Chapter 12 Capturing Input. Di Jasio - Programming 32-bit Microcontrollers in C Button Inputs.

Chapter 12 Chapter 12 Capturing InputCapturing Input

Di Jasio - Programming 32-bit Microcontrollers in C

Button InputsButton Inputs


Inputs PackingInputs Packing

int readK( void){ // returns 0..F if keys pressed, 0 = none int c = 0; if ( !_RD6) // leftmost button c |= 8; if ( !_RD7) c |= 4; if ( !_RA7) c |= 2; if ( !_RD13) // rightmost button c |= 1; return c;} // readK


De-BouncingDe-Bouncingint getK( void){ // wait for a key pressed and debounce int i=0, r=0, j=0; int c; // 1. wait for a key pressed for at least .1sec do{ Delayms( 10); if ( (c = readKEY())) { if ( c>r) // if more than one button r = c; // take the new code i++; } else i=0; } while ( i<10);

// 2. wait for key released for at least .1 sec i =0; do { Delayms( 10); if ( (c = readKEY())) { if (c>r) // if more then one button

r = c; // take the new code i=0; j++; // keep counting } else i++; } while ( i<10); // 3. check if a button was pushed longer than 500ms if ( j>50) r+=0x80; // add a flag in bit 7 // 4. return code return r;} // getK


Rotary EncodersRotary Encoders


Polling ExamplePolling Example/*** Rotary.c*/// configuration bit settings, Fcy=72MHz, Fpb=36MHz#pragma config POSCMOD=XT, FNOSC=PRIPLL #pragma config FPLLIDIV=DIV_2, FPLLMUL=MUL_18, FPLLODIV=DIV_1#pragma config FPBDIV=DIV_2, FWDTEN=OFF, CP=OFF, BWP=OFF #include <p32xxxx.h>#include <explore.h>#include <LCD.h> #define ENCHA _RA9 // channel A#define ENCHB _RA10 // channel B main( void) { int i = 0; char s[16]; initLCD(); // main loop while( 1) { while( ENCHA); // detect CHA falling edge Delayms( 5); // debounce i += ENCHB ? 1 : -1; while( !ENCHA); // wait for CHA rising edge Delayms( 5); // debounce // display relative counter value clrLCD(); sprintf( s, "%d", i); putsLCD( s); } // main loop } // main


Interrupt DrivenInterrupt Driven

Rotary Encoder State Machine Diagram

Rotary Encoder State Machine Transitions Table


Interrupt Driven Example Interrupt Driven Example /*** Rotary2.c*/// configuration bit settings, Fcy=72MHz, Fpb=36MHz#pragma config POSCMOD=XT, FNOSC=PRIPLL #pragma config FPLLIDIV=DIV_2, FPLLMUL=MUL_18, FPLLODIV=DIV_1#pragma config FPBDIV=DIV_2, FWDTEN=OFF, CP=OFF, BWP=OFF #include <p32xxxx.h>#include <plib.h>#include <explore.h>#include <LCD.h> #define ENCHA _RA9 // encoder channel A#define ENCHB _RA10 // encoder channel B#define TPMS (FPB/1000) // PB clock ticks per ms // state machine definitions#define R_IDLE 0 #define R_DETECT 1 volatile int RCount;char RState;

void initR( void){ // init state machine RCount = 0; // init counter RState = 0; // init state machine // init Timer2 T2CON = 0x8020; // enable Timer2, Fpb/4 PR2 = 5*TPMS/4; // 5ms period mT2SetIntPriority( 1); mT2ClearIntFlag(); mT2IntEnable( 1);} // init R


Interrupt Service RoutineInterrupt Service Routinevoid __ISR( _TIMER_2_VECTOR, ipl1) T2Interrupt( void){ static char d; switch ( RState) { default: case R_IDLE: // waiting for CHA rise if ( ! ENCHA) { RState = R_DETECT; if ( ! ENCHB) d = -1; } else d = 1; break; case R_DETECT: // waitin for CHA fall if ( ENCHA) { RState = R_IDLE; RCount += d; } break; } // switch mT2ClearIntFlag(); } // T2 Interrupt


Example (cont.)Example (cont.)main( void) { int i = 0; char s[16]; initEX16(); // init and enable interrupts initLCD(); // init LCD module initR(); // init Rotary Encoder // main loop while( 1) { Delayms( 100); // place holder for a complex app. clrLCD(); sprintf( s, "RCount = %d", RCount); putsLCD( s); } // main loop } // main


KeyboardsKeyboardsPhysical Interface (5-pin DIN)

Physical Interface (6-pin mini-DIN)


PS2 Communication ProtocolPS2 Communication Protocol

Host Communication Waveform


Input Capture ModulesInput Capture Modules

Figure 15-1 (DS61143)


PS/2 Bit TimingPS/2 Bit Timing


IC State MachineIC State Machine


IC ISRIC ISRvoid __ISR( _INPUT_CAPTURE_1_VECTOR, ipl1) IC1Interrupt( void){ // input capture interrupt service routine int d; // 1. reset timer on every edge TMR2 = 0; switch( PS2State){ default: case PS2START: if ( ! PS2DAT) // verify start bit { KCount = 8; // init bit counter KParity = 0; // init parity check PR2 = TMAX; // init timer period T2CON = 0x8000; // enable TMR2, 1:1 PS2State = PS2BIT; } break; case PS2BIT: KBDBuf >>=1; // shift in data bit if ( PS2DAT) KBDBuf += 0x80; KParity ^= KBDBuf; // update parity if ( --KCount == 0) // if all bit read, move on PS2State = PS2PARITY; break; case PS2PARITY: if ( PS2DAT) // verify parity bit KParity ^= 0x80; if ( KParity & 0x80) // if parity odd, continue PS2State = PS2STOP; else PS2State = PS2START; break;

case PS2STOP: if ( PS2DAT) // verify stop bit { KBDCode = KBDBuf; // save code in mail box KBDReady = 1; // set flag, code available T2CON = 0; // stop the timer } PS2State = PS2START; break; } // switch state machine // clear interrupt flag d = IC1BUF; // discard capture mIC1ClearIntFlag(); } // IC1 Interrupt


Using Stimulus FilesUsing Stimulus Files


Test ProgramTest Program/* ** PS2ICTest.c***/// configuration bit settings, Fcy=72MHz, Fpb=36MHz#pragma config POSCMOD=XT, FNOSC=PRIPLL #pragma config FPLLIDIV=DIV_2, FPLLMUL=MUL_18, FPLLODIV=DIV_1#pragma config FPBDIV=DIV_2, FWDTEN=OFF, CP=OFF, BWP=OFF #include <p32xxxx.h>#include <explore.h>#include "PS2IC.h" main(){ int Key; initEX16(); // init and enable interrupts initKBD(); // initialization routine while ( 1) { if ( KBDReady) // wait for the flag { Key = KBDCode; // fetch the key code KBDReady = 0; // clear the flag } } // main loop} //main


Simulator ProfilerSimulator Profiler

Chapter 12 Capturing Input. Di Jasio - Programming 32-bit Microcontrollers in C Button Inputs.

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