/*
*
* doug_at.c
*
* usage: sdcc -mmcs51 doug_at.c
*
* Getting FLIP to work is troublesome.
* 
* The chip needs 5V, a 5V power pack into the powerjack is not good enough.
* 
* Use a USB serial lead connected to the RS232 headers with MAX232 chip removed and socket strapped.
* 
* To put chip into boot mode, use this sequence.
*
* turn USB off, press reset and PSEN and release reset when PSEN, then turn on USB switch.
* 
* use lsusb to check.
* 
* It is important to use sudo, othewise dfu-programmer reports device not present. 
* 
rem
rem compile doug_at.c and uses dfu-programmer to program the chip.
rem https://sourceforge.net/projects/dfu-programmer/
rem

sdcc -mmcs51 --std-c99  doug_at.c

lsusb

sudo dfu-programmer at89c5131 get
sudo dfu-programmer at89c5131 erase
sudo dfu-programmer at89c5131 flash doug_at.ihx
sudo dfu-programmer at89c5131 launch



* http://www.futurlec.com/USBDevBoard.shtml
*
* at89_UART_doc4346.pdf
*
* remove rs232 chip
* 
* strap
*  
* . u .
* .   .
* .   .
* .   .
* .   .
* .   .
* .---.   - strap
* .---.   - strap
*
*  . . . .
*  R G W B
* 
* connect ttl serial lead to header : red, green, white, black
*
* My PL2303HX TTL leads do not work with windows 10 but with LINUX
*
* https://github.com/dfu-programmer/dfu-programmer
*
*/
/*
==========================
SEC 1.0 Includes
==========================
*/
#include <AT89C513xA.h>
#include <stdio.h>


/*
==========================
SEC 2.0 Globals
==========================
*/

/* globals used in interrupts */
 volatile int intFlag;
 volatile char intCounter;
 volatile char uart_data;

 
/*
==========================
SEC 3.0 Interupt routines
==========================
*/
 
/*
The Interrupts defines in the include are one out and start at 0.
*/
/* Interrupts 
#define INT_RESET         0       // Reset
#define INT_EXT0          1       // External Interrupt 0
#define INT_TIMER0        2       // Timer0 Overflow
#define INT_EXT1          3       // External Interrupt 1
#define INT_TIMER1        4       // Timer1 Overflow
#define INT_UART0         5       // Serial Port 0
#define INT_TIMER2        6       // Timer2 Overflow
#define INT_PCA           7       // Programmable Counter Array
#define INT_KEYBOARD      8       // Keyboard on P1
#define INT_TWI           9       // Two Wire Interface
#define INT_SPI           10      // Serial Peripheral Interface
//                        11         Reserved
//                        12         Reserved
//                        13         Reserved
#define INT_USB           14      // USB events
//                        15         Reserved

*/

//INTERRUPT(int0_IT, 0 )
void int0_IT(void) __interrupt 0
{ 	
	//SBUF = uart_data;  
    intCounter += 10;
	intFlag = 1;
}

//INTERRUPT(intTmr0_IT, 1 )
void intTmr0_IT(void) __interrupt 1 	
{ 	
	SBUF = uart_data;  
    intCounter +=2;
}

//INTERRUPT(intExt1_IT, 2 )
void intExt1_IT(void) __interrupt 2
{ 	
	SBUF = uart_data;  
    intCounter +=3;
}

//INTERRUPT(intTmr1_IT, 3 )

void intTmr1_IT(void) __interrupt 3
{ 	
	SBUF = uart_data;  
    intCounter +=4;
}


void serial_IT(void) __interrupt 4 
//INTERRUPT( serial_IT , 4 )
{
	//char uart_data;
	//intFlag = 1;
	if (RI == 1) 
	{                    /* if reception occur */
		RI = 0;            /* clear reception flag for next reception */
		uart_data = SBUF;  /* Read receive data */
		SBUF = uart_data;  /* Send back same data on uart*/
		intCounter ++;
	}
//else TI = 0;        /* if emission occur */
}               /* clear emission flag for next emission*/


/*
==========================
SEC 4.0 helper functions
==========================
*/

/*
putchar is called by printf();
*/
//int putchar(int c)
void putchar( char  c)
{
	while(!(SCON & 0x02));
	SCON &= ~0x02;
	SBUF = c & 0xff;
	//return (c);
}

/*
==========================
SEC 5.0 main function
==========================
*/

void main(void)
{
	unsigned long int i = 0;
	short x ; 
/*	
;*************************************************
;		UART 115200bps
;*************************************************
		ORL	CKCON0,#00000001B	; 6 CLK PERIOD/MACHINE
		ORL	PCON,#11000000B		; ENABLE THE FRAMING BIT ERROR DETECTION, DOUBLE BAUD RATE
								; AND CHECK FE BIT OF SCON SFR
		ORL	BDRCON,#00001110B	; SPD=1,RBCK =1, TBCK =1
		MOV	SCON,#01010000B		; uart in mode 1 (8 bit), REN=1 
		MOV	BRL,#243			; U CAN SEE THIS VALUE FROM PAGE 71 OF DATASHEET
		ORL	BDRCON,#00010000B	; BRR = 1 , START BAUD RATE RUN
*/  
	// this works.
	CKCON0 = 1;
	PCON   = 0xC0;
	BDRCON = 0x0E;
	SCON   = 0X50;
	BRL    = 0xF3; // 243;
	
	BDRCON = BDRCON | 0x10;
  
//	TCON |= 0x40;
	SCON |= 0x02;				// Tell putchar() the UART is ready to send.

    ES  = 1;     /* Enable serial interrupt */
	
	/* enable INT0 interrupt */
	P3_2  = 1;
	TMOD = 0x08;   // PORT3.2 use set GATE0 in TMOD.
	
	IT0	= 1;	 /* 1 = edge, 0 = low */
	EX0 = 1; 	 /* enable INT0 */
	EX1 = 1;
	ES  = 1;
    EA  = 1;     /* Enable global interrupt */


	P0 = 0xff;
	P1 = 0xff;
	P2 = 0xff;
	P3 = 0xff;
	
    x = 0x0 ;  
	//intCounter = 0;
	for(;;)
	{
		// set PORT 0 to count LED. PORT 0 is open drain. 
		x++;
		P0 = x+x | ( ~( intCounter > 0 ) & 1) ; 
		printf("UUU 555   Hello World! x= %04X     %04x %d %d %d \n\r",x ,intCounter ,IE0 ,IT0 ,P3_2 );
		printf("IEN0: %02x TCON: %02x TMOD: %02x SCON: %02x RI: %02x TI: %02x %02x \n\r",IEN0 ,TCON, TMOD, SCON, RI ,TI ,uart_data );
		if ( intCounter > 0 ){
		  intCounter += -1;
        }
		
//		for(i = 0; i < 147456; i++); // Sleep
		for(i = 0; i < 14745; i++); // Sleep
	}
}