Things 8051

Merging all my notes related to 8051-based system development.

My personal code library for 8051 is available at codeberg.org.

Core 8051

Microcontroller/board info.

Board51:stc15w204s (8-pin)

Picture

stc15w204s front stc15w204s back

Block diagram

stc15w204s pins

May need proper USB2serial cable (e.g. PL2303-based)

stc15w204s pins

2026/02/09 22:23

Code 8051

Example codes (in C) for the classical Intel-8051 (mcu51) microcontroller core. Using my1code51 library. Tested using sdcc open source compiler and stc12 device.

Code: IR module and Ultrasonic sensor module

Testing IR module and HC-SR04 ultrasonic sensor module.

test0_ir_hc.c

/*----------------------------------------------------------------------------*/
#include "uart.h"
#include "timer.h"
#define FPSIZE 2
#include "utils_float.h"
#define _LCD_4BIT_INTERFACE_
/** DB4-DB7 => P0 (UPPER NIBBLE) */
/** E => P0.2 : NEEDS -ve EDGE */
/** R/W => P0.1 : 0=WR 1=RD */
/** RS => P0.0 : 0=CMD 1=DAT */
#include "textlcd.h"
/*----------------------------------------------------------------------------*/
/**
 * Testing IR module and HC-SR04 ultrasonic sensor module
 * - display on both uart and lcd
**/
/*----------------------------------------------------------------------------*/
MY1SBIT(IRMOD,PIN10);
MY1SBIT(TRIG,PIN16);
MY1SBIT(ECHO,PIN17);
/*----------------------------------------------------------------------------*/
MY1SBIT(TEST_IR,PIN14);
MY1SBIT(TEST_HC,PIN15);
/*----------------------------------------------------------------------------*/
#define FLAG_IR 0x01
#define FLAG_HC 0x02
/*----------------------------------------------------------------------------*/
void main(void) {
	unsigned char wait;
	unsigned int tval,loop, flag;
	float fval, dist;
	char buff[16];
	uart_init();
	uart_puts("\r\nTESTING NMK322 STUFFS\r\n");
	lcd_init();
	lcd_goto_line1();
	lcd_puts("TESTKIT 4 NMK322");
	timer_init();
	flag = 0;
	while (1) {
		if (TEST_IR==0) {
			if ((flag&FLAG_IR)==0) {
				lcd_goto_line1();
				lcd_puts("TEST 4 IR MODULE");
				uart_puts("\r\nTESTING IR MODULE\r\n");
				flag = FLAG_IR;
			}
			lcd_goto_line2();
			lcd_puts("                ");
			lcd_goto_line2();
			lcd_puts("Waiting... ");
			uart_puts("\r\nWaiting... ");
			while (IRMOD); // outputs logic low when obstacle detected
			lcd_puts("|*");
			uart_puts("|*");
			while (!IRMOD);
			lcd_puts("|");
			uart_puts("|\r\n");
			for (loop=65000;loop;loop--);
		}
		if (TEST_HC==0) {
			if ((flag&FLAG_HC)==0) {
				lcd_goto_line1();
				lcd_puts("TEST HC-SR04 MOD");
				uart_puts("\r\nTESTING HC-SR04 MODULE\r\n");
				flag = FLAG_HC;
			}
			lcd_goto_line2();
			lcd_puts("                ");
			lcd_goto_line2();
			timer_prep(0);
			TRIG = 1;
			for (wait=10;wait;wait--); // arounf 10us?
			TRIG = 0;
			while (!ECHO); timer_exec();
			while (ECHO); timer_stop();
			tval = ((unsigned int)TH0<<8)|TL0;
			fval = (float)tval * 1.085; // in us
			dist = fval / 58.0; // in cm
			lcd_puts("Dist:");
			uart_puts("-- Distance=");
			float2str(buff,dist);
			lcd_puts(buff);
			lcd_puts("cm");
			uart_puts(buff);
			uart_puts(" cm\r\n");
			for (loop=65000;loop;loop--);
		}
	}
}
/*----------------------------------------------------------------------------*/

