Hi,

I am struggling to get software access to the UART bootloader on T89C51CC01.

I have no trouble activating the bootloader by hardware (basically pull PSEN down and resetting), but what I want to do is send a command to my program (in user FM0) which will call the bootloader at 0xF800 in FM1.

Here's what I've got. foo is set when I see a certain escape sequence, and I know it works because the '*' is transmitted:


if (foo)
{

TI = 0;
SBUF = '*';
while (!TI)
;
EA=0;
FCON=0x00; /* Probably should be 0xF0 */
AUXR1 |= ENBOOT; /* Enable boot flash area */
_opc(0x02); /* LJMP 0xF800 */
_opc(0xF8);
_opc(0x00);
while(1) /* Should never come back */
;

}


All that happens is I get a * and the chip resets. What I want is to send the escape sequence then send 'U' and talk to the bootloader. It ought to be simple, but I don't get it.

Any help would be greatly appreciated.

Thanks,

Andy