanks for all the effort on this…now to add some of my own tweaks!

  7. Hi Daniel,
    i tried to flash the script but i will receiving all the time the following error:
    *******************************
    In file included from esp8266-weather-station-color.ino:34:0:
    C:\Users\Jens\Documents\Arduino\libraries\esp8266-weather-station-color-master/WebResource.h:25:31: fatal error: ESP8266HTTPClient.h: No such file or directory
    #include
    ^
    compilation terminated.
    Fehler beim Kompilieren.
    *******************************
    I added the ESP8266HTTPClient-library to the Arduino 1.6.5 but there is still the same error.
    Do you have any idea what i can make that the script will runing?
    Jens

  8. Unfortunately Banggood.com are no longer stocking the 2.2 Inch Serial TFT SPI Display ILI9341 display! Can it be obtained from another supplier? Or can an alternative be used?

    I would like a bigger screen for my PlaneSpotter project so that I can enclose everything in a case with the lcd screen acting as a box top : )

  9. Dani, excellent! Built this over the weekend (preparing to teach another IoT class this week) and almost worked flawlessly (2.4″ TFT + Wemos D1 Mini). Couldn’t get the WifiManager to connect, tried a few different things then finally went manual mode. The 199: timeClient.updateTime(); would sometimes hang, changed the .h to use “us.pool.ntp.org” instead; didn’t do a lot of troubleshooting, was more in quick-fix mode. Maybe later this month I’ll try incorporating Neptune’s daylight savings code back into this (thanks btw for the link to that). PS will try to get some pictures with the kids doing projects over the session the next two weeks. Regards, Mike

    1. Mike, you stated that you changed the .h to use “us.pool.ntp.org”. What is the path/filename to that .h file?

  10. Dani,

    I’ve been adding some of my own enhancements to your original code for several weeks now, and thought I’d share some of my changes in case anyone was interested. I’ve posted these on GitHub if you’re interested…https://github.com/fowlerk/ESP8266-Color-Weather-Station-v8 .
    This version includes many enhancements to the displays (see the README on GitHub), along with Neptune’s enhancements for daylight savings time. The code could stand some clean-up, but otherwise seems to work well.

    Let me know what you think…I’ll post some photos of the displays when I get a chance.

    Keith Fowler

    1. Hi Keith

      You put some really nice things into the code! I knew that the WifiManager had this configuration UI feature but never got around to use it in my code. Now with your code I have a very nice example to use it;-). Thank you a lot for sharing! I just posted your fotos on Twitter and linked to your repository, I hope you don’t mind.

      I am working ATM on a 2.4″ display with touch. This would allow to switch screens or similar…

      Dani

      1. Dani…I don’t mind at all, in fact I’m honored. One thing to note, which I pointed out in the README on the repo, is that I have added a few fields over the past few months that may (or may not) have made it into the Weather Station library for the Weather Underground functions. Not sure how exactly to go about getting those into the master. (You may even be able to spot these on some of the displays.) I did not put those library changes up on the repo.

        I’d also had my eyes on those touch-screens and had similar thoughts on using them to control the screen displays. I’m anxious to see what you end up doing with it. Your projects always give me more ideas to try ;).

    2. keith, can you ples tell me what i need to download in the the IDE program to set this up there are so many files i do not know what one i need ! thansk

      1. Andrew…yes, sorry for not making this more clear in the documentation. I’ve (mostly) just used libraries that others have contributed and were already referenced in Dani’s examples, but you’re right that the list has gotten relatively long and may take some digging to find all the sources. Give me some time today and I will add the links to the documentation on my Github repository.

      2. I have updated the README on my repository with info on the contributed libraries and links to make it easier to find these. Let me know if you have any other questions.

  11. Hey Dani and Keith, I just tried this out a few days ago and love it. Just wanted to confirm that when I tried to use Keiths’ version, it failed to compile due to the changes in the Weather_Station library. I would really like to try out this version if one of you could point me at the correct library.
    This was my first project with an esp8266 and I am really surprised at how powerful and easy it is to use.

    Kevin

    1. Kevin…yes, sorry, I knew that would bite someone. I really wanted to get the changes merged into Dani’s master library rather than start off on another branch. In the interim, I have uploaded the two changed library files for the Weather Underground components to a separate folder on the repo if you want to download those to (temporarily) replace the original ones in the Weather Station library. That should allow it to compile. Let me know if that doesn’t work for you. Hopefully I’ll figure out the right (permanent) solution to address the changes soon.