Code: BT module and servo

Testing HC06 bluetooth module , TowerPro MG996R servo.

test1_btservo.c

/*----------------------------------------------------------------------------*/
/**
 * Testing HC06 bluetooth module , TowerPro MG996R servo
 * - note: servo pin (1|orange:PWM)(2|red:vcc)(3|brown:ground)
**/
/*----------------------------------------------------------------------------*/
#define APPTITLE "NMK322 BT/SERVO"
#define BTNAME "nmk322bt"
#define BTPASS "0000"
#include "hc06.h"
#include "hc06_conf.h"
#include "uart.h"
#include "uart_hexascii.h"
#include "timer.h"
#include "utils.h"
#include "oled_ssd1306.h"
#include "cstr_hexascii.h"
/*----------------------------------------------------------------------------*/
#define OLED_ROW_DATA 2
#define OLED_ROW_INFO1 4
#define OLED_ROW_INFO2 6
/*----------------------------------------------------------------------------*/
#define SERVO_PIN P1_0
#include "servo.h"
/*----------------------------------------------------------------------------*/
_sbit(GO000,PIN15);
_sbit(GO1MS,PIN16);
_sbit(GO2MS,PIN17);
/*----------------------------------------------------------------------------*/
#define BUFFSIZE 128
/*----------------------------------------------------------------------------*/
__xdata char buff[BUFFSIZE];
/*----------------------------------------------------------------------------*/
void uart_show_buff(void) {
	char* pchk = buff;
	while (*pchk) {
		if (pchk[0]<0x20||pchk[0]>0x7e) {
			uart_puts("[0x");
			uart_send_hexbyte(pchk[0]);
			uart_send(']');
		}
		else uart_send(pchk[0]);
		pchk++;
	}
	uart_send('\n');
}
/*----------------------------------------------------------------------------*/
void main(void) {
	unsigned char curr, test;
	GO000 = 1; GO1MS = 1; GO2MS = 1;
	timer_init();
	servo_init();
	i2c_init();
	oled1306_init();
	oled1306_puts(APPTITLE);
	uart_init();
	uart_puts("\n---------------\n");
	uart_puts(APPTITLE);
	uart_puts("\n---------------\n\n");
	hc06_init();
	curr = 3;
	do {
		uart_puts("-- Looking for HC06... ");
		oled1306_set_cursor(OLED_ROW_INFO1,0);
		oled1306_puts("Finding HC06... ");
		hc06_find();
		if (hc06_wait_ok()==HC06_OK) {
			uart_puts("OK.\r\n");
			oled1306_puts("OK");
			oled1306_set_cursor(OLED_ROW_INFO2,0);
			oled1306_puts("Setting up HC06... ");
			uart_puts("\r\nSet default name & pin\r\n");
			uart_puts("-- Set Name (");
			uart_puts(BTNAME);
			uart_puts("): ");
			hc06_setname(buff,BUFFSIZE);
			uart_puts(buff);
			uart_puts("\r\n");
			timer_delay1s(test,1);
			/* set pass */
			uart_puts("-- Set Pin (");
			uart_puts(BTPASS);
			uart_puts("): ");
			hc06_setpin(buff,BUFFSIZE);
			uart_puts(buff);
			uart_puts("\r\n");
			timer_delay1s(test,1);
			oled1306_puts("OK");
			timer_delay1s(test,1);
			oled1306_clear_row(OLED_ROW_INFO1);
			oled1306_clear_row(OLED_ROW_INFO2);
			break;
		}
		uart_puts("timeout.\n");
		timer_delay1s(test,1);
	} while (--curr);
	while (1) {
		if (hc06_peek()) {
			if ((test=hc06_wait(buff,BUFFSIZE))>1) {
				if (buff[0]=='#') {
					if (test==BUFFSIZE) test--;
					buff[test] = 0x0;
					while (buff[test-1]=='\r'||buff[test-1]=='\n') {
						test--;
						buff[test] = 0x0;
					}
					curr = (unsigned char) str2uint(&buff[1]);
					if (curr>=5&&curr<=25) {
						uart_puts("## Turning to (");
						uart_puts(&buff[1]);
						uart_puts(")\r\n");
						oled1306_set_cursor(OLED_ROW_DATA,0);
						oled1306_puts("ServoTurn: ");
						oled1306_puts(&buff[1]);
						servo_turn(curr);
						timer_delay1s(test,1);
						oled1306_clear_row(OLED_ROW_DATA);
					}
					else {
						uart_puts("** Invalid angle (");
						uart_puts(&buff[1]);
						uart_puts(")\r\n");
					}
				}
				else {
					uart_puts(">> ");
					uart_puts(buff);
					uart_puts("\r\n");
				}
			}
		}
		if (GO000==0) {
			oled1306_set_cursor(OLED_ROW_DATA,0);
			oled1306_puts("ServoTurn CENTER");
			servo_turn(15);
			while (!GO000);
			oled1306_clear_row(OLED_ROW_DATA);
		}
		if (GO1MS==0) {
			oled1306_set_cursor(OLED_ROW_DATA,0);
			oled1306_puts("ServoTurn PWM1ms");
			servo_turn(10); // 1ms pwm
			while (!GO1MS);
			oled1306_clear_row(OLED_ROW_DATA);
		}
		if (GO2MS==0) {
			oled1306_set_cursor(OLED_ROW_DATA,0);
			oled1306_puts("ServoTurn PWM2ms");
			servo_turn(20); // 2ms pwm
			while (!GO2MS);
			oled1306_clear_row(OLED_ROW_DATA);
		}
	}
}
/*----------------------------------------------------------------------------*/

