File content as of revision 0:3f43ed494764:

#include "mbed.h"
#include "font_5x7.h"

struct UART_buf
{ 
    uint8_t STA;
    uint8_t MODE; 
    uint8_t CMD;
    uint8_t LEN;
    uint8_t DATA[32];
    uint8_t END; 
};
 
// I2C address
int DoT_ADDR = 0x71<<1;

I2C Dotmatrix(I2C_SDA, I2C_SCL);

char Data_BUF[17] = {0, 0 ,0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};

Serial SerialUART(PA_2, PA_3);

UART_buf RX_BUF;

void SerialUARTRX_ISR(void);
void data_write(char *data, int len);
void Command_Write(uint8_t com);
void Dotmatrix_init(void);
void char_data_write(char data);

int main() {
    
    SerialUART.baud(115200);
    
    SerialUART.attach(&SerialUARTRX_ISR);
    
    Dotmatrix_init();
    
    while(1)
    {
    }
}

void SerialUARTRX_ISR(void)
{
    static uint8_t RX_count = 0, RX_Len = 32, RX_Status = 0;
    uint8_t rx_da = SerialUART.getc();
    switch(RX_Status)
    {
        case 0:
            if(rx_da == 0x76)
            {
                RX_BUF.STA = rx_da;
                RX_Status++;
            }
            break;
        case 1:
            RX_BUF.MODE = rx_da;
            RX_Status++;
            break;
        case 2:
            RX_BUF.CMD = rx_da;
            RX_Status++;
            break;
        case 3:
            RX_BUF.LEN = rx_da;
            RX_Len = RX_BUF.LEN;
            RX_Status++;
            if(RX_Len == 0)
                RX_Status++;
            break;
        case 4:
            RX_BUF.DATA[RX_count] = rx_da;
            RX_count++;
            if(RX_count == RX_Len)
            {
                RX_Status++;
                RX_count = 0;
                RX_Len = 32;
            }
            break;
        case 5:
            if(rx_da == 0x3E)
            {
                RX_BUF.END = rx_da;
                RX_Status = 0;
                switch(RX_BUF.MODE)
                {
                    case 0x01:
                        if(RX_BUF.CMD == 0x17)
                        {
                            char_data_write(RX_BUF.DATA[0]);
                        }
                        break;
                }
            }
            break;
    }
}

void data_write(char *data, int len)
{
    data[0] = 0;
    Dotmatrix.write(DoT_ADDR, data, len);
}

void Command_Write(char com)
{
    Dotmatrix.write(DoT_ADDR, &com, 1);
}

void Dotmatrix_init(void)
{
    // Internal System Clock enable
    Command_Write((char)0x21);
    // INT/ROW output pin Set -> ROW Driver output
    Command_Write((char)0xA0);
    // Dimming Set -> 15
    Command_Write((char)0xEF);
    // Blinking Set -> off
    // Display Set -> on
    Command_Write((char)0x81);
}

void char_data_write(char data)
{
    uint8_t read_c, i, j, c_buff[8] = {0, 0, 0, 0, 0, 0, 0, 0};
    for(i=0; i<5; i++)
    {
        read_c = font[data-0x20][i];
        if(read_c)
        {
            for(j=0; j<8; j++)
            {
                if(read_c & (0x80 >> j))
                {
                    c_buff[j] |= (0x01 << (i+1));
                }
            }
        }
    }
    for(i=0; i<8; i++)
        Data_BUF[i*2+1] = c_buff[i];

    data_write(Data_BUF, 17);
}