#include //Include register definitions //Define a name and function for each button #define PLAY 0x0A #define STOP 0x0B #define PAUSE 0x0C #define PREVTRACK 0x0D #define NEXTTRACK 0x0E #define SKIPBACK 0x0F #define SKIPFORWARD 0x10 #define SHUFFLE 0x11 #define REPEAT 0x12 #define VOLUMEUP 0x13 #define VOLUMEDOWN 0x14 #define BALANCE_L 0x15 #define BALANCE_R 0x16 #define MUTE 0x17 #define RECORD 0x18 #define UNUSED 0x19 #define POWER 0x1A #define DRIVE 0x1B #define EJECT 0x1C #define ADDRESS 0x0F #define FALSE 0 #define TRUE 1 sbit RC5_DATA_OUT = P1^0; sbit RC5_MODULATED_OUT = P0^7; sbit ROW_1 = P0^2; sbit ROW_2 = P0^3; sbit ROW_3 = P0^4; sbit ROW_4 = P0^5; //Function prototypes void configure_chip(void); void scan_switches(unsigned char, unsigned char); void send_code(unsigned char); void transmit(unsigned char); unsigned char bit_mask = 0x10; //used to create a serial data stream unsigned int k = 0; //a for loop counter unsigned int count = 0; //used with the Timer1 interrupt function to get the correct data rate on the RC5 output pin (P1^0) unsigned char row = 0; void main(void) { RC5_MODULATED_OUT = FALSE; //make sure the LEDs are off, otherwise we'll burn them out // setup all the registers in the 8051 configure_chip(); RC5_DATA_OUT = FALSE; //so we don't burn the LEDs while(TRUE) //do all this forever, or until we lose power { //scan the buttons ROW_1 = TRUE; row = P1 & 0xFE; //mask out P1.0 as that is the unmodulated RC5 output scan_switches(1, row); //check P1.1 to P1.7 on column 1 // and if any of P1.1 to P1.7 are high, send associated code for that button on column 1 ROW_1 = FALSE; ROW_2 = TRUE; row = P1 & 0xFE; //mask out P1.0 as that is the unmodulated RC5 output scan_switches(2, row); //check P1.1 to P1.7 on column 2 //and if any of P1.1 to P1.7 are high, send associated code for that button on column 2 ROW_2 = FALSE; ROW_3 = TRUE; row = P1 & 0xFE; //mask out P1.0 as that is the unmodulated RC5 output scan_switches(3, row); //check P1.1 to P1.7 on column 3 //and if any of P1.1 to P1.7 are high, send associated code for that button on column 3 ROW_3 = FALSE; ROW_4 = TRUE; row = P1 & 0xFE; //mask out P1.0 as that is the unmodulated RC5 output scan_switches(4, row); //check P1.1 to P1.7 on column 4 //and if any of P1.1 to P1.7 are high, send associated code for that button on column 4 ROW_4 = FALSE; RC5_DATA_OUT = FALSE; }; } void scan_switches(unsigned char column, unsigned char row) { switch(column) { case(1): //figure out code to send to send_code() switch(row) { case(0x02): send_code(PLAY); break; case(0x04): send_code(STOP); break; case(0x08): send_code(PAUSE); break; case(0x10): send_code(RECORD); break; case(0x20): send_code(EJECT); break; case(0x40): send_code(VOLUMEUP); break; case(0x80): send_code(VOLUMEDOWN); break; } break; case(2): //figure out code to send to send_code() switch(row) { case(0x02): send_code(BALANCE_L); break; case(0x04): send_code(BALANCE_R); break; case(0x08): send_code(PREVTRACK); break; case(0x10): send_code(SHUFFLE); break; case(0x20): send_code(MUTE); break; case(0x40): send_code(NEXTTRACK); break; case(0x80): send_code(REPEAT); break; } break; case(3): //figure out code to send to send_code() switch(row) { case(0x02): send_code(DRIVE); break; case(0x04): send_code(UNUSED); break; case(0x08): send_code(POWER); break; case(0x10): send_code(0); break; case(0x20): send_code(1); break; case(0x40): send_code(2); break; case(0x80): send_code(3); break; } break; case(4): //figure out code to send to send_code() switch(row) { case(0x02): send_code(4); break; case(0x04): send_code(5); break; case(0x08): send_code(6); break; case(0x10): send_code(7); break; case(0x20): send_code(8); break; case(0x40): send_code(9); break; } break; } } // Set