Testing HC06 bluetooth module , TowerPro MG996R servo & Text LCD.

test1_btservolcd.c

/*----------------------------------------------------------------------------*/
/**
 * Testing HC06 bluetooth module , TowerPro MG996R servo & Text LCD
 * - note: servo pin (1|orange:PWM)(2|red:vcc)(3|brown:ground)
**/
/*----------------------------------------------------------------------------*/
#define BTNAME "nmk322bt"
#define BTPASS "0000"
#include "hc06.h"
#include "uart.h"
#include "timer.h"
#include "utils.h"
/*----------------------------------------------------------------------------*/
/** interface as defined in nmk322 lab module */
#define _LCD_8BIT_INTERFACE_
#define _LCD_PINS_DEFINED_
MY1SFR(LCD_DATA,0xA0);
MY1SBIT(LCD_BUSY,0xA7);
MY1SBIT(LCD_DNC,0x87);
MY1SBIT(LCD_RNW,0x86);
MY1SBIT(LCD_ENB,0x85);
/*----------------------------------------------------------------------------*/
#include "textlcd.h"
/*----------------------------------------------------------------------------*/
#define SERVO_PIN P1_0
#include "servo.h"
/*----------------------------------------------------------------------------*/
MY1SBIT(GO000,PIN15);
MY1SBIT(GO1MS,PIN16);
MY1SBIT(GO2MS,PIN17);
/*----------------------------------------------------------------------------*/
#define BUFFSIZE 128
/*----------------------------------------------------------------------------*/
__xdata char buff[BUFFSIZE];
/*----------------------------------------------------------------------------*/
void main(void) {
	unsigned char curr, test;
	GO000 = 1; GO1MS = 1; GO2MS = 1;
	timer_init();
	servo_init();
	lcd_init();
	lcd_goto_line1();
	lcd_puts("NMK322 SV/LCD/BT");
	uart_init();
	uart_puts("NMK322 SV/LCD/BT\r\n\r\n");
	hc06_init();
	curr = 3;
	do {
		uart_puts("-- Sending AT... ");
		hc06_find();
		if (hc06_wait_ok()==HC06_OK) {
			uart_puts("OK.\r\n");
			uart_puts("\r\nSet default name & pin\r\n");
			uart_puts("-- Set Name (");
			uart_puts(BTNAME);
			uart_puts("): ");
			hc06_setname(buff,BUFFSIZE);
			uart_puts(buff);
			uart_puts("\r\n");
			timer_delay1s(test,1);
			/* set pass */
			uart_puts("-- Set Pin (");
			uart_puts(BTPASS);
			uart_puts("): ");
			hc06_setpin(buff,BUFFSIZE);
			uart_puts(buff);
			uart_puts("\r\n");
			timer_delay1s(test,1);
			break;
		}
		uart_puts("timeout.\n");
		timer_delay1s(test,1);
	} while (--curr);
	while (1) {
		if (hc06_peek()) {
			if (hc06_wait(buff,BUFFSIZE)>1) {
				if (buff[0]=='#') {
					curr = (unsigned char) str2uint(&buff[1]);
					if (curr>=5&&curr<=25) {
						uart_puts("## Turning to (");
						uart_puts(&buff[1]);
						uart_puts(")\r\n");
						servo_turn(curr);
					} else {
						uart_puts("** Invalid angle (");
						uart_puts(&buff[1]);
						uart_puts(")\r\n");
					}
				} else {
					uart_puts(">> ");
					uart_puts(buff);
					uart_puts("\r\n");
				}
			}
		}
		if (GO000==0) {
			lcd_goto_line2();
			lcd_puts("ServoTurn CENTER");
			servo_turn(15);
			while (!GO000);
			lcd_goto_line2();
			lcd_puts("                ");
		}
		if (GO1MS==0) {
			lcd_goto_line2();
			lcd_puts("ServoTurn PWM1ms");
			servo_turn(10); // 1ms pwm
			while (!GO1MS);
			lcd_goto_line2();
			lcd_puts("                ");
		}
		if (GO2MS==0) {
			lcd_goto_line2();
			lcd_puts("ServoTurn PWM2ms");
			servo_turn(20); // 2ms pwm
			while (!GO2MS);
			lcd_goto_line2();
			lcd_puts("                ");
		}
	}
}
/*----------------------------------------------------------------------------*/