      Keith

      1. Thanks for the update Keith,

        I got the new code and everything works great. Now I just have to figure out how to make it work with a bigger screen, maybe 7 inch. My eyes ain’t what they used to be. 🙂

        Kevin

        1. Glad you got it working Kevin…and I know what you mean about the old eyes! I’m right there with you. I’m torn between the compact size and being able to read all the data displayed without my glasses ;). Let me know if you find a bigger option that works well for a reasonable cost.

  12. Dani…just made a pull request on your repository to add some of the changes I had made to your Weather Underground library. Let me know if you have questions or issues.

  13. Dani, I just made another pull request for some new updates to the Weather Underground client library. These include changes to support some additional enhancements I have been working on recently that display weather alerts (as per the WU API call “/alerts”), as well as the addition of probability of precipitation (PoP). I have uploaded a new version to my repository on GitHub that shows these additional enhancements (see the README for further details), along with screenshots.

    As always, let me know if you have any questions or issues, and best wishes for the upcoming holidays!

  14. Hi Daniel. I don’t like the Ardunid IDE because of the lack of debugging with breakpoints. Therefore, I’ve just started with VisualGDB and JLink debugger and ESP8266. I have quite some difficulties.

    Do you have any experiences with VisualGDB?

    By the way: I am situated near Zurich and I like your projects! Great work!

  15. I have been having a lot of fun working through the examples with your weatherstation library. I bought your kit, which was an easy way to get started with the ESP8266.
    I am working through the WeatherStationDemoExtendedDST, for some reason updateData is not firing every 10 minutes. updateDHT is working fine, fires every minute.
    I think this is where the problem is, it isn’t setting readyForWeatherUpdate to true. However, it looks exactly the same as your other examples.
    if (readyForWeatherUpdate && ui.getUiState()->frameState == FIXED) {
    updateData(&display);
    }
    Thanks for any help.

  16. Figured it out. Apparently you can’t attach two events to a single ticker? I created two tickers, and now it works.
    tickerUpdateData.attach(UPDATE_INTERVAL_SECS, setReadyForWeatherUpdate);
    tickerUpdateSensor.attach(60, setReadyForDHTUpdate);

  17. I have problems getting it to run with Arduino 1.8.1, esp8266 2.3.0 board plugin and an SPI display. I have to slow down SPI to 250 kHz, otherwise I get all but pixel trash. But when I set OLEDDISPLAY_REDUCE_MEMORY I get a blank screen.

    Do you know of any problems with given setup? Can you recommend a good working combination of Arduino IDE, ESP plugin and SPI settings?

    1. I am a bit confused: which project are you referring to? The OLED Weather station or the color weather station which uses an TFT? Since you posted this in a Color Weather Station post I assume you are referring to the color code? But why then use the OLEDDISPLAY_REDUCE_MEMORY? Can you share a gist which shows your ino file?

      1. I’m sure, I posted that to “ESP8266: SSD1306 Oled Library Release”. 🙂

        Well, I’m just using your examples for the SSD1306 driver. Using a Wemos D1 mini R2 and “SSD1306Spi display(D0, D2, D8);”

        I had it working some weeke before. In the mean time I updated a lot of software, including IDE and board definitions.

        So, there are few choices left: the software combination I have is broken or D1 or display are broken.

        Can you or anyone else report that Wemos D1 mini R2, Arduino 1.8.1 and esp8266 2.3.0 are working with this SSD1306 library (unmodified)?

        Thank you!

        1. I’m still not sure, if my hardware or software combination is broken. But I finally got it all working. Key was reducing SPI speed. In SSD1306Spi.h we have a SPI.setClockDivider (SPI_CLOCK_DIV2), which means 8 MHz. It seems, the (just my?) display can’t handle that, I get mostly pixel garbage. If I reduce that to SPI_CLOCK_DIV64 (which means 250 kHz), it all works. I can even skip the yields() in SSD1306Spi.h’s display() routine. And I can get some speed back with replacing the SPI.transfer-loop for non-double-buffer cases with “SPI.writeBytes(buffer, sizeof(uint8_t) * DISPLAY_BUFFER_SIZE);”

  18. Thanks for making this template availble in the public domain. It has proven to be very valuable. As an improvemnet, would it be possible to have the NodeMCU pin assignment names on the PCB board, similar to the arduino one.

  19. I am having problems with the Weather Station. First screen (time) works well. Second screen says “N/A C”, Third scrren shows N/As, Fourth screen (temp, humid) works well. I have tried installing the latest github code and it doesnt solved the problem. Any tips?

  20. I have bought the Weather Station on Amazon. It came with a DHT11 in a board with a pull up resitor. I am following the pdf with instructions. When pluging this board, the figure at the pdf looks like inverted. My litthe dht board is (from left to right): data, vcc, gnd. It took me a while to figure out this. Also, by printing the read temp and humid values, I saw half of them come as nan. Any tip for improving this?

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