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?

Hi Coder27,

I am reading up a bit on those arrays and I have a question for you if you don't mind?

Is it possible to use an array element in digitalWrite() like in the following example?

digitalWrite(myArray[2], HIGH);  or   digitalWrite(myArray[2], myArray[3]);

Or,... if a multi-dimensional array was used such as myArray[8][8] with, say, myArray[2] holding the pin number and the second dimension of the array [3] holding the HIGH or LOW, how would the syntax for that work?  I would think that the syntax would be incorrect to write it as

digitalWrite(myArray[2], [3]);

Don't know if my question is clear or not but,.... you might get the picture of what I am trying to do here.  I am looking at having separate arrays for seconds, minutes and hours.

Thanks,

John

John,

  Yes, you can use an array element in digitalWrite, either as the first

or second parameter (or both), essentially anywhere you might otherwise

use a simple number or variable or algebraic expression.

  As you seem to understand, you can either have more than one

single-dimensional array, sometimes called parallel arrays, or you

can have an array of structs, or an array of arrays.

> digitalWrite(myArray[2], [3]);

The "[3]" isn't right.  Each parameter to digitalWrite is treated separately,

so the "[3]" needs to have the name of the array variable in front of it,

like you have for myArray[2], except it would probably have a different array name,

because the second parameter of digitalWrite is the LOW/HIGH setting,

rather than the pin number.  Read up on arrays so you are clear how it works.

I think I am getting the idea of how to set up an array, or even a multi-dimensional array but I am struggling a bit with how to use it in the BCD clock.  If it was a matter of simply turning on or off one individual LED at a time I don't think I would have a problem but for displaying the seconds portion of the time, I am using 7 LEDs which will sometimes have  only one LED turned on while at other times it will have two and sometimes three LEDs turned on at the same time.

It works fine using the switch statement but I can't figure out how to do the same thing using an array.

The following is a portion of the code that I used in the switch statement showing the first 9 of the 60 seconds needed.

void loop(){

  seconds++;

  switch(seconds){

   case 1:

      digitalWrite(led1, HIGH);  //led1 ON

      delay(1000);

      break;

   case 2:

      digitalWrite(led2, HIGH);  //led2 ON

      digitalWrite(led1, LOW);  

      delay(1000);

      break;

   case 3:

     digitalWrite(led1, HIGH);  //led1 and led2 ON

     delay(1000);

     break;

   case 4:

     digitalWrite(led3, HIGH);  //led3 ON

     digitalWrite(led2, LOW);

     digitalWrite(led1, LOW);

     delay(1000);

     break;

   case 5:

     digitalWrite(led1, HIGH);  //led3 and led1 ON

     delay(1000);

     break;

   case 6:

     digitalWrite(led2, HIGH);  //led3 and led2 ON

     digitalWrite(led1, LOW);

     delay(1000);

     break;

   case 7:

     digitalWrite(led1, HIGH);  //led3, led2 and led1 ON

     delay(1000);

     break;

   case 8:

     digitalWrite(led4, HIGH);  //led4 ON

     digitalWrite(led3, LOW);

     digitalWrite(led2, LOW);

     digitalWrite(led1, LOW);

     delay(1000);

     break;

   case 9:

     digitalWrite(led1, HIGH);  //led4 and led1 ON

      delay(1000);

      break;

)

As you can see, with each increment of the seconds different pins are set HIGH and others are set LOW.  I can't seem to wrap my head around how to come up with a matrix that will do the same thing.  Any thoughts?

Thanks,

John

John

If you set up a single array (0-9) with the decimal number that matches the binary value of the leds you need to turn on. (ie 0 = none, while 127= all 7 leds)

At each second you could read the array element matching the second, and then turn on the leds.

You can use the port manipulation ( http://www.arduino.cc/en/Reference/PortManipulation ) to set multiple pins at once.

Decimal numbers also work, so direct reference to your array should work.

Does this make sense.??

Mark

Hi Mark,

As you can see, coding in 'C' and the Arduino are both new to me and I am in a learning process.  Coder27 suggested using arrays rather than the switch statement and that makes sense since the code for a 24 hour clock could get quite large and more difficult to read with the switch statement.  I looked at a couple of short tutorials on arrays and I think I get the general idea.

Your suggestion certaiinly makes sense and is something that I would never have thought of. I will follow your link and read up on the port manipulation to see if I can get an understanding of how that works as well.

Thank you very much for your help.  It is very much appreciated.

Have a very Merry Christmas and all the best in the 2013.

John

Hi Mark,

I have been looking at some info on the manipulation of the ports on the Arduino.  I don't have it all down pat yet but I am getting a better understanding of how it works. One thing that I am unsure of is whether I can use a variable in the port designation.  Since I will likely be using pins 1 to 13.

Pins 1 to 7 is on PORTD and pins 8 to 13 is on PORTB,  so could I use a variable such as PORTx or PORTy?

For example:

char x='B'

char y='D'

for( int i=1; i< 13; i++ ) {

    if( i < 8) {

       PORTx = pinArray[3];   // PORTD     

     }

}

else {

     PORTy = pinArray[9];    // PORTB

    }

}

I am practicing with the UNO but once I get to the point where I can get things working properly I will start using the Mega because it has more pins and of course more memory.

Thanks

John

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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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.

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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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..

Hi John.  Is it safe to say the you are also finding the learning curve a little steeper due to the choice to transition from the analog world into the digital world.  Did you do any digital modes with the HAM equipment?

At your service.

Yes, digital is quite different than analog but I am doing a lot of reading, testing, and of course, asking questions on this forum.  As I mentioned in a previous post, it is great to see that there are so many people who are both willing, and have the patience to help those who are new to Arduino and the 'C' language such as myself.

I did very little in terms of digital with my ham exams.  Most of it is basic electronics, antenna theory, IC circuits, filters etc.

My main hobby is designing and building antennas. My wife says I have so many antennas up that people will think we are terrorists or something.     She just doesn't understand Amateur Radio.  When she asks me why I like ham radio and I say I enjoy talking to people around the world, she says:  "Why don't you just use the telephone?"

I have been reading up on this "Charleplexing" and I am finding that controlling 20 LEDs to sometimes have a single LED on and sometimes multiple LEDs on is quite complicated.  Not sure that I am getting my head wrapped around this at all.

John

Billabott

Thanks for your kindness re NZ.

Yes living just out of Chch,  we are all proably world experts in earthquakes/aftershocks after 13,000 of them.

You are quite correct about electron flow, and I do realise that about electron flow (learnt that wayyyyy back during training).

I thought  that John might not, and asummed he was a beginner (mistakely....sorry and apologies) (and yes the extra e was a typo ..sorry).

For those struggling to comprehend electricity, electon flow isn't something that helps....

John

Years ago I did some multiple output work using latches, and I wonder if adding some latches for your hour and minute leds might not reduce your pin count.

There are also some I2C devices that might also reduce your pin count, and make the code a little easier for the leds that don't need to change often.

Mark

Hi Mark,

Actually I never really thought about latches or flip-flops, (almost the same thing) or 12C devices.  I was really trying to find a way of doing it with a standard UNO.  As I mentioned before, I could use the Mega if I can find some PORT to Pin information. I could just test for them I guess but thought it would be far less time if I was able to find it on the internet.  I know PORTD controls pins 0-7 and PORTB handles pins 8-13 but I can't find anything like that for the Mega2560.  I think I will try a few more things with the bare UNO and if I can't come up with any ideas I'll look at maybe using a 12C device or perhaps latches.

Appreciate the suggestions Mark.

John