Big Jake (the toy tractor) is now almost mutated to “Electric Big Jake”. The build seams fairly stable (tractor was able to carry me), and I managed to put back the top cover on the tractor. In the movie you see “Electric Big Jake” test-driving on a stool (I was only giving about 1-10 Volts to the motor) , you also see how crappy all that plastic stuff is, and how the back wheel wiggles.
Here is a short update of the e-tractor project. I managed to mount the motor, add a hall sensor based throttle to the motor controller , and, … well … , OK damn! I fried that motor controller 
. And no, everything was wired correctly, it was just stupidity: When I was testing the throttle with the motor, the controller got in contact with a tool, and bang, short circuit. So the lesson learned here: if you make a mess clean up the mess …. anyway, replacement is ordered.
Oh, by the way: chain and gear fitting with the gear that came with the motor are from a pocket bike 
.
OK, the MY1016 DC motor arrived, and I couldn’t resist test-driving it . Well, it is fast (schnell) though. And, since there where some complaints about that “krokoklemmen” which I used for the small motor yesterday, here a short updated in pictures …
My son and I are planning to add electric drive to an children’s tractor (which normally is powered by pedaling) . Thus, a high power motor controller is needed (since a 250Watt/24V/14A engine is already ordered). Pololu offers a range of different high power controllers, and I decided to by the 18v15 (there is also a very well done user guide online).
This controller is able to operate a single motor with up to 30V at continuous 15A. It allows to adjust the speed from a MCU through RX/TX, or from a RC or analog source like a potentiometer. The controller and the batteries (two Panasonic 12V/7.2A lead-acid batteries) arrived today, and I wasn’t able to resists giving the controller (and one of the batteries) a first try. For the motor controller, a “Simple Motor Control Center” software is available which allows to configure the controller through it’s build in USB interface. Since the program is based on mono, a Linux version is available as well (mine required to run with root privileges, otherwise it refused to connect to the controller). The software gives you a quick start, and allows one to configure e.g. which source is used to control the motor speed. Well I decided to go for the potentiometer. Everything worked very well, and I am looking forward to test the setup with two batteries and the real engine (which I expect to arrive to morrow). See the pictures and movies for some impressions of how the setup looks so far.
There is an article on Mikrocontroller.net (english translation)which describes how to use the TI Launchpad as an AVR programmer (the included MSP430G221 is goog enough for that!). The firmware they offer for download allows one to program an AVR chip through the avrdude tool. Nice job I’d say.
While making my first “cap” for the Beaglebone (working on a YWasp cap), I learned the hard way that not all pins on the expansion header of the bone are “good” pins. After putting the cap (which I worked stand alone fine) on the bone, it refused to boot! When taking the MSP430G2553 out of its socket (while leaving the cap installed), the bone booted again. Then when placing the MSP430 back in the socket with the bone already running and booted (yes, yes I known …), the cap also worked.
So I put the cap and the bone away, until yesterday a colleague of mine, who knows the Beaglebone schematics very well, came up with the point, that there are some “bad” pins on the expansion header which are more ore less unusable. This is because the pins from the CPU which determine the boot-sequence of the ROM-code boot-loader are connected to some of the expansion header pins! Thus, if you fiddle around with this pins, it is very likely that you change the boot-sequence to something useless (e.g. tell it to boot from a serial line).
Matching this pins with the ones my cap used, it turned out, that I was about to use four of the 16 boot configuration pins. After re-wiring those pins, the bone booted fine again, and the cap worked also. The “bad” pins are shown in the schematic below.
Beaglebone Boot Configuration
This is just a quick little Easter hack. My wife brought in two cute little glass Easter bunnies lately, and they really demanded for a mod. Well then. The bunnies got a blue LED implanted each, the LEDs where connected to a MSP430G2231 MCU, and the MCU is driven by a small firmware which pulses the LEDs through a PWM. See the result in the blow movie (pure quality, the pink bunny doesn’t look like glowing so much, but it does):
I wrote up a little HOWTO which shows how to drive a MSP430G2xx MCU standalone (without Launchpad). It also shows, how to use a Launchpad for in circuit programming through only three lines (Spy By Wire). In the HOWTO, we first will have a look on the most minimal set-up needed, to run a MSP430 value line MCU outside the Launchpad. Then we will detail a little more on how to supply a regulated voltage to the device, and last we will see, how the Launchpad could be used as in circuit programmer.
Test setup
Over at Universite de Mons, they have an interesting firmware modification for the BusPirate: it allows to sniff Zigbee (or any other 802.15.4 based) traffic. From their webpage:
The Bus Pirate 802.15.4 Sniffer is a replacement firmware for the Bus Pirate that allows to capture IEEE 802.15.4 (~ ZigBee) traffic, using Microchip’s MRF24J40 transceiver. The MRF24J40 transceiver communicates with the Bus Pirate through a Serial Peripheral Interface (SPI).
Tonight I decided to end the breadboard mess for the MSP430 YWasp by soldering a little nRF24l01+ shield for the Launchpad together. The nRF24l01+ with its external antenna looks somehow impressive on the Launchpad . The Launchpad with the MSP430G2553 is communicating happly with the STM32VL Discovery based YWasp prototype. The nice thing about the Launchpad variant is, that it comes already with a USB-to-serial converter, so you can directly plug it to your Linux box and use “/dev/ttyACM0″ to communicate with the counterpart YWasp.
Last Comments