Raspberry Pi!

Raspberry Pi pre-release board
 (Photo credit: jared_smith)

A bit of digression never hurts, I suspect that most Arduino enthusiasts will also be very interested in the RasPi project as well. Raspberry Pi is a very small 'real' computer destined for the educational market. However, the initial release of ten thousand, due tomorrow, is aimed at developers and people like us. The major attraction is the size, about the same as a credit card only thicker, and the price, currently set at about $35.00. The attraction to us will be the possibility of interfacing the little board to Arduino projects in such a way that the whole electronics unit is inside the robot or whatever. Imagine a number of individual servers running on Arduinos being managed by a RasPi with keyboard and mouse on a Bluetooth link. Or maybe a robot with all the articulation and protection automated but being steered by a master brain  called RasPi.

Just like Christmas.....

I got two major deliveries today,the Ginsing board arrived and I have been playing with it this evening, very nice. Also, I now have a photo bag studio, or whatever, thing. You erect it, stick whatever you want to photograph inside and it acts as a self contained studio for taking good quality photos. I shall be trying that out maybe tomorrow.

Is there a problem?

Image via Wikipedia

As I wrote in the previous post, I have had some difficulty with the LCD shield that I am testing at the moment. The shield itself is fine, very well made and works really well but.................... It seems that none of the sketches in the current libraries will even compile let alone upload to the Arduino. The older library sketch works really well but has no connection with the rewritten LCD library as far as I can see. In addition, there seem to be many variations on the basic shield and although many are listed with proven pin outs in the wonderful Arduino Shield List, my shield is not listed under the name I bought it as. I bought my shield from Vivid Stock of Hong Kong and they don't offer a demo script themselves. Many other Chinese vendors appear to sell the same shield but there is no guarantee that they are identical. Has anyone reading this bought one of these shields, particularly from Vivid Stock, and got it working on the latest software? If so, please post your sketch here so that we may all benefit from it.

Back on track

I was over the moon when the LCD shield arrived. The I discovered that there were several problems involved in using it. There are updated libraries for it but most of them won't run on the LCD if you don't know which pins are used for what. In addition, the older libraries only work with older versions of the software. So after some thought, I have set up the previous version of the software and I am using it to test the shield. I have to report that it's excellent!

A cautionary tale.

My two Arduino Nano V3 boards arrived this morning. As I always do, I tried to upload 'Blink' to them as a test. No chance, they may as well not have existed as far as the software was concerned. I was getting the, "avrdude: stk500_getsync(): not in sync: resp=0x00" error. I checked around the forums and got several differing solutions to what seems to be a very well known problem. It's not Nano specific by the way. I tried most of them until I saw a post from someone who had simply updated his drivers. As I am on the latest version of the software, I had thought to be on the latest drivers as well. It would appear not, however, as once run in from the self installer all was well and everything now works as expected. The Nanos are very small and I am expecting to have a lot of fun with them quite soon. In addition, this mornings post brought me a very useful shield with both push switches and a 16x2 display already fitted and ready to go. It's going to be used for testing purposes on the new yellow trundle in order to speed up the design and software development.

Colour change for test trundle!

I have reviewed my testing for code changes over the weekend and decided to move the servo tests to a previous chassis that's now nearly ten years old and very yellow. It's bigger and heavier but has a large, flat surface for mounting the electronics and can carry dry cells very easily. I will be providing pictures of the new (old) chassis soon. The power supplies and ultrasonic sensors have now arrived so I will be getting down to some serious coding for them very soon as well.
I have also set up a Google code site for the sketches. There will mainly be simple snips of tested code that I have written myself to test and demonstrate what I am working on. I will, however, put any larger sketches I write there as well because they will be both open source and tested to work. The site is listed under 'Links to Projects' on the right.

Making the Trundle go forward

This is the code so far developed, not very complex yet but I have managed to make two continuous servos run in opposite directions and, so, to 'trundle' along.


// Trundle 1
// by codfangler
// This code is in the public domain.

