Introduction to Embedded SystemsLecture 1These lecture notes created by Alex Dean, NCSUTodayWhat Are Embedded Systems?Why Are We ….?Course OverviewIntroduction to Microcontroller-based Circuit DesignEmbedded Systems 1-2Embedded Systems 1-3Definition of an Embedded ComputerComputer purchased as part of some other piece of equipment– Typically dedicated software (may be user-customizable)– Often replaces previously electromechanical components– Often no “real” keyboard– Often limited display or no general-purpose display deviceEmbedded Systems 1-4But, every system is unique -- there are always exceptionsA Customer ViewEmbedded Systems 1-5Reduced CostIncreased FunctionalityImproved PerformanceIncreased Overall DependabilityMicrocontroller and Starter KitMitsubishi Semiconductors is now “Renesas”M16C/26 family of microcontrollers–M30626Embedded Systems 1-6–M30626– 32K RAM, 384K FlashSKP = starter kit MDS = Microcontroller Data Sheet = M16C_Hardware_Manual_Rev0.9.pdfM16C DemonstrationConfiguring I/O ports– Input: switches– Output: LEDsEcho switch state on LEDsHuman response time analysis–How quickly can a person press a switch after seeing a light?Embedded Systems 1-7–How quickly can a person press a switch after seeing a light?Processor response time analysis– How quickly does the processor respond to the switch being pressed?Processor speed evaluation– How much work can the processor do in that time?Source Code#include "stdio.h"#include "stdio.h"#include "stdio.h"#include "stdio.h"#include "sfr626.h"#include "sfr626.h"#include "sfr626.h"#include "sfr626.h"#include "SKP_LCD.h"#include "SKP_LCD.h"#include "SKP_LCD.h"#include "SKP_LCD.h"#define RED_LED (p8_0) /* from board data sheet */#define RED_LED (p8_0) /* from board data sheet */#define RED_LED (p8_0) /* from board data sheet */#define RED_LED (p8_0) /* from board data sheet */#define YEL_LED (p7_4) #define YEL_LED (p7_4) #define YEL_LED (p7_4) #define YEL_LED (p7_4) #define GRN_LED (p7_2) #define GRN_LED (p7_2) #define GRN_LED (p7_2) #define GRN_LED (p7_2) #define LED_ON (0) /* 0 is ON for LEDs (active#define LED_ON (0) /* 0 is ON for LEDs (active#define LED_ON (0) /* 0 is ON for LEDs (active#define LED_ON (0) /* 0 is ON for LEDs (active----low) */low) */low) */low) */#define LED_OFF (1)#define LED_OFF (1)#define LED_OFF (1)#define LED_OFF (1)#define DIR_IN (0)#define DIR_IN (0)#define DIR_IN (0)#define DIR_IN (0)#define DIR_OUT (1)#define DIR_OUT (1)#define DIR_OUT (1)#define DIR_OUT (1)#define SW1 (p8_3)#define SW1 (p8_3)#define SW1 (p8_3)#define SW1 (p8_3)#define SW2 (p8_2)#define SW2 (p8_2)#define SW2 (p8_2)#define SW2 (p8_2)#define SW3 (p8_1)#define SW3 (p8_1)#define SW3 (p8_1)#define SW3 (p8_1)void main () {void main () {void main () {void main () {char buf[9];char buf[9];char buf[9];char buf[9];long int i, r=12345;long int i, r=12345;long int i, r=12345;long int i, r=12345;init_switches();init_switches();init_switches();init_switches();init_LEDs();init_LEDs();init_LEDs();init_LEDs();InitDisplay();InitDisplay();InitDisplay();InitDisplay();#if (1)#if (1)#if (1)#if (1)test_switches();test_switches();test_switches();test_switches();#endif#endif#endif#endifDisplayString(LCD_LINE1, "Response");DisplayString(LCD_LINE1, "Response");DisplayString(LCD_LINE1, "Response");DisplayString(LCD_LINE1, "Response");DisplayString(LCD_LINE2, " Timer ");DisplayString(LCD_LINE2, " Timer ");DisplayString(LCD_LINE2, " Timer ");DisplayString(LCD_LINE2, " Timer ");while(1) {while(1) {while(1) {while(1) {for (i=0; i<200000+(r%50000); i++)for (i=0; i<200000+(r%50000); i++)for (i=0; i<200000+(r%50000); i++)for (i=0; i<200000+(r%50000); i++); ; ; ; i=0;i=0;i=0;i=0;RED_LED = YEL_LED = GRN_LED = LED_ON;RED_LED = YEL_LED = GRN_LED = LED_ON;RED_LED = YEL_LED = GRN_LED = LED_ON;RED_LED = YEL_LED = GRN_LED = LED_ON;Embedded Systems 1-8void init_switches() {void init_switches() {void init_switches() {void init_switches() {pd8_1 = pd8_2 = pd8_3 = DIR_IN;pd8_1 = pd8_2 = pd8_3 = DIR_IN;pd8_1 = pd8_2 = pd8_3 = DIR_IN;pd8_1 = pd8_2 = pd8_3 = DIR_IN;}}}}void init_LEDs() {void init_LEDs() {void init_LEDs() {void init_LEDs() {pd8_0 = pd7_4 = pd7_2 = DIR_OUT;pd8_0 = pd7_4 = pd7_2 = DIR_OUT;pd8_0 = pd7_4 = pd7_2 = DIR_OUT;pd8_0 = pd7_4 = pd7_2 = DIR_OUT;RED_LED = YEL_LED = GRN_LED = LED_ON; RED_LED = YEL_LED = GRN_LED = LED_ON; RED_LED = YEL_LED = GRN_LED = LED_ON; RED_LED = YEL_LED = GRN_LED = LED_ON; RED_LED = YEL_LED = GRN_LED = LED_OFF; RED_LED = YEL_LED = GRN_LED = LED_OFF; RED_LED = YEL_LED = GRN_LED = LED_OFF; RED_LED = YEL_LED = GRN_LED = LED_OFF; }}}}void test_switches(void) {void test_switches(void) {void test_switches(void) {void test_switches(void) {while (1) {while (1) {while (1) {while (1) {RED_LED = (!SW1)? LED_ON : LED_OFF;RED_LED = (!SW1)? LED_ON : LED_OFF;RED_LED = (!SW1)? LED_ON : LED_OFF;RED_LED = (!SW1)? LED_ON : LED_OFF;YEL_LED = (!SW2)? LED_ON : LED_OFF;YEL_LED = (!SW2)? LED_ON : LED_OFF;YEL_LED = (!SW2)? LED_ON : LED_OFF;YEL_LED = (!SW2)? LED_ON : LED_OFF;GRN_LED = (!SW3)? LED_ON : LED_OFF;GRN_LED = (!SW3)? LED_ON : LED_OFF;GRN_LED = (!SW3)? LED_ON : LED_OFF;GRN_LED = (!SW3)? LED_ON : LED_OFF;}}}}}}}}RED_LED = YEL_LED = GRN_LED = LED_ON;RED_LED = YEL_LED = GRN_LED = LED_ON;RED_LED = YEL_LED = GRN_LED = LED_ON;RED_LED = YEL_LED = GRN_LED = LED_ON;while (SW1)while (SW1)while (SW1)while (SW1)i++;i++;i++;i++;#if (1) #if (1) #if (1) #if (1) sprintf(buf, "%8ld", i);sprintf(buf, "%8ld", i);sprintf(buf, "%8ld", i);sprintf(buf, "%8ld", i);DisplayString(LCD_LINE1, buf);DisplayString(LCD_LINE1, buf);DisplayString(LCD_LINE1, buf);DisplayString(LCD_LINE1, buf);DisplayString(LCD_LINE2, "iters. ");DisplayString(LCD_LINE2, "iters. ");DisplayString(LCD_LINE2, "iters. ");DisplayString(LCD_LINE2, "iters. ");#else#else#else#elsesprintf(buf, "%8.3f", i*39.1/287674);sprintf(buf, "%8.3f", i*39.1/287674);sprintf(buf, "%8.3f", i*39.1/287674);sprintf(buf, "%8.3f", i*39.1/287674);DisplayString(LCD_LINE1, buf);DisplayString(LCD_LINE1, buf);DisplayString(LCD_LINE1, buf);DisplayString(LCD_LINE1, buf);DisplayString(LCD_LINE2, "millisec");DisplayString(LCD_LINE2, "millisec");DisplayString(LCD_LINE2, "millisec");DisplayString(LCD_LINE2, "millisec");#endif #endif #endif #endif RED_LED = YEL_LED = GRN_LED = LED_OFF; RED_LED = YEL_LED = GRN_LED = LED_OFF; RED_LED = YEL_LED = GRN_LED = LED_OFF; RED_LED = YEL_LED = GRN_LED = LED_OFF; r=0;r=0;r=0;r=0;while (!SW1) /* wait for switch to
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