Error in sketch code

Hi JohnC.  Good attempt.  In respect to the current limits of each I/O pin,  I would suggest the need to multiplex the LEDs (only one on at a time.)  As a more correct example:

void setup(){

ledMode(led1, OUTPUT);

ledMode(led2, INPUT);   // look up about writing a 1 to the input pin to put it in high impedance mode.

ledMode(led3, INPUT);

ledMode(led4, INPUT);   // it was stated that pinMode is preferred;  I don't know

ledMode(led5, INPUT);   // and don't want to look it up right now.  sorry. 

ledMode(led6, INPUT);

ledMode(led7, OUTPUT);   //  this is the source of one of your errors  led7,

}

void loop(){

seconds++;

while(1){

   if (seconds == 1){

      digitalWrite(led1, HIGH);

      digitalWrite(led7, LOW);

      delay(10);

      digitalWrite(led7, HIGH);    //  in theory this will probably work

                                                 // use at your own risk since it is being adapted from PIC techniques

      delay(10);

      }  // fi     * really?  I am the first to note/share this technique

         //                  of marking what this closing brace matches  !?!

...

if (timeToUpdateDisplay) break;

}  // elihw     * ditto

}  // pool       * ICNBI

Thanks billabott,

When it comes to the actual BCD clock code it will have to have more than 1 led on at a time so I'm not sure how that would work with multiplexing. 

You say that ledMode(led7, OUTPUT); is the problem but I don't see what the problem is?  It is writen the same as all of the other ledMode statements.

Should I be using pinMode() rather than ledMode()?

I was also wondering if it would be better to use the switch statement rather than multiple if statements?

Ok, I tried to use a variable for the PORTD and PORTB and that won't work but I figured out another way to achieve what I needed.

I re-wrote the code, eliminating the switch statement, and used  PORTD and PORTB which is controlled by the secsArray[], the minsArray[], and the hrsArray[].  I ran it using the Arduino Simulator and it is working fine so far.  I only have it coded to where it counts the seconds and minutes so I have to work on the hours now. If I can get that working properly in the simulator, I will upload it to the UNO and see how it runs there.  Using the arrays and the PORTS sure shortens up the code a lot.

It has been quite a learning experience but I'm getting a handle on this 'Arduino C' coding now.

Thanks to Coder27, billabott, and Mark Beckett.  You guys are great!

John

John

I was in the same boat as you just 12 months ago. No experience with c/c++, and its been a steep but enjoyable experience.

Can I suggest you try picking up The Arduino Cookbook (by Michael Margolis) 2nd edition. It is well layed out and full of useful advise and solutions.

You can manipulate some parts of the port using suggestions here ( http://www.arduino.cc/en/Reference/PortManipulation )

It has a link to The Bitmath Tutorial and note that you can read the port as well.

Re memory, the 328 has 30k of code space but only 2048 bytes of ram. Libraries can consume a lot, and you can help yourself by looking inside the library to see what variables they use, and pass the data using the same variable.

My last project I had to remove all the library parts I didn't need, as I ran out of ram.....

You should also reduce the variable to the maximum size you need ie if you only have a number 0-255, then a byte variable saves ram.

Also if you have a lot of serial.print("this is text blah  ")  statements you can save ram by off loading them using this :- (Can't recall where I found it ...sorry to the original author)

#include <avr/pgmspace.h>  // allows storing strings in Flash memory

void showString (PGM_P s)

{

   char c;

    while ((c = pgm_read_byte(s++)) != 0)

       Serial.print(c);

}

then in your code...

showString(PSTR("print this text\n"));    // the \n is a CR/LF

You might not need the Mega after all.

Cheers

Mark

Thanks Mark,

Interesting concept.  I think I will probably use the Mega anyway.  For my BCD clock project I need to control 20 LEDs and the Mega has 54 pins that can be used. I looked at maybe multi-plexing the UNO but to be honest, I haven't been able to figure out how to do it with 20 LEDs where 2 or more may be required to be turned on or off at once. I'm not really all that knowledgable about multi-plexing with the Arduino.

I have to locate some info on the Mega's ports though.  On the UNO,  PORTD controls pins 1 - 7 and PORTB controls pins 8 - 13 however, I have not been able to find any info on which ports are on the Mega and which pins that they control. 

Given that I only started learning the Arduino and 'Arduino C' two weeks ago, I feel that I have made reasonable progress but I still have a long way to go. The help that is available from users here in this forum certainly makes the learning process a lot easier.

I just happened to stumbled upon that Arduino Simulator and I found it to be quite helpful for testing my code. 

John

I'll bet if you try to translate this PIC C code into 'Duino C you will learn a lot; you can even do it in the Simulator.  (Oh, oh, the source code I wrote for the hpLED chaser display in the video was over written. Sorry)  This one works in a similar fashion:

Example: If you were to try this using only 3 digital i/o pins, each pin has a current limiting Resistor whose value is R/2.  A good number for R is 10K, therefore R/2 = 5K.  Attached to the R/2s there are hetero-paired LEDs (1 anode and 1 cathode on each node) for a total of 6 LEDs.  The first hpLED is connected to R1-R2, the second hpLED is connected to R1-R3, and the third hpLED is connected to R2-R3.  Initialize by setting all 3 pins to INPUT (high impedance /.: not enough current flows to light up any LED).  We can select any two pins and make them OUTPUTs hence when one pin  is sourcing current (0 or LOW) and the other pin is sinking current (1 or HIGH) the direct conversion of electrical energy to a photonic emission will occur (... that means the LED will light UP).   Question: If P1 is High and P2 is Low; which P(out) should we toggle to make the LED blink and at what speed? Answer: Either one (it doesn't matter) and slower that 48 Hz.