Code: RFID module and OLED

Testing RFID (FRC522) and OLED (ssd1306).

test2_rfid.c

/*----------------------------------------------------------------------------*/
#include "uart_hexascii.h"
#include "oled_ssd1306.h"
#include "cstr_hexascii.h"
#include "frc522.h"
#define APPTITLE "NMK322 RFID/OLED"
/*----------------------------------------------------------------------------*/
void main(void) {
	__xdata cstr_t buff; /* default: 64-bytes long */
	unsigned char temp, stat, loop, size;
	unsigned char pdat[FRC522_MAX_RXSIZE], reqa[2];
	/** initialize */
	cstr_init(&buff);
	uart_init();
	i2c_init();
	oled1306_init();
	spi_init();
	atqa = reqa;
	/* initialize mf contactless card reader */
	/** say something... */
	uart_puts("\n----------------\n");
	uart_puts(APPTITLE);
	uart_puts("\n----------------\n\n");
	oled1306_puts(APPTITLE);
	temp = frc522_init();
	if (!temp||temp==0xff) {
		uart_puts("** Cannot find FRC522 hardware! Aborting!\n");
		oled1306_set_cursor(5,0);
		oled1306_puts("** Hardware Error!");
		hang();
	}
	uart_puts("FRC522 found. Firmware version is 0x");
	uart_send_hexbyte(temp);
	uart_puts(".\n");
	cstr_null(&buff);
	cstr_append(&buff,"FW Vers: 0x");
	cstr_append_hexbyte(&buff,temp);
	oled1306_set_cursor(5,0);
	oled1306_puts(buff.buff);
	/** main loop */
	while (1) {
		stat = frc522_scan(pdat,&size);
		if (stat==FRC522_OK) {
			uart_puts("## TAG(");
			uart_send_hexbyte(stat);
			uart_puts("|");
			uart_send_hexbyte(reqa[0]);
			uart_puts(",");
			uart_send_hexbyte(reqa[1]);
			uart_puts("):");
			cstr_null(&buff);
			for (loop=0;loop<size-1;loop++) { /** UID is size-1 bytes */
				uart_send('[');
				uart_send_hexbyte(pdat[loop]);
				cstr_append_hexbyte(&buff,pdat[loop]);
				uart_send(']');
			}
			uart_send('\n');
			oled1306_set_cursor(2,0);
			oled1306_puts("#TAG: ");
			oled1306_puts(buff.buff);
			loop_delay(3000);
			oled1306_clear_row(2);
		}
		else if (stat!=FRC522_ERROR_NO_TAG&&stat!=FRC522_ERROR_REQ_A) {
			uart_puts("** Scan Failed (0x");
			uart_send_hexbyte(stat);
			uart_puts("):");
			for (loop=0;loop<FRC522_MAX_RXSIZE;loop++) {
				uart_send('[');
				uart_send_hexbyte(pdat[loop]);
				uart_send(']');
			}
			uart_send('\n');
			oled1306_set_cursor(3,0);
			oled1306_puts("*TAG: ERROR!");
			loop_delay(3000);
			oled1306_clear_row(3);
		}
	}
}
/*----------------------------------------------------------------------------*/