#include <Servo.h>
Servo myservol;   // create servol object to control left servo
Servo myservor;  // create servor object to control right servo
                             
int posl = 0;       // variable to store the servol position
int posr = 180;  // variable to store the servor position

void setup()
{
  myservol.attach(9);     // attaches the servol on pin 9 to the servol object
  myservor.attach(10);  // attaches the servor on pin 10 to the servor object
}

void loop()
{
  for(posl = 0; posl < 180; posl += 1)    // goes from 0 degrees to 180 degrees
  for(posr = 180; posr < 0; posr += 1)  // goes from 180 degrees to 0 degrees
                                                            // in steps of 1 degree
{                                
    myservol.write(posl);              // tell servol to go to position in variable 'posl'
    delay(15);                              // waits 15ms for the servo to reach the position
}
{  
    myservor.write(posr);              // tell servor to go to position in variable 'posr'
    delay(15);                               // waits 15ms for the servo to reach the position
}
}

As the acrylic tube arrived simply to check sizes

After cutting to size and adding slots for wire

Simpler wiring by using a motor shield with  two servo outputs

Thank heaven for little.....

Trundles.

Sometimes, it's just good to be right. I fitted all the parts together, ran a sketch and I have a working trundle.

It can't roll across the floor, as the tiny Nano boards haven't arrived as yet, but everything is working and fits perfectly. YES!
Photographs, constuction details and code will follow soon.

Testing the acrylics.............

The various small test pieces of plastic arrived this morning. First impressions are that they seem to be much more robust than anticipated.

Bumper bundle!

Image via Wikipedia

If you know the source of that title, you must be as old as me.

This mornings mail brought a motor shield, a voltmeter, a long shaft 10mm drill bit, two servo mounting templates and 20 74HC595 shift register chips. This should make life very interesting. The drill bit is for some precision holes on the Trundle and the shift registers will help me make a very simple visual display look really cool, anyone for Knight rider?

Behold, "The Trundle"!

Imagine a tube, 50mm diameter and 100mm long. A wheel on either end but not central, closer to the edge and driven by an adapted servo. The centre has a smaller, 10mm, tube embedded through it and the connecting wires exit through here. Initially, this will be a stand alone buggy that will steer and travel by the use of the wheels alone. This will require a weight in the bottom of the larger tube in order to keep it in the correct position relative to the wheels. Control will be, hopefully, by a Bluetooth system  and should be fairly simple to manage in this first incarnation. The trundle will then become a test bed for most of the basic scripting requirements.

If you look up Trundle on the web, you will find it is the name of a hill fort. My use of the name is based on the concept of a wheeled vehicle that 'trundles' along.

I plough a lone furrow..........sigh.

I really didn't want this blog to be all me so I recruited Ian to add his two penu'th to it. However, he has younger children than me and they interfere with his efforts on an almost daily basis. Rugby being the most obvious area of time consumption. Nonetheless, he has begun a project, at long last, and will shortly be writing up his experiences here.

My researches got a boost yesterday when I found my missing tiny servos and my electronic calliper. I have now worked out, in my head at least, how to build the trundle units.

The trundle is a small two wheeled buggy intended to be used on the end of a leg of the larger control unit. It will, however, have it's own 'brain' and have some self protecting capabilities.

Wither the Duemilanove?

Mine arrived yesterday and I checked it out when I got home. I was very impressed by the size and the fact that it ran my sketches straight out of the box. I know that it's obsolete now but you can still buy them for a very good price if you know where to look. I have also ordered a couple of Arduino Nano clones from China and, when they arrive, I should be in a position to set up some sort of network test as well. My biggest problem at the moment would seem to be the chaos caused by the Chinese New Year celebrations. I have quite a few items ordered and paid for - and sent as well - that have just not arrived yet. The suppliers are being very helpful and will re-send the goods if they haven't arrived by next week so I won't be out of pocket. I will, however have lost quite a lot of time on my project. Speaking of which, I have reached the point where I want to name it and have hit a stumbling block. My original name was, "Self Protecting Autonomous Machine" but that isn't really the impression I want to give so I have opened the name thing up to anyone who cares to make a sensible suggestion. I will publish the usable ones and, hopefully, use the best for the project. Simply post it as a comment below.