Encore bonjour à tous!
Désolé de relancer le sujet mais je me suis dit que je vais utiliser le même 
Donc maintenant mon chef de service veut que je puisse modifier la taille de la police de l'afficheur S1D13700.
Je regarde donc S1D13700.h que voici:
#ifndef S1D13700_h
#define S1D13700_h
#include "WProgram.h"
/*uncomment the line below if you need to use non-default pins
for your data lines */
#define S1D13700_CUSTOM_DATA_PINS
#define FIXED_DIR DDRD
#define FIXED_PORT PORTD
#define FIXED_PIN PIND
class S1D13700
{
public:
S1D13700(void);
void writeCommand(unsigned char command);
void writeData(unsigned char data);
unsigned char readData(void);
void initLCD(void);
void setData(unsigned char data);
void writeText(char * text);
void setPixel(unsigned int x,unsigned int y, unsigned char state);
void setCursorAddress(unsigned int address);
void textGoTo(unsigned char x, unsigned char y);
void graphicGoTo(unsigned int x, unsigned int y);
void clearText(void);
void clearGraphic(void);
void drawBox(int x0, int y0, int x1, int y1);
void drawCircle(int x0, int y0, int radius);
void drawLine(int x0, int y0, int x1, int y1);
struct pin_type {
unsigned char d0;
unsigned char d1;
unsigned char d2;
unsigned char d3;
unsigned char d4;
unsigned char d5;
unsigned char d6;
unsigned char d7;
unsigned char a0;
unsigned char wr;
unsigned char rd;
unsigned char cs;
unsigned char rst;
} pins;
private:
void hardReset(void);
};
#define READDELAY() asm("nop");asm("nop");asm("nop");asm("nop");asm("nop");asm("nop");asm("nop");asm("nop")
/*definitions for specific LCD settings as well as the
command codes for various function */
#define S1D13700_SYSTEM_SET 0x40
#define S1D13700_SLEEP_IN 0x53
#define S1D13700_DISP_OFF 0x58
#define S1D13700_DISP_ON 0x59
#define S1D13700_SCROLL 0x44
#define S1D13700_CSRFORM 0x5d
#define S1D13700_CGRAM_ADR 0x5c
#define S1D13700_CSRDIR_U 0x4e
#define S1D13700_CSRDIR_D 0x4f
#define S1D13700_CSRDIR_L 0x4d
#define S1D13700_CSRDIR_R 0x4c
#define S1D13700_HDOT_SCR 0x5a
#define S1D13700_OVLAY 0x5b
#define S1D13700_CSRW 0x46
#define S1D13700_CSRR 0x47
#define S1D13700_MWRITE 0x42
#define S1D13700_MREAD 0x43
#define S1D13700_SCR_WIDTH 319
#define S1D13700_M0 0
#define S1D13700_M1 0
#define S1D13700_M2 0
#define S1D13700_WS 0
#define S1D13700_IV 1
#define S1D13700_FX 7
#define S1D13700_FY 14
#define S1D13700_WF 1
#define S1D13700_CR 39
#define S1D13700_TCR 90
#define S1D13700_LF 239
#define S1D13700_APL 40
#define S1D13700_APH 0
#define S1D13700_LINES 30
#define S1D13700_SAD1L 0
#define S1D13700_SAD1H 0
#define S1D13700_SL1 0xEF
#define S1D13700_SAD2L 0xB0
#define S1D13700_SAD2H 0x04
#define S1D13700_SL2 0xEF
#define S1D13700_SAD3L 0
#define S1D13700_SAD3H 0
#define S1D13700_SAD4L 0
#define S1D13700_SAD4H 0
#define S1D13700_CRX 0x04
#define S1D13700_CRY 0x07
#define S1D13700_CM 0
#define S1D13700_MX0 0
#define S1D13700_MX1 0
#define S1D13700_DM1 0
#define S1D13700_DM2 0
#define S1D13700_OV 0
#define S1D13700_SAGL 0
#define S1D13700_SAGH 0x70
#define S1D13700_SCRD 0
#define S1D13700_FLASH 0x16
#define S1D13700_TEXTSIZE ((S1D13700_SAD2H << 8) + S1D13700_SAD2L)
#define S1D13700_GRAPHICSTART ((S1D13700_SAD2H << 8) + S1D13700_SAD2L)
#define S1D13700_GRAPHICSIZE ((S1D13700_SL2+1) * (S1D13700_SCR_WIDTH+1))>>3
#define S1D13700_MEM_END 10800
#define S1D13700_SYS_P1 0x10 | (S1D13700_IV << 5) | (S1D13700_WS << 3) | (S1D13700_M2 << 2) | (S1D13700_M1 << 1) | S1D13700_M0
#define S1D13700_SYS_P2 0x00 | (S1D13700_WF << 7) | S1D13700_FX
#define S1D13700_CSRF_P2 0x00 | (S1D13700_CM << 7) | S1D13700_CRY
#define S1D13700_OVLAY_P1 0x00 | (S1D13700_OV << 4) | (S1D13700_DM2 << 3) | (S1D13700_DM1 << 2) | (S1D13700_MX1 << 1) | S1D13700_MX0
#endif
avec la doc du S1D13700 que voilà: http://www.lcd-module.de/eng/pdf/zubehoer/s1d13700.pdf
J'ai donc trouvé Fx et Fy qui correspond au nombre de pixel en X et en Y mais je ne trouve pas MOD qui débloque le mod 16pixel(la taille la plus grande si j'ai bien compris).
Voilà peut être que si j'ai de la chance quelqu'un pourra m'aider sinon bah tant pis 
Merci d'avance.