Mr Robot has entered the building

Today I finally got the Mr. Robot, ordered last week. This little kit will form a base for many joyful moments in future. The Mr. Robot is basically a 4x4 car body with two electric motors. The steering done just as in a Bobcat; braking (or free-wheeling) other side while running the other.
The box contains all (!!) the parts in small plastic bags and a nice instuctions manual in Chinese or Japanese. Fortunately the Google found instructions also in English. Of course, it is a shame to use the instructions at all, but luckily the assembly required also some craftsmanship:) As a nice bonus, there were two extra gears to front or rear axles and quite a few nuts with vinyl locks (so tight that I did not actually dare to use them).

The cheap price of the kit, 19€ could be seen on many parts. For instance, the body and parts that hold the drive shafts required quite a lot of fine tuning with pliers to make the transmission work without too much friction. Bolts and axles were also made from a bit soft metal, but none of them actually broke. Overall, the assembly was easy and resulting car is of better quality than expected.

Almost done. Oops, forgot to add back the two bolts to bumper, which were removed during assembly to make room for pliers holding the axle while tightening the tires.

The three AA rechargeable batteries inserted just to test that the mechanics and motors work. I could not find specs for the two motors, but fortunately they are replaceable. What worries more is the mechanics, if it bears even the current power capabilites.


The front transmission system required some care, as the metal frame at the inner end of drive shafts was not correctly aligned. The end result was that there were so much friction that left side motor could not turn the wheels. Now it works quite smoothly, but I had to leave the left front axle's bolts a bit loose. The chassis plate deserves a bit adjustment (=bending) and perhaps the axles should be greased too.

Ready to rock'n'roll. Next it will get the motor control circuit. To be continued.

Connection to 8x2 LCD display

Next step is to add a LCD screen. I ordered a cheap 8x2 screen mainly for debugging purposes, but perhaps it could be used for some user interface in next project. Biggest problem in the connection with strip board is that the Seeeduino (and others in Arduino family) have some of their connections in wrong alignment (non 2,54mm). After quite lot of head scratching I finally found out that the holes Seeeduino PWM-side actually have the correct alignment. One only needs to solder new headers next to existing ones. Some soldering is also needed to utilize the IO-pins from 22 onwards.
I created a shield from strip board and pins. This makes connecting to outer world possible with some Kynar wire and ribbon cable connectors. The LCD is connected to 46..53 (d0..d7), 43..45 (control), +5 and ground. V0 has a 10kOhm contrast trimmer between +5V and GND. After downloading a example application from seeeduino website the "Hello world" was released.
The example code had some intrusive changes (it replaces the HD44780 code) to the Wire-library any Arduino system uses. Perhaps one needs to integrate the code better and send it to upstream.

Seeeduino Mega impressions

The Seeeduino Mega is a really neat device. Within the dimension of 71mm*53mm there is a 8bit Atmel1280@16Mhz, equipped with whopping 8KB of RAM and 128KB of flash and 70 I/O pins. The programming is done at PC, using a C/C++ in a bit toy-like IDE. With the help of really simple IDE, and its example applications and system libraries, one can get the LED blinking in an matter of minutes.

On the first inspections I found that the board seems to be fixed with wire cutter at the factory. I assume that the board had some leads connecting at wrong places and they simple cut the joints open, but unfortunately made some scratches over lines too. This was a bit worrying, but closer look with magnifying class and a tests with multimeter revealed no trouble. For testing I used a simple application to turn on and off the PWM-IO-pins
one at time to make sure, that the connections work. Fortunately there is no need to send the device back to supplier, may the play continue.
See the next picture, leftovers of wire cutting at top, right and bottom.

Toyware

Hello world. Welcome to my notebook on the experiments in the world of electronics. One colleague of mine (thanks, Samu) recently introduced me to the world of Arduino. After some research the mailman delivered a shiny state of the art microcontroller, Seeeduino Mega. More of that later.