The cool thing with the Freedom board is: there are many exciting Arduino boards out there which want to be used with the FRDM-KL25Z. I have spent most of my last week-end with creating a little black beauty:
When I was looking for some nice DC motors with quadrature encoders for my next lecture project, I stumbled over the Pololu web site which had *exactly* the DC motors I was looking for. And their Zumo Robot Robot Kit was something which attracted my eyes.
I always joked 🙄 about women shopping habits. But my wife is right: If it is about electronics, I’m not different at all 😀
That robot is smaller than 10 cm on each size, so it qualifies as a Mini-Sumo. Although I have a different purpose in mind for my robot…..
Chassis and Motors
I ordered the chassis with two 75:1 Micro High Performance Metal Gearmotors which enable the chassis to move about 50 cm in a second. The chassis includes a battery compartement on the bottom for 4 AA batteries (so up to 6V):
💡 I did *not* follow the Pololu instructions to solder the motor with the Arduino shield: instead I used flexible wires to attach the motors to the board. That allows me to change motors or disassemble the kit in a much simpler way.
The Arduino board comes with a few parts unpopulated (Buzzer, Headers, Switches). The board features a tiny (but powerful) Dual Full-H Bridge, a Buzzer, Battery Voltage Sensing and a I2C Accelerometer+Magnetometer sensor:
The FRDM-KL25Z needs to connected ‘face down’ to the Zumo board. I plan to layout an intermediate PCB with my to-be-added hardware. But for now I’m using normal breakable header rows as ‘interconnection’. This is necessary as otherwise the Freedom board is very close to the Zumo board components:
The FRDM-KL25Z is powered from the batteries through P5-9V_IN. But: the Freedom board only generates the 3.3V from P5-9V_IN, and but not the needed 5V to the header (see this post). That 5V is needed by the Shield. So for now I’m using a rather bulky DC-DC converter and supply the needed 5V from the battery to the USB 5V supply line, until I can replace the DC-DC converter with a smaller one. At least everything is working now :-).
Software, and Next Steps
The software in CodeWarrior with Processor Expert is ready for most parts. Motors (speed/direction), LED’s and Buzzer are working. Magnetometer/Accelerometer and Battery Voltage Sensing are in progress. The current software is available on GitHub with all the Processor Expert components. And: I have a Bluetooth module ready to integrate, plus I want to add a line scanning module too. So enough fun for a couple of dark nights and week-ends :-).
Happy Zumoing 🙂