up the registers required for this project // Refer C8051F005 data sheet for a detailed discription of each register void configure_chip(void) { int i = 0; //Disable the WatchDog WDTCN = 0xDE; WDTCN = 0xAD; //timer 3 - counts to 278 then raises an interrupt // at 20MHz, one count is 50ns. 278 x 50 = 13.9us TCON = 0x40; TMOD = 0x20; TMR3RLH = 0xFE; //65535 - 278 TMR3RLL = 0xEA; TMR3H = TMR3RLH; TMR3L = TMR3RLL; TMR3CN = 0x06; //UART init // setup the UART for 2400, 8, N, 1 - no need to go super fast here SCON = 0x50; CKCON = 0x30; T2CON = 0x34; RCAP2H = 0xFE; RCAP2L = 0xFC; TH2 = 0xFE; TL2 = 0xFC; TI = TRUE; RI = FALSE; //port IO init XBR0 = 0x04; //UART assigned to Port0 XBR1 = 0x00; XBR2 = 0x40; //Weak pull ups enabled for Open Drain outputs PRT0CF = 0xFC; PRT1CF = 0xFF; //oscillator init OSCXCN = 0x67; for (i = 0; i < 3000; i++); // Wait 1ms for initialization while ((OSCXCN & 0x80) == FALSE); OSCICN = 0x08; //interrupts init IE = 0x80; //enable global interrupts EIE2 = 0x01; EIP2 = 0x01; } void send_code(unsigned char button) { //This routine is, basically, a parallel to serial converter //Each bit in the RC5 data to be sent is AND-ed with a Mask //if the result is 1, send a 1 out the RC5 port, otherwise send a 0 //Do this twice, once for button down //Two start bits, a "button toggle bit", the 5 bit device address (I've choosen 0x0F), then the 6 bit command //Then for the button up - the only difference is that the toggle bit has changed. //BUTTON DOWN bit_mask = 0x10; // Send two start bits transmit(TRUE); transmit(TRUE); // Send a toggle bit - 1 transmit(TRUE); // Send address - 5 bits for (k = 0; k < 5; k++) { // determine whether to put a 0 or 1 on to the DATA pin if ((ADDRESS & bit_mask) > 0) transmit(TRUE); else transmit(FALSE); // Shift bit_mask right 1 bit 0x10->0x08->0x04->0x02->0x01 bit_mask = bit_mask >> 1; } //Send button command bit_mask = 0x20; // 6 data bits, MSB first for (k = 0; k < 6; k++) { // determine whether to put a 0 or 1 on to the DATA pin if ((button & bit_mask) > 0) transmit(TRUE); else transmit(FALSE); // Shift bit_mask right 1 bit 0x20->0x10->0x08->0x04->0x02->0x01 bit_mask = bit_mask >> 1; } //BUTTON UP bit_mask = 0x10; // Send two start bits transmit(TRUE); transmit(TRUE); // Send a toggle bit - 0 transmit(FALSE); // Send address - 5 bits for (k = 0; k < 5; k++) { // determine whether to put a 0 or 1 on to the DATA pin if ((0x0F & bit_mask) > 0) transmit(TRUE); else transmit(FALSE); // Shift bit_mask right 1 bit 0x10->0x08->0x04->0x02->0x01 bit_mask = bit_mask >> 1; } //Send button command bit_mask = 0x20; // 6 data bits, MSB first for (k = 0; k < 6; k++) { // determine whether to put a 0 or 1 on to the DATA pin if ((button & bit_mask) > 0) transmit(TRUE); else transmit(FALSE); // Shift bit_mask right 1 bit 0x20->0x10->0x08->0x04->0x02->0x01 bit_mask = bit_mask >> 1; } } void transmit(unsigned char level) { //In RC5, a logic 1 is represented by the data line going low for 889us, then high for 889us // a logic 0 is represented by the data line going high for 889us, then low for 889us switch(level) { case 0: //go high for 889us then low for 889us RC5_DATA_OUT = TRUE; while(count < 63); //64 x 13.9us = 889 RC5_DATA_OUT = FALSE; while(count < 125); //(126 - 64) x 13.9us = 889 break; case 1: //go low for 889us then high for 889us RC5_DATA_OUT = FALSE; while(count < 63); RC5_DATA_OUT = TRUE; while(count < 125); break; } count = 0; } /************************************ INTERRUPT SERVICE ROUTINES **********************************************/ void Timer3_Isr (void) interrupt 14 //interrupt every 13.9uS { if (RC5_DATA_OUT == TRUE) { RC5_MODULATED_OUT = ~RC5_MODULATED_OUT; } else RC5_MODULATED_OUT = FALSE; count++; TMR3CN = 0x06; }