> For the complete documentation index, see [llms.txt](https://ykkim.gitbook.io/EC/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://ykkim.gitbook.io/EC/ec-course/lab/mbed-mini-fan.md). # LAB: Portable Fan with mbed ### Problem An automatic mini-fan that runs only when the face is near the fan 1. As the button B1 is pressed, change the DC motor velocity * The mode is OFF(0%), MID(50%), HIGH(100%) * As the B1 is pressed, it should toggle from OFF mode to HIGH mode and so on 2\. Automatically ReStart and Stop the DC motor when the mode is * CONT: The distance is within about 50mm * PAUSE: The distance is beyond about 50mm ### State Diagram ![](/files/-MkkLhNEHpsNToMnKz7-) ### Method 1 (Recommended) Using structure variable for state definition ```cpp // created by Y.K Kim #include "mbed.h" // State Definition #define OFF 0 #define MID 1 #define HIGH 2 // State Input Definition #define IN_CONT 1 #define IN_PAUSE 0 typedef struct { uint32_t out; uint32_t next[3]; } State_t; State_t FSM[4] = { {0, {OFF,MID}}, {5, {MID,HIGH}}, {10, {HIGH,OFF}} }; int state = OFF; int stateInput = IN_CONT; int stTime = 0; int endTime = 0; int bNextState = 0; int bPressed=0; InterruptIn button(USER_BUTTON); DigitalOut led(LED1); PwmOut pwm1(D11); Serial pc(USBTX, USBRX, 9600); PwmOut trig(D10); // Trigger 핀 InterruptIn echo(D7); // Echo 핀 Timer tim; void nextState(int _state, int input) { double pwm; state=_state; if (bPressed) state = FSM[_state].next[stateInput]; // Next State bPressed=0; if (stateInput == IN_CONT) pwm = FSM[state].out; else pwm = 0; pwm1.pulsewidth_ms(pwm); if (state == OFF) led = 0; else led = 1; } void pressed() { bPressed=1; nextState(state, stateInput); } void setup(void) { pwm1.period_ms(10); trig.period_ms(60); // period = 60ms trig.pulsewidth_us(10); // pulse-width = 10us } void rising() { stTime = tim.read_us(); } void falling() { endTime = tim.read_us(); } int main() { int thresh = 5; float distance = 0; setup(); // BT interrupt button.fall(&pressed); // InputCapture interrupt echo.rise(&rising); echo.fall(&falling); // Start time measurement tim.start(); while (1) { // Check distance distance = abs((float)(endTime - stTime)) / 58; // [cm] if (distance > thresh) { if (stateInput != IN_PAUSE) bNextState = 1; stateInput = IN_PAUSE; } else { if (stateInput != IN_CONT) bNextState = 1; stateInput = IN_CONT; } // change state only if there is a change in the input //if (bNextState) nextState(state,stateInput); bNextState = 0; printf("input = %d, state = %d, distance = %.2f\r\n",stateInput, state, distance); wait(0.1); } } ``` ### Method 2 Using case switch for next state definition ```cpp // Method 1 // by Y.K Kim #include "mbed.h" // State Definition #define OFF 0 #define MID 1 #define HIGH 2 // State Input Definition #define IN_CONT 1 #define IN_PAUSE 0 int state=0; int stateInput = 0; int stTime = 0; int endTime = 0; int bNextState = 0; int bPressed=0; InterruptIn button(USER_BUTTON); DigitalOut led(LED1); PwmOut pwm1(D11); Serial pc(USBTX, USBRX, 9600); PwmOut trig(D10); // Trigger 핀 InterruptIn echo(D7); // Echo 핀 Timer tim; // Mealy FSM void outputState(int _state, int input) { if (_state == OFF) led = 0; else led = 1; if (!input) pwm1.pulsewidth_ms(0); else pwm1.pulsewidth_ms(_state * 5); } void nextState(int _state, int input) { int nextstate = 0; state=_state; if (bPressed){ switch (_state) { case 0: case 1: if (input) nextstate = _state + 1; else nextstate=_state; break; case 2: if (input) nextstate = 0; else nextstate = _state; break; } state = nextstate; } outputState(state, input); bPressed=0; } void pressed() { bPressed=1; nextState(state, stateInput); } void setup(void) { pwm1.period_ms(10); trig.period_ms(60); // period = 60ms trig.pulsewidth_us(10); // pulse-width = 10us } void rising() { stTime = tim.read_us(); } void falling() { endTime = tim.read_us(); } int main() { int thresh = 5; float distance = 0; setup(); // BT interrupt button.fall(&pressed); // InputCapture interrupt echo.rise(&rising); echo.fall(&falling); // Start time measurement tim.start(); while (1) { // Check distance distance = (float)(endTime - stTime) / 58; // [cm] if (distance > thresh){ if (stateInput != IN_PAUSE) bNextState = 1; stateInput = IN_PAUSE; } else { if (stateInput != IN_CONT) bNextState = 1; stateInput = IN_CONT; } // change state only if there is a change in the input if(bNextState) nextState(state, stateInput); bNextState = 0; wait(0.1); } } ``` --- # Agent Instructions This documentation is published with GitBook. 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