[51] ISP programmer issue

[praveenrpk92]

Hi, I'm trying to design an ISP programmer for AT89S52. I'm using 2 Microcontrollers, controller 1 has chip erase code in it & I have successfully erased controller 2. Although I'm not able to read the MISO pin which should give the value 01101001 during byte 4 cycle of programming enable sequence.

Here's the code in controller 1:

#include <REGX52.h>
#include <intrins.h>

sbit RST=P2^0;
sbit MOSI=P2^1;
sbit MISO=P2^2;
sbit SCK=P2^3;

unsigned char bit_i=0;
bit txbit,rxbit,flag;
unsigned char a,b,c,d;
unsigned int i=0;
unsigned char rx,tpx;
void delay_us(unsigned int d);
void send(unsigned char x);
void sendbyte(unsigned char spibyte);

void main(void)
{ 
delay_us(32000);
	MISO=1;
	RST=0;
	SCK=0;
	TMOD=0x20;
PCON=PCON | 0x80;
	TH1=0xFF;
	TL1=0xFF;
SCON=0x50;
	TR1=1;

	
	RI=0;
	TI=0;
	
  send('M');
	delay_us(1000);
	
	send('C');
	
	SCK=0;
	//RST=0;
	
	for(i=0;i<500;i++)
	{P1_3=1;delay_us(1000);P1_3=0;}

//=======Program enable===========
	a=0xac;
	b=0x53;
	c=0x00;
	d=0x11;
	sendbyte(a);
	sendbyte(b);
	sendbyte(c);
	sendbyte(d);

//==========Erase==================
	a=0xac;
	b=0x82;
	c=0x12;
	d=0x13;
	sendbyte(a);
	sendbyte(b);
	sendbyte(c);
	sendbyte(d);
	
	for(i=0;i<1000;i++)
	{P1_3=1;delay_us(1000);P1_3=0;}
 send('E');
	
	
	
		
while(1){
P1_3=1;

	for(i=0;i<2500;i++)
	{P1_3=1;delay_us(1000);P1_3=0;}

P1_3=0;
  }
}


void delay_us(unsigned int d)
{
   unsigned int i, limit;
   limit = d/15;

   for(i=0;i<limit;i++);
	
}

void send(unsigned char x)
{
SBUF=x;
while(TI==0);
	//delay_us(10000);
	TI=0;
}

void sendbyte(unsigned char spibyte)
{
   rx=0x00;
	if(spibyte==0x11){flag=1;}else{flag=0;}
	for(bit_i=0;bit_i<8;bit_i++)
	{P1_3=1;
		txbit=spibyte/128;
		spibyte=spibyte<<1;
		MOSI=txbit;
		delay_us(1000);
  	_nop_();
	  SCK=1;
	  delay_us(1000);
	  _nop_();
		if(flag)
		{tpx=MISO;send(tpx);
	 	rx= rx | (tpx<<(7-i));}   
		 SCK=0;
		 P1_3=0;}
	if(flag)
	{send(':');
	 send(rx);
	 send(';');}
}

Here's what received in hyperterminal:


I'm getting these weird smiley symbols. I tried to read the value of MISO pin in while loop and I'm getting 1's and 0's properly. Please help.

Update : I replaced send(tpx) with send(tpx+48) and got the 01101001 sequence in hyperterminal. So, rx should be 0x69 which should display 'i' in hyperterminal but I'm getting nothing for that send instruction alone.

 

[KlausST]

Hi,

I'm confused.
SPI is a synchronous serial interface. The timing is forced by the clock signal.
Hyperterminal is for UART style. UART has no clock signal. Timing is forced by the setup for a baud rate.

I can't find a baud rate setup in your code...

Please describe mor detailed.

Klaus