Category Archives: Embedded

5V Generation from V_IN on the Freedom Board RevE

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The Freescale Freedom boards like the FRDM-KL25Z feature an Arduino header so I can stack shields on it. Unfortunately, the Freedom board does not generate 5V if not connected to the USB cable. This makes it not possible to be used with many shields like the Adafruit Motor Shield: such shields expect that the Arduino board is providing 5V through the Arduino header (Pin 10 on J9 on the FRDM-KL25Z). So I had to do hardware changes to generate that 5V if I used my board disconnected from USB, e.g. running from batteries through V_IN (pin16 (P5-9V_IN) on the FRDM-KL25Z.

J22 with Capacitors on FRDM-KL25Z RevE

J22 with Capacitors on FRDM-KL25Z RevE

The good news is that the Rev.E of the Freedom FRDM-KL25Z board has now a header J22 to make things easier:

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Using the HC-06 Bluetooth Module

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After my first post using a Bluetooth module, things have evolved a bit. The challenge with these Bluetooth modules is: they look the same, but having different firmware. I did not fully realize that until I have ordered another bluetooth module from dx.com:

DX.com Bluetooth Module (HC-06)

DX.com Bluetooth Module (HC-06)

That module comes already on a carrier, so I assumed I can use the same driver as for my other module. I was wrong :-(.

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Tutorial: Arduino Motor/Stepper/Servo Shield – Part 3: 74HCT595 Shift Register

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For many projects, I have one common problem: I run out of I/O pins on my microcontroller :-(. Luckily, I’m not alone, and the industry has created solutions for this kind of problems. One is to use a shift register as the 74HCT595/SN74HC595 which gives me 8 extra output pins. All what I need to spend are are 3 GPIO pins. Not a bad deal: I spend 3 pins and I get 8 (or multiple of it) on return :-).

So why do I say this for this Arduino Motor/Stepper/Servo Shield tutorial? I have asked in this earlier post with a poll for the next topic (relais, motor or command line interface). Right now votes are mostly for relay. But before I can do relay (or DC motor), I need to first cover the 74HCT559. So here we go to have you ready for the next tutorial 🙂

Arduino Motor Shield

Arduino Motor Shield with 74HC595

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Bricking and Recovering FRDM-KL25Z Boards: Reset, SWD Clock and Low Power

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I’m working with a student on building a small autonomous robot platform, based on the FRDM-KL25Z board. We integrated new software modules, compiled and linked, and then downloaded the application to the board. While debugging and stepping through the application startup, I had this:

The Debugger has lost communication on connection

The Debugger has lost communication on connection

Outsch! That’s not good. Even worse, trying to connect again to the board failed :-(. What happened?

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Adding Quadrature Encoder to the Zumo Chassis

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The Pololu Zumo chassis is nearly perfect for my needs: it is small and compact, and neatly works with the FRDM-KL25Z board. I’m able to use it for line following or maze solving. But it lacks a position (quadrature) encoder on the wheels which is either very useful or even required for the lecture assignments for my next class. The Pololu Zumo chassis mainly has been designed for Robot-Sumo competitions, where such quadrature sensors are not really needed. Pololu offers optical quadrature sensors for their 42×19 mm wheel which I used in this project. So why not adding these sensors to the Zumo chassis?

FRDM-Robot with Quadrature Sensors Mounted

FRDM-Robot with Quadrature Sensors Mounted

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Tutorial: Arduino Motor/Stepper/Servo Shield – Part 2: Timed Servo Moves

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You have decided: More than 52% voted in Part 1 that the next topic should be Timed Servo Moves. So here we go :-).

This is about how to move the servos over time, instead of moving it to the given position as fast as possible. I’m using a linear approach here: moving the servos linearly over time.

Moving Servo Motors

Moving Servo Motors

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Julier Formula Student Electrical Race Car as Television Star

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Yesterday the local television station Tele 1 collected film material for a report about the “Julier” Formula Student team. The team did run more tests on the Alpnach air field, and this time the weather was much better compared to the last weekend. With the risk to get sun burned 😉

Until Tele 1 publishes the material, I have here pictures from the scene, the team and the car.

Camera, and Action

Camera, and Action

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Julier 4WD Test Drive in Alpnach

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While weather is bad and Switzerland suffers from record high rain water levels, the Formula Student “julier” team was testing their race car this week-end after the rollout. This time to test the 4WD with more torque. Plus water-resistance ;-). So here are impressions, pictures and a video from this week-end:

Julier Formula Student Race Car

Julier Formula Student Race Car

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Tutorial: Arduino Motor/Stepper/Servo Shield – Part 1: Servos

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This post starts a small (or larger?) series of tutorials using the Arduino Motor/Stepper/Servo Shield with the FRDM-KL25Z board. That motor shield is probably one of the most versatile on the market, and features 2 servo and 4 motor connectors for DC or stepper motors. That makes it a great shield for any robotic project :-).

Arduino Motor Stepper Servo Shield with FRDM-KL25Z

Arduino Motor Stepper Servo Shield with FRDM-KL25Z

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Character LCD with 4 Lines

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Character LCD’s (like 2 lines with 16 characters each) as in this post are easy to use. Much easier to use compared to full graphical LCDs.

The ones I’m using have either 1 or 2 lines, but I saw that there are 4 line displays too. So far my LCD component only supports one or two lines.

4 Line LCD

4 Line LCD (Source: Ezequiel Bazotti)

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