Compter en ascii de 0 à 100

merci beaucoup!

Petit code vite fait :

int transformer(const unsigned byte n)
{
    if (n<10)
        return 30+n;
    
    if (n<100)
        return 3000+100*(n/10)+transformer(n%10);
    
    return 300000+10000*(n/100)+transformer(n%100);
}

mais le probleme est que pour mon afficheur je ne peux que mettre 1 caractère en hexadécimal en 0x30 ou 0x31... il faut que je fasse d'abord une conversion en decimal de la valeur ascii ou meme directement un caractere voila mon prog et c'est l'instruction graphic_voltage:
#include <18f4580.h>
#device ADC=8
#include <GSGCdef.h>
#use delay(clock=4000000)
#use rs232(baud=9600, xmit=PIN_C6,rcv=PIN_C7)
unsigned char conv;
unsigned char volt;


//-------------------------------------------------------
void OLED_rectangle(unsigned char x1,unsigned char y1,unsigned char x2,unsigned char y2, unsigned int16 color)
{
putc(GSGC_RECTANGLE);
putc(x1);
putc(y1);
putc(x2);
putc(y2);
putc(color/256);
putc(color%256);
}
//-------------------------------------------------------
void OLED_GRAPHICVOLTAGE(unsigned char x,unsigned char y,,unsigned char font,unsigned int16 color,unsigned char width,unsigned char height, unsigned char string, unsigned char terminator)
{
putc(GSGC_STRINGGFX);
putc(x);
putc(y);
putc(font);
putc(color/256);
putc(color%256);
putc(width);
putc(height);
putc(string);
putc(terminator);
}
//--------------------------------------------------------


//--------------------------------------------------------

void main(void)
{
SET_TRIS_B(0b00000000);
SET_TRIS_A(0b00000001);


setup_adc_ports(AN0_ANALOG);
setup_adc(ADC_CLOCK_INTERNAL);
set_adc_channel(0);

putc(0x55);

delay_ms(500);
while(true)
{


conv=READ_ADC();



putc(0x45);
while(!ADC_done())
{
}


volt=conv*0.396;




delay_ms(100);

OLED_graphicvoltage(0x05,0x05,0x02,0x00FF,0x01,volt,0x00);
//OLED_STRINGTXT(0x01,0x01,0x02,0xF800,0x41,0x00);
delay_ms(10);

//OLED_RECTANGLE(0x00,0x24,volt,0x31,0xFF00);



delay_ms(100);

}
}