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RE: Error in sketch code

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In this video you can see a PICKIT1 Flash Starter Kit running the code I wrote for hpLED_chaser.   If the wait loop time(s) were very much shorter, all the LEDs would appear to be ON simultaneously; and that, my friends, is Persistance Of Vision at work.  Check out some of these POV videos on YouTube.

It is great that you are trying to get a better understanding of how to apply these concepts.  For more details please see:  http://en.wikipedia.org/wiki/Charlieplexing

Warning: Hetero pairing leads to photonic emissions.

Thanks billabott,

I will look at the code and the videos as well.

John

Hi, John.

That's right you cannot reverse potential on a node connected to ground.  Ground is a source of electrons that flow to nodes with a positive potential.  The thing to think about is the an output pin that is set to 1 or High is more positive than an output pin that is set to 0 or Low.  The current will flow between those pins if a path exists.  Any output pin can be set to High or Low under the control of the software.  Whatever path for current flow that exists will activate. 

P.S.  I have found a great book for you to learn C++ with: Simple C++: Featuring Robodog and the Profound Object-Oriented Programming Method 

Oh, heck, Jose Pino has taken almost all the fun out of this project by documenting his PIC design at http://www.josepino.com/?anp-1224hr-led-clock1.

John

Don't go to the dark side and borow someone elses work, stick with yours.

You will learn a lot more.

Keep your sketchs that you create along the way, they will serve you later.

Billabot

billabott wrote:

when one pin  is sourcing current (0 or LOW) and the other pin is sinking current (1 or HIGH)

 

I always find begineers get confused over true current flow.

I found that using terms such as "..the HIGH causes current to flow to the LOW..", which is not right but helps when they use the water comparison.

I recall a NZ comedian (Fred Dagg) once describing the wind along the lines of "... the big Highs rush around trying to fill the Lows and make them all even....."

Cheers

mark

Really?  I tried to be careful not start the silly waste of  keystrokes about which way current flows.  So you are saying the surplus electrons and the excess holes meet in the middle somewhere and cancel each other out?     No?  You said, "I always find begineers get confused over true current flow."  I am not sure what you are saying exactly.  No matter.  Aal izz well.  No worries, mate. 

I know that the convention by historical error ( and 100 years later, they didn't want to correct the mistake when it was better understood ) is for "Current" to "Flow" from positive to negative, but, that is not what is really happening is it?  

I declare myself to be a life long learner.  I am neither a begineer or a beginner.  Thank you.  I love New Zealand, except for the earthquakes and I thank all the people there for helping to make films such as The Lord of the Rings Trilogy and The Hobbit Trilogy.

We must accept Atmel as the Authority on the issue in this case.  In the pertinent document(1) it states:

Port D is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit).  The Port D output buffers have symmetrical drive characteristics with both high sink and source capability.  As inputs, Port D pins that are externally pulled low will source current if the pull-up resistors are activated.

That clearly says that something, presumably holes because it cannot be electrons in my opinion, flows into the low/0/ground.  So Atmel adheres to the conventional view of current flow.  That's fine.   It's just not the way my brain understands the truth of electron flow. 

The only visualization of conventional current flow I can think of is a film of a freshly opened 3 liter bottle of 7Up being played in reverse - then you can actually see the holes(bubbles) being filled up with electrons and disappearing from existance.  Silly, isn't it.

(1) http://www.atmel.com/Images/8271S.pdf

Thanks billabott,

I am aware that electrons flow from negative to positive, (had to do some electronic stuff to get my ham radio license), but I wasn't thinking in terms of positive and negative when thinking about a pin being HIGH (positive), and a pin being LOW (less positive).  I generally think of negative as being ground as opposed to being "less positive". Since the Arduino has ground pins, that's what I was thinking was being used and could not understand how you could reverse that pin to be positive.

As for books, as I mentioned prviously, I bought that book that you recommended by Simon Monk.  While it was helpful I found it to be lacking in a number of areas as far as learning 'C' goes.  I have since ordered another book called Beginning Arduino Programming. I am expecting it to arrive shortly.

Thanks again.

Thanks Mark,

I have some knowledge about electronics but little about the Arduino and the 'C' programming language although I think I am getting a bit of a handle on the 'C' now.  I keep all my code snippets to review periodically and also in the event that I can use them in future projects. The BCD clock that I am working on uses 20 LEDs that I am controlling with Port manipulation however, the UNO does not have enough pins so I am trying to figure out how this multiplexing, or Charlieplexing works to reduce the number of pins required

Thanks..

Thanks Mark,

I have some knowledge about electronics but little about the Arduino and the 'C' programming language although I think I am getting a bit of a handle on the 'C' now.  I keep all my code snippets to review periodically and also in the event that I can use them in future projects. The BCD clock that I am working on uses 20 LEDs that I am controlling with Port manipulation however, the UNO does not have enough pins so I am trying to figure out how this multiplexing, or Charlieplexing works to reduce the number of pins required

Thanks..