File content as of revision 0:21b4d8237564:

#include "mbed.h"
#include "TextLCD.h"

struct UART_buf
{ 
    uint8_t STA;
    uint8_t MODE; 
    uint8_t CMD;
    uint8_t LEN;
    uint8_t DATA[32];
    uint8_t END; 
};
 
// rs, rw, e, d0-d3
TextLCD lcd(PB_12, PB_13, PB_14, PB_15, PA_9, PA_10, PA_11); 

Serial SerialUART(PA_2, PA_3);

UART_buf RX_BUF;

void SerialUARTRX_ISR(void);
void LCD_printf(uint8_t *data, uint8_t len);

int main() {
    
    uint8_t ab[3] = {1, 2, 3};
    SerialUART.baud(115200);
    
    SerialUART.attach(&SerialUARTRX_ISR);
    
    LCD_printf(ab, 3);
    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 == 0x18)
                        {
                            LCD_printf(&RX_BUF.DATA[0], RX_BUF.LEN);
                        }
                        break;
                }
            }
            break;
    }
}

void LCD_printf(uint8_t *data, uint8_t len)
{
    char buf[32];
    for(int i=0; i<32; i++)
    {
        if(i<len)
            buf[i] = data[i];
        else
            buf[i] = 0x20;
    }
    lcd.locate(0, 0);
    lcd.printf(buf);
}