Code: Testing Base Kit

Testing Base Kit (202425s1).

Code: gtuc51

Test code for the old GTUC51B001 development board.

gtuc51.c

/*----------------------------------------------------------------------------*/
/**
 * Demo program for gtuc51 (with io board)
**/
/*----------------------------------------------------------------------------*/
#include "adc0831.h"
#include "keypad_922.h"
#include "textlcd.h"
#include "utils_float.h"
/*----------------------------------------------------------------------------*/
/**
 * Switch & LED Interface for gtuc51 i/o board
 *   - multiplexed (dual/purpose)
 *   - require jumper link settings!
**/
/** SW0, SW1 => P3.3, P3.2 - LAYOUT ERROR */
__sbit __at (0xB3) SW0;
__sbit __at (0xB2) SW1;
/** LED{0-3} => P3.4-P3.7 */
__sbit __at (0xB4) LED0;
__sbit __at (0xB5) LED1;
__sbit __at (0xB6) LED2;
__sbit __at (0xB7) LED3;
/** LED{RX,TX} => P3.1, P3.0 - LAYOUT ERROR */
__sbit __at (0xB1) LEDRX;
__sbit __at (0xB0) LEDTX;
/** alias LEDX=-2 and LEDY=-1 (LEFT OF LED0) **/
__sbit __at (0xB1) LEDX;
__sbit __at (0xB0) LEDY;
/*----------------------------------------------------------------------------*/
char display[LCD_MAX_CHAR];
unsigned char lcdi, loop;
float value;
keybyte_t keyin;
adcbyte_t check;
__bit adc, adcgo, left, demo;
/*----------------------------------------------------------------------------*/
#define DEMO_IO 1
#define DEMO_ADC 0
/*----------------------------------------------------------------------------*/
#define LOOP_COUNT 20
/*----------------------------------------------------------------------------*/
/* interrupt service routine for timer0 */
void timer_blink(void) __interrupt TF0_VECTOR {
	TR0 = 0; loop--;
	P1 = ~P1;
	if (loop==0) {
		if (!left) {
			loop = LED0; LED0 = LED1; LED1 = LED2; LED2 = LED3;
			LED3 = LEDX; LEDX = LEDY; LEDY = loop;
		}
		else {
			loop = LED3; LED3 = LED2; LED2 = LED1; LED1 = LED0;
			LED0 = LEDY; LEDY = LEDX; LEDX = loop;
		}
		loop = LOOP_COUNT;
	}
	TH0 = 0x4B; TL0 = 0xFD; TR0 = 1; /** 50ms */
}
/*----------------------------------------------------------------------------*/
/* interrupt service routine for timer1 */
void timer_goadc(void) __interrupt TF1_VECTOR {
	TR1 = 0; TH1 = 0x4B; TL1 = 0xFD;
	if (loop>0) {
		TR1 = 1; /** 50ms */
		loop--;
	}
	else {
		loop = LOOP_COUNT;
		adcgo = adc;
	}
}
/*----------------------------------------------------------------------------*/
/* interrupt service routine for int1 */
void check_switch0(void) __interrupt IE1_VECTOR {
	left = 0;
	if (lcdi<LCD_MAX_CHAR) {
		lcd_data(0x30);
		lcdi++;
	}
}
/*----------------------------------------------------------------------------*/
/* interrupt service routine for int0 */
void check_switch1(void) __interrupt IE0_VECTOR {
