Cheap and Simple WiFi with ESP8266 for the FRDM Board

How cool would it be to add WiFi support to any projects or IoT? Why not using WiFi with a microcontroller which has only few KBytes of RAM and FLASH. For less than US$5? Dreams came true, and intrigued by an article at Hack-A-Day, I searched a supplier for that ESP8266 module. And this evening I have found the four ESP8266 modules I have ordered for $4.50 each from ElectroDragon in my mailbox. Of course I did not want to wait for the week-end, so I hooked it up to my FRDM-KL25Z board.

ESP8266 Module

ESP8266 Module for US$ 4.50

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How NOT to Solder Headers on a Board

There are two basic strategies in teaching:

  1. Teach and show how things should be done.
  2. Teach and show how things should NOT be done.

I usually do the first method. But there is a lot of value in the second method too!

When I asked all student groups to solder the headers on the Freescale FRDM-KL25Z board, I received one report that the board does not work any more. A quick inspection of the board showed this:

Soldering the FRDM Board Headers

How NOT to Solder the FRDM Board Headers

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Enabling/Disabling FXOS8700CQ Device Needs a Delay

Found an interesting behaviour with the Freescale FXOS8700CQ on the new Sumo Robots (see “Sensor and Communication Shield for Sumo Robot“): when enabling the accelerometer/magnetometer, it actually did not work:

Failed to Enable FXOS8700 Accelerometer

Failed to Enable FXOS8700 Accelerometer

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BBQ Smoker Monitoring Robot

I have to admit: I’m not a vegetarian. I love BBQ, and no offense to vegetarians! Today is perfect day for another BBQ session, and this time I plan to enhance it with electronics. No, not eating electronics, but doing BBQ with a little DIY electronic helper. There are different ways to cook meat on an open fire pit, and each region of the world has its own way to do it. Traditionally, in my area we are ‘grilling’ the meat: high temperature, for a few minutes, done! I like that ‘fast food way’ too, but there is an even better version: Slow food smoking!

I’m gifted that I had the opportunity to experience the Texas BBQ culture: slowly cooking the meat, at low temperature, and ‘smoking’ it: Cooking the meat around 80°C prevents that it gets dry (because the water does not vaporize, see this article on Wikipedia). There are different ways how to do this, but I love the way how it is done at the Salt Lick in Austin/TX with an open fire pit:

BBQ Pit in Austin Texas

BBQ Pit in Austin Texas

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Sensor and Communication Shield for Sumo Robot

The semester started last week. Ideally I wanted to have the boards for the new S robot (see “Zumo Robot with WiFi and GPS“) ready in the first week. But our manufacturer was not able to get the four-layer boards with parts populated and delivered in that time frame. Until the new boards arrive, we have anyway plenty of things to cover. One thing is to build a prototype shield to host several distance sensors, nRF24L01+ and Bluetooth transceiver:

Sumo Robot with Sensor Shield and Sensors

Sumo Robot with Sensor Shield and Sensors

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LED Clock with Kitchen Hot Pan Protector

When I showed my 60 NeoPixel LED clock prototype to my daughter and her girlfriend, and they both wanted to have one right away :-). Well, that clock was just a proof of concept, with lots of temporary wiring. So I decided this week-end to beautify it and to make it look nice and clean(er). There is nothing like a week-end project with adding a few more LEDs and features :-).

Adafruit Neopixel Clock with 60+24+12 LEDs

Adafruit Neopixel Clock with 60+24+12 LEDs

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Zumo Robot with WiFi and GPS

It always takes longer than expected: actually 4 weeks from the first board out of the reflow oven (“First New Zumo Board out of the Reflow Oven“), until I have it working on the Pololu chassis. But now I have a mobile Robot with WiFi, GPS, Bluetooth, nRF24L01+ and all the stuff I have dreamed off 🙂

New Zumo Robot

New Zumo Robot

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Adafruit NeoPixel Clock with 60 LEDs

After the problems with level shifters (see “First Adafruit NeoPixel Blinks with the FRDM Board“) I received the ordered 74HCT245N. Put it on a bread board, wired it up, … only to find out that the device gets very hot… turned off power, and realized that had the device put in with a wrong orientation 😦 oh darn! That’s why I always order things like that in quantities of 3 or more :-). Corrected the mistake, and things are running (or blinking) again 🙂

74HCT245 Wiring for WS2812

74HCT245 Wiring for WS2812

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First Adafruit NeoPixel Blinks with the FRDM Board

LEDs are getting smarter these days. An amazing example are the WS2812(B) or ‘NeoPixels’ from Adafruit: RGB LEDs with a built-in constant current controller and shift register! With a single wire data wire hundreds of RGB LEDs can be controlled. Exactly what I need for a project I had in mind for a very long time. So I ordered a bunch of different LEDs from Adafruit to experiment. Exactly the right thing on dark and rainy week-end. And the result is, well: bright and colorful 🙂

Adafruit NeoPixel LED Ring

Adafruit NeoPixel LED Ring

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UART printf() for the FRDM-K64F Board and Kinetis Design Studio

I had great plans for this Saturday: to work on really cool project. But as so many times, things turned out to be different. Maybe you have read my recent posts about printf()? A colleague wanted to use that article to the same thing with the Kinetis Design Studio on the FRDM-K64F board. I used the FRDM-KL25Z board, so I expected this to work out of the box for him too. Well, turned out that I was wrong about this, and my Saturday was used for debugging and googling about a printf() problem 😦

While things work as expected for the FRDM-KL25Z (ARM Cortex-M0+) and using the standard GNU GCC ARM Embedded from the launchpad, the application traps on the K64F (ARM Cortex-M4F) in initialise_monitor_handles() with KDS:

Trap in initialize_monitor_handles()

Trap in initialize_monitor_handles()

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