Arduino: cannot get value from array of struct

Question

I have a bidimensional array of struct that I defined and I want to get a value in a struct which itself is contained in an array.

I have tried to do the same kind of code in bare C and it seems to work while or Arudino IDE it doesn't (code isn't the exact same but it's generally the same thing).

Look at the example below, I am printing an arbitrary value taken out of my array of struct over serial and the only input I get on the Serial Monitor is a suit of 'ÿ' which from what I've seen on the internet means that the serial buffer is empty.

Does anything look wrong to you within the code below? (look at the end to see the relevant code)

/*
 * Metro - Station finder
 * Copyright © 2013, Adrien Tétar. All Rights Reserved.
 */

#include <Wire.h>

typedef struct {
  char nom[17]; // wanted number +1 for terminaison
  byte cor1[2]; // correspondance
  byte cor2[2];
  byte cor3[2];
  byte cor4[2];
  byte i2c;
  byte led;
} Station;

Station lignes[14][15] = {{
  {"Champs Elysees", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100001, B11101111},
  {"Concorde", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100001, B10111111},
  {"Tuileries", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100110, B11101111},
  {"Palais Royal", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100110, B10111111},
  {"Louvre Rivoli", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100010, B11101111},
  {"Chatelet", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100100, B10111111},
  {"Hotel de Ville", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100100, B11101111},
  {"St-Paul", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B11011111},
  {"Bastille", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B11110111},
  {"Ledru-Rollin", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B11110111},
  {"Faidherbe", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B11111011}
},
{
},
{
  {"Saint-Lazare", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100001, B11111110},
  {"Havre Caumartin", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100110, B11111110},
  {"Opera", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100010, B11110111},
  {"Quatre Septembre", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100010, B11111101},
  {"Bourse", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100110, B11011111},
  {"Sentier", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100100, B11110111},
  {"R. Sebastopol", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100100, B11111101},
  {"Arts et Metiers", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100100, B01111111},
  {"Temple", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100000, B10111111},
  {"Republique", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100000, B11110111}
},
{
  {"S. Saint-Denis", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100000, B11011111},
  {"R. Sebastopol", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100100, B11111101},
  {"Etienne Marcel", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100100, B11111011},
  {"Les Halles", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100010, B10111111},
  {"Chatelet", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100100, B10111111},
  {"Cite", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100110, B01111111},
  {"St-Michel", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B11111110},
  {"Odeon", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B11111101},
  {"St-Germain", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100101, B10111111},
  {"Saint-Sulpice", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B10111111},
  {"St-Placide", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B01111111},
  {"Montparnasse", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B11101111},
  {"Vavin", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B01111111},
  {"Raspail", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B11111011},
  {"Denfert", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B11101111}
},
{
  {"J. Bonsergent", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100000, B11111011},
  {"Republique", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100000, B11110111},
  {"Oberkampf", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100000, B01111111},
  {"Richard Lenoir", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B11111110},
  {"Breguet Sabin", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B11111101},
  {"Bastille", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B11110111},
  {"Quai de la Rapee", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B11111101},
  {"Gare Austerlitz", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B11101111},
  {"Saint Marcel", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B10111111},
  {"Campo Formio", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B11011111},
},
{
  {"Pasteur", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B11011111},
  {"Montparnasse", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B11101111},
  {"Edgar Quinet", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B10111111},
  {"Raspail", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B11111011},
  {"Denfert", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B11101111}
},
{
  {"Le Peletier", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100110, B11110111},
  {"La Fayette", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100110, B11111011},
  {"Opera", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100010, B11110111},
  {"Pyramides", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100001, B01111111},
  {"Palais Royal", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100110, B10111111},
  {"Pont Neuf", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100010, B11011111},
  {"Chatelet", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100100, B10111111},
  {"Pont Marie", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B11111101},
  {"Sully Morland", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B11111110},
  {"Jussieu", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B11111011},
  {"Place Monge", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B11110111},
  {"C. Daubenton", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B11111011},
  {"Les Gobelins", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B10111111},
},
{
  {"Invalides", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100101, B11110111},
  {"Concorde", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100001, B10111111},
  {"Madeleine", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100001, B11011111},
  {"Opera", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100010, B11110111},
  {"Richelieu Drouot", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100110, B11111101},
  {"Gds Boulevards", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100010, B11111011},
  {"Bonne Nouvelle", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100100, B11111110},
  {"S. Saint-Denis", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100000, B11011111},
  {"Republique", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100000, B11110111},
  {"F. du Calvaire", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100000, B11101111},
  {"St-S. Froissart", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100010, B01111111},
  {"Chemin Vert", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B01111111},
  {"Bastille", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B11110111},
  {"Ledru Rollin", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B11110111},
  {"Faidherbe", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B11111011}
},
{
  {"Saint Philippe", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100001, B11110111},
  {"Miromesnil", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100001, B11111011},
  {"Saint-Augustin", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100001, B11111101},
  {"Havre Caumartin", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100110, B11111110},
  {"La Fayette", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100110, B11111011},
  {"Richelieu Drouot", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100110, B11111101},
  {"Gds Boulevards", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100010, B11111011},
  {"Bonne Nouvelle", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100100, B11111110},
  {"S. Saint-Denis", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100000, B11011111},
  {"Republique", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100000, B11110111},
  {"Oberkampf", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100000, B01111111}
},
{
  {"Duroc", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B11110111},
  {"Vanneau", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B01111111},
  {"Sevres Babylone", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B11111011},
  {"Mabillon", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100101, B01111111},
  {"Odeon", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B11111101},
  {"La Sorbonne", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B11111101},
  {"Maubert", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B11011111},
  {"Cardinal Lemoine", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B01111111},
  {"Jussieu", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B11111011},
  {"Gare Austerlitz", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B11101111}
},
{
  {"Chatelet", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100100, B10111111},
  {"Hotel de Ville", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100100, B11101111},
  {"Rambuteau", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100100, B11011111},
  {"Arts et Metiers", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100100, B01111111},
  {"Republique", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100000, B11110111},
  {"Goncourt", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100000, B11111101},
  {"Belleville", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100000, B11111110}
},
{
  {"Saint-Lazare", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100001, B11111110},
  {"Madeleine", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100001, B11011111},
  {"Concorde", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100001, B10111111},
  {"Assemblee", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100101, B11111011},
  {"Solferino", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100101, B11111110},
  {"Rue du Bac", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100101, B11101111},
  {"Sevres Babylone", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B11111011},
  {"Rennes", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B11101111},
  {"N-D. Des-Champs", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B11011111},
  {"Montparnasse", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B11101111},
  {"Falguiere", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B10111111},
  {"Pasteur", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B11011111},
  {"Volontaires", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B11101111}
},
{
  {"Saint-Lazare", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100001, B11111110},
  {"Miromesnil", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100001, B11111011},
  {"Champs Elysees", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100001, B11101111},
  {"Invalides", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100101, B11110111},
  {"Varenne", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100101, B11111101},
  {"St-Fr. Xavier", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100101, B11011111},
  {"Duroc", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B11110111},
  {"Montparnasse", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B11101111},
  {"Gaite", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B11111110}
},
{
  {"Saint-Lazare", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100001, B11111110},
  {"Madeleine", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100001, B11011111},
  {"Pyramides", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100001, B01111111},
  {"Chatelet", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0100100, B10111111},
  {"Gare de Lyon", {0, 0}, {0, 0}, {0, 0}, {0, 0}, B0111000, B11110111}
}};


