Arduino unsigned long int to char*

Question

I am coding on Attiny85 with IRremote and SSD1306 libraries customized.

When receiving IR data the results are stored this way:

unsigned long                 value     // Decoded value, max 32 bits
volatile unsigned int         *rawbuf   // Raw interval in 50uS ticks
int                           rawlen    // Number of records in rawbuf

OLED display related functions are:

void printChar                (char ch)
void printString              (char* pText)

I am struggling with printing the received IR value to the OLED SSD1306 screen. User is able to review and save the received code to EEPROM and hence I have tried all different conversions but I am unable to print the results.value to the screen in a way that it would display the received HEX code (for example 0xE0E040BF which is Power on in Samsung television).

Due to lag of Serial in attiny85 I have no clue how I could debug this and get it working. Any help?

EDIT (adding relative code):

#include "SSD1306.h"
#include "IRremote.h"
...
if (irrecv.decode(&results)) {  
    dumpCode(&results);        
    irsend.sendRaw(buff, results.rawlen, 38);
    oled.printString("Received IR");
    // Print received hexadecimal IR code to the OLED screen
    irrecv.enableIRIn();    
    irrecv.resume();   
}

Answer 1

If I understand it correctly you just want to convert a unsigned long value into an hex string, you can use sprintf for this purpose ( ideone ):

const unsigned int BUFFER_LENGTH = 16;
char buffer[BUFFER_LENGTH];
unsigned long value = 0xE0E040BF;
sprintf(buffer, "0x%08X", value);
printf("%s\n", buffer); // printString(buffer)

so that you can pass buffer to the printString method of the oled screen.

The format specifier %08X instructs printf to format the value as an hexadecimal number, with capital letters always showing all 8 hex values for the 4 bytes and padding it with 0s.

Answer 2

You could do this:

int IR;
char hexadec_s[11];
sprintf(hexadec_s,"0x%08x",IR);
printString(hexadec_s);

I believe this should do the trick. Let me know if it worked.