Of course, I have a memory corruption, but I'm not able to fix it...

[BERTRAND Joël]

        Hello,

        I'm writting a CLRC632 driver for an ATmega1284. For a while, trace
were sent to a VFD screen but there is a lot of information and this
screen is too little to be usable.

        Thus, I have configured a serial port with RTS/CTS lines with
avr-usart-lib . My config contains :

#define RX_STDIO_GETCHAR_ECHO
#define RX_NEWLINE_MODE 2
#define USART_PUTHEX_IN_UPPERCASE
#define USART_EXTEND_RX_BUFFER
#define USART_SREG_SAVE_REG_NAME G_sreg_save
#define USART_SREG_SAVE_REG_NUM "r4"
#define USART_Z_SAVE_REG_NAME G_z_save
#define USART_Z_SAVE_REG_NUM "r2"
#define RX_BUFFER_SIZE 32
#define TX_BUFFER_SIZE 32
#define NO_USART1 // disable usage of uart1
#define NO_USART2 // disable usage of uart2
#define NO_USART3 // disable usage of uart3
#define CTS0_DDR DDRD
#define CTS0_PORT PORTD
#define CTS0_PIN PIND
#define CTS0_IONUM 2 // pin number
#define RTS0_DDR DDRD
#define RTS0_PORT PORTD
#define RTS0_PIN PIND

        Other lines of config header have not been modified. My collision
detection doesn't run as expected, thus I have added some debug trace.

        For example :

...
    acf.sel_code = ISO14443A_AC_SEL_CODE_CL1;

    (*tag).state = ISO14443A_STATE_ANTICOL_RUNNING;
    (*tag).level = ISO14443A_LEVEL_CL1;

unsigned char           t[3];

snprintf(t, 3, "%d", (*tag).level);
stty_print(t); stty_print(" (0)\r\n");
snprintf(t, 3, "%d", (*tag).level);
stty_print(t); stty_print(" (0.0)\r\n");
cascade:
    rx_len = sizeof(sak);
snprintf(t, 3, "%d", (*tag).level);
stty_print(t); stty_print(" (0.1)\r\n");
    iso14443a_code_nvb_bits(&(acf.nvb), 16);

snprintf(t, 3, "%d", (*tag).level);
stty_print(t); stty_print(" (0.2)\r\n");
snprintf(t, 3, "%d", (*tag).level);
stty_print(t); stty_print(" (0.3)\r\n");
    stty_print("Anticol ACF\r\n");
...

        When this program is executed, I obtain in serial line:

Booting firmware 2021052014
SPI initialized
CLRC632 initialization
CLRC632 reset done
CLRC632 wait for ready
CLRC632 ready
CLRC632 wait for ready
CLRC632 ready
CLRC632 initialized
Anticol REQA/WUPA
Anticol REQA/WUPA
Anticol REQA/WUPA
1 (0)
15 (0.0) <- why 15 and not 1 ?
15 (0.1)
15 (0.2)
15 (0.3)
Anticol ACF
Anticol SAK
SAK=08
15 (2)
10
Anticol REQA/WUPA
Anticol REQA/WUPA
Anticol REQA/WUPA
Anticol REQA/WUPA
Anticol REQA/WUPA
Anticol REQA/WUPA
Anticol REQA/WUPA
Anticol REQA/WUPA
1 (0)
15 (0.0)
15 (0.1)
15 (0.2)
15 (0.3)
Anticol ACF
Anticol SAK
SAK=08
15 (2)
10
Anticol REQA/WUPA

        stty_print() is a trivial function :

void
stty_print(unsigned char *t)
{
        while((*t) != 0)
        {
                uart_putc(*t);
                t++;
        }

        return;
}

        If I remove one snprintf() :

snprintf(t, 3, "%d", (*tag).level);
stty_print(t); stty_print(" (0)\r\n");
stty_print(t); stty_print(" (0.0)\r\n");
cascade:
    rx_len = sizeof(sak);
snprintf(t, 3, "%d", (*tag).level);
stty_print(t); stty_print(" (0.1)\r\n");
    iso14443a_code_nvb_bits(&(acf.nvb), 16);

I obtain :

1 (0)
1 (0.0)
19 (0.1)
19 (0.2)
19 (0.3)

        Now my question. Why tag->level value is modified by snprintf() ? There
is no concurrent thread.

        Information or help will be welcome.

        Best regards,

        JB