void setup() {
//  Wire.begin();
  Serial.begin(9600);
}

void loop(){
//  for (int j=0; j<16; j++) {
  byte a = lignes[0][0].i2c;
  Serial.write(a);
/*  for (int i=0; i<14; i++) {
    Serial.print(lignes[0][i].i2c, BIN);
    Serial.print(lignes[0][i].led, BIN);
    Serial.println(" ");

/*    Wire.beginTransmission(lignes[0][i].i2c); // PCF8574P GGG
    Wire.write(lignes[0][i].led);
    Wire.endTransmission();
    delay(10);*/
//  }
// }
}

Thanks a lot in advance for your help, I already spent a lot of time on this...

What language is this? Serial.write(a); doesn't look like c to me. Anyway, have you validated your serial connection works by just doing a basic Serial.write("Hello world");? — Brandon Yates, May 12 '13 at 22:02
ÿ is all 8 bits set to 1, 255 or -1 depending on the interpretation/sign. — Peter Mortensen, May 12 '13 at 22:47
If all your names are going to be compile-time constants, you should switch the char nom[17] field to a const char *nom. — unwind, May 13 '13 at 14:34
@BrandonYates It's Arduino, and yeah the Hello World kind of thing works well, it's just that one — user2037879, May 13 '13 at 17:02

Peter Mortensen · Answer 1 · 2013-05-12 22:46:25Z

up vote 2 down vote

In your given example, you are writing "lignes[0][0].i2c" which is B0100001. That is an ASCII code for space. Try validating your serial conection with a simple

Serial.Write("Hello World");

If that passes then try printing an actual string, for example,

Serial.Write(&lignes[0][0].nom)

edited May 12 '13 at 22:46

Peter Mortensen
7,51785385

answered May 12 '13 at 22:08

Brandon Yates
700616

Apparently, Arduino doesn't like to point to a struct element contained in an array... maybe compiler problem. – user2037879 May 13 '13 at 17:05

add a comment |

user2037879 · Accepted Answer · 2013-05-19 16:27:47Z

Apparently, it was caused by a memory overflow (thanks to Arduino IDE for NOT pointing that).

The Arduino IDE says 36kB available but that's Flash memory, one has to account SRAM.

This is worked-around by using PROGMEM.

cf. http://arduino.cc/en/Tutorial/Memory http://www.arduino.cc/en/Reference/PROGMEM

Also be careful, you have to use special functions for extracting and using value stored with PROGMEM.

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