	left = 1;
	if (lcdi<LCD_MAX_CHAR) {
		lcd_data(0x31);
		lcdi++;
	}
}
/*----------------------------------------------------------------------------*/
/* main function */
void main(void) {
	/** initalize stuffs */
	demo = DEMO_IO; /* default... just in case */
	TMOD = 0x11; P1 = 0xFF; P3 = 0xFF;
	lcd_init();
	lcd_goto_line1();
	lcd_puts("8051 Select Demo");
	lcd_goto_line2();
	lcd_puts("[SW0]IO [SW1]ADC");
	/* wait for user key press */
	while (1) {
		if (!SW0) {
			demo = DEMO_IO; /* demo switch, led, keypad and P1 */
			while(!SW0); /** wait until the user press & let go */
			break;
		}
		else if (!SW1) {
			demo = DEMO_ADC; /* demo adc */
			while(!SW1);
			break;
		}
	}
	/* select! */
	if (demo==DEMO_IO) {
		lcd_goto_line1();
		lcd_puts("MY18051 I/O DEMO");
		lcd_goto_line2();
		lcd_puts("                ");
		lcd_goto_line2();
		/** set timer 0 overflow every 50ms - with interrupt handler */
		loop = LOOP_COUNT; lcdi = 0; left = 0;
		P1 = 0xAA; LED0 = 0; IT0 = 1; IT1 = 1;
		EA = 1; ET0 = 1; EX0 = 1; EX1 = 1;
		TH0 = 0x4B; TL0 = 0xFD; TR0 = 1;
		/** main loop */
		while (1) {
			keyin = key_wait_922();
			if (keyin<10&&lcdi<LCD_MAX_CHAR) { /** numeric key! */
				lcd_data(keyin+0x30);
				lcdi++;
			}
			else if(keyin==0x0F) { /** '#' key! */
				lcd_goto_line2();
				lcd_puts("HASHED!         ");
				lcd_goto_line2();
				lcdi = LCD_MAX_CHAR;
			}
			else if(keyin==0x0E) { /** '*' key! */
				lcd_goto_line2();
				lcd_puts("                ");
				lcd_goto_line2();
				lcdi = 0;
			}
		}
	}
	else {
		lcd_goto_line1();
		lcd_puts("MY18051 ADC DEMO");
		lcd_goto_line2();
		lcd_puts("SW0:ADC, SW1:CLR");
		/* initialize adc */
		adc_init();
		adc = 0; adcgo = 0; EA = 1;
		/** adc status indicator */
		LEDRX = adc; LEDTX = !adc;
		/** main loop */
		while (1) {
			if (!SW0) {
				while (!SW0); /** wait until the user lets go */
				adc = !adc;
				adcgo = adc;
				if (!adcgo) {
					ET1 = 0; TR1 = 0;
					lcd_puts("*");
				}
				LEDRX = adc; LEDTX = !adc;
			}
			else if(!SW1) {
				while (!SW1); /** wait until the user lets go */
				lcd_goto_line2();
				lcd_puts("SW0:ADC, SW1:CLR");
			}
			if (adcgo) {
				adcgo = 0;
				lcd_goto_line2();
				lcd_puts("                ");
				/** read adc */
				check = adc_get_data();
				value = ((float) check / 255.0) * VREF;
				lcd_goto_line2();
				lcd_puts("ADC: ");
				float2str(display,value);
				lcd_puts(display);
				lcd_puts(" (");
				int2str(display,check);
				lcd_puts(display);
				lcd_puts(")");
				/** set timer 1 overflow every 50ms - with interrupt handler */
				ET1 = 1; TH1 = 0x4B; TL1 = 0xFD; TR1 = 1;
			}
		}
	}
}
/*----------------------------------------------------------------------------*/