老外写的用MCU控制IPOD的代码

/* ECE 476 Final Project * Austin S. Lu & Albert Ren * asl45 awr8 */ #include <mega32.h> #include <stdio.h> #include <stdlib.h> //for ltoa #include <delay.h> #asm .equ __lcd_port=0x15 #endasm #include <lcd.h> //Bruce's definitions #define begin { #define end } //Define the states for the state machine #define Command 0 #define DecodeCommand 1 #define Send 2 #define button_release 3 #define hold 4 #define Receive 5 int state = 0; //Define the commands we support //MODE 2 iPod Remote Functions #define play 0x01 #define volup 0x02 #define voldown 0x04 #define skipfwd 0x08 #define skipback 0x10 #define menu 0x40 #define select 0x80 //MODE 4 Advanced Remote #define type 0x12 #define name 0x14 #define current 0x1e #define title 0x20 #define artist 0x22 #define album 0x24 //MODE 4 Send Commands #define Switch 0 #define GetTrack 1 #define UseTrack 2 #define SwitchtoMode2 3 #define SendPlay 4 //Information on the Apple Accessory Protocol can be found at // http://ipodlinux.org/Apple_Accessory_Protocol //Here are some variables that we'll need char mstime = 0; char header1 = 0xff; char header2 = 0x55; char length; char mode=0x02; char command[2]; int checksum; int index = 0; int debouncecounter = 0; char lastpress = 0; char press = 0; int timeout = 0; unsigned long currentsong; int param_length = 0; //Here are the flags we're using char validcommand = 0; char commandtype = 0; char stopflag = 0; char releaseflag = 0; char transmitdone_flag = 0; char mode4flag = 0; unsigned char switchmode[16] = {0xff, 0x55, 0x03, 0x00, 0x01, 0x04, 0xF8, 0x05, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}; unsigned char switchback[16] = {0xff, 0x55, 0x03, 0x00, 0x01, 0x02, 0xFA, 0x05, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}; unsigned char currenttrackcommand[16] = {0xff, 0x55, 0x03, 0x04, 0x00, 0x1E, 0xDB, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}; int tempchecksum; unsigned char t_buffer_temp[16]; //For LCD displays unsigned char lcdbuffer[50]; unsigned int lcdbufferlength = 16; unsigned int lcdstart = 0; int lcdtime = 0; char hold_timer = 0; int timeoutcounter = 0; int failurecount = 0; int mode4sequence = 0; //variables we use for transmitting unsigned char t_index; //current string index unsigned char t_buffer[16]; //output string unsigned char t_ready; //flag for transmit done unsigned char t_char; //current character //RXC ISR variables unsigned char r_index=0; //current string index unsigned char r_buffer[128]; //input string unsigned char r_ready; //flag for receive done unsigned char r_char; //current character unsigned char r_checksum; //received checksum unsigned char prev_char = 0; unsigned char start_checksum = 0; unsigned char r_length = 0xF5; //Functions we use void initialize(void); void puts_int(void); void buttons (void); void gets_int(void); void lcd_scroll(void); //timer 0 overflow ISR interrupt [TIM0_COMP] void timer0_overflow(void) begin mstime++; lcdtime ++; end //UART xmit-empty ISR //TRANSMITS LSB FIRST (Little Endian is stupid!) //http://en.wikipedia.org/wiki/Serial_port interrupt [USART_DRE] void uart_send(void) { t_index++; t_char = t_buffer[t_index]; if(t_char == (char)checksum){//at this point, we know what the end is UDR = t_char; stopflag = 1; stopflag = 0; UCSRB.5=0; //kill isr t_ready=1; //transmit done checksum = 0; } else {UDR = t_char;} //send the char } //UART character-ready ISR interrupt [USART_RXC] void uart_rec(void) begin r_char=UDR; //get a char //build the input string //iPod takes the form of 0xFF 0x55 Data Checksum //We are assuming idle high, so we should check for 0x55 instead if((r_char == (char)(r_checksum & 0xff)) && ((r_index-3)==r_length)) { r_ready=1; //signal cmd processor UCSRB.7=0; //stop rec ISR start_checksum = 0; } if(start_checksum == 1) { r_checksum = r_checksum - r_char; } if(r_char == 0x55 && prev_char == 0xff) { start_checksum = 1; r_checksum = 0x100; } r_buffer[r_index]=r_char; if(r_index == 2) //Make the length so! r_length = r_buffer[r_index]; r_index++; prev_char = r_char; end void main(void) begin int k, temp, ReturnToSender; unsigned char songnumber; //State machine updates every ms for now initialize(); while(1) begin if(lcdtime >= 300) { lcdtime = 0; lcd_scroll(); } if(mstime) begin buttons(); mstime = 0; switch (state) begin case(Command): //check if there's a command. If so, we will decode it mode4sequence = Switch; timeoutcounter = 0; failurecount = 0; if(validcommand == 1) begin validcommand = 0; state = DecodeCommand; end if((releaseflag == 1) && (validcommand == 0) && (mode == 0x02)) //the button was released begin releaseflag = 0; state = button_release; end break; case(DecodeCommand): //We must decode the command! If statements galore! t_buffer[0] = header1; //0xff t_buffer[1] = header2; //0x55 if((mode == 0x02) || (commandtype == current)) { length = 0x03; } else begin length = 7; //Otherwise length is 7 bytes, cause it's a mode 4 command end t_buffer[2] = length; t_buffer[3] = mode; if(mode == 0x04) { mode4flag = 1; } t_buffer[4] = 0x00; //Beginning of command if(commandtype == play) t_buffer[5] = play; if(commandtype == volup) t_buffer[5] = volup; if(commandtype == voldown) t_buffer[5] = voldown; if(commandtype == skipfwd) t_buffer[5] = skipfwd; if(commandtype == skipback) t_buffer[5] = skipback; if(commandtype == album) t_buffer[5] = album; if(commandtype == title) t_buffer[5] = title; if (commandtype == artist) t_buffer[5] = artist; if((mode == 0x04) && (commandtype != current)) //We need to send ipod the current song begin t_buffer[6] = (currentsong >> 24) & 0xff ; //& with 0xFF cause we're cautious people! t_buffer[7] = (currentsong >> 16) & 0xff; t_buffer[8] = (currentsong >> 8) & 0xff; t_buffer[9] = currentsong & 0xff; param_length = 4; //Mode 4 and Mode 2 have different lengths end for (index = 2; index < 6 + param_length; index ++) { //for checksum checksum = checksum + t_buffer[index]; } checksum = (0x100 - checksum & 0xff); t_buffer[6+param_length] = (char) checksum & 0xff; //as a char */ param_length = 0; //We always reset to Mode 2 commands state = Send; break; case(Send): stopflag = 0; timeoutcounter = 0;