File content as of revision 0:ad1dcc41c893:

// My AM/FM Radio, Lab 3 Main
// Jammie Proctor
// 03/02/2013

#include "mbed.h"
#include "TextLCD.h"

I2C radio(p28, p27);                        // sda, scl
TextLCD lcd(p15, p16, p17, p18, p19, p20);  // rs, e, d4-d7
DigitalIn AM_FM(p22);                       // Radio mode AM/FM
DigitalIn station(p23);                     // Station seek/scan
DigitalOut reset(p21);                      // Radio reset
DigitalOut lock(LED1);                      // Station active
PwmOut rclock(p24);                         // Rclock generation

//====================================== Global Variables =============================================
const int write_addr=0x22;                          
int fm_pwr_up[3]={0x01, 0x00, 0x05};                    // FM power-up command
int am_pwr_up[3]={0x01, 0x01, 0x05};                    // AM power-up command
int fm_station[4]={0x20, 0x00, 0x22, 0x60};             // Set FM station
int am_station[6]={0x40, 0x00, 0x02, 0x17, 0x00, 0x00}; // Set AM station
float lcd_station=88.0;
int reg_station=8800, reg_am_station=535, i=0, Response, ack=0, pwr_down=0x11, tune=0x31;
int* p_pwr_down = &pwr_down;
int* p_tune = &tune;
bool last_mode=0;

//===================================== Support Functions =============================================
void SendCommand(int* array, int length) {  /* Send Command to Si4735 */
    radio.start();
    ack=radio.write(write_addr);
    for(i=0; i<length; i++) ack=radio.write(array[i]);
    Response=radio.read(ack);
    radio.stop();
    wait(.2);
}
    
void Reset(void) {                          /* Reset AM/FM Radio */
    reset=0;
    wait(.2);
    reset=1;
    wait(.2);
}

void AM_Restart(void) {                     /* Reinitialize AM receiver */                 
    SendCommand(p_tune, 1);                         // Disable carrier
    wait(.2);
    SendCommand(p_pwr_down, 1);                     // Power down sequence
    wait(.2); 
    Reset();
    SendCommand(am_pwr_up, 3);                      // Launch AM 
    SendCommand(am_station, 6);                     // Play current AM station
}

void FM_Restart(void) {                     /* Reinitialize FM receiver */                          
    SendCommand(p_tune, 1);                         // Disable carrier
    wait(.2);
    SendCommand(p_pwr_down, 1);                     // Power down sequence
    wait(.2); 
    Reset();
    SendCommand(fm_pwr_up, 3);                      // Launch FM
    SendCommand(fm_station, 4);                     // Play current FM station
}
//================================================ Main Code =======================================================
int main() {
    AM_FM.mode(PullUp);
    station.mode(PullUp);
    lock=0;
    rclock.period(.000030518);                  // Set rclock oscillator to 32.768kHz
    rclock=0.5;                                 // 50% Duty Cycle for rclock
    radio.frequency(100000);                    // I^2C frequency setting 100kHz
    Reset();                                   
    SendCommand(fm_pwr_up, 3);                  // Initialize FM
    SendCommand(fm_station, 4);                 // Play default fm station
    last_mode=AM_FM;
        
    while(1) {
        if(AM_FM) {                                 // FM selected (SW1 in the off position)
            if(AM_FM!=last_mode) FM_Restart();      
            last_mode=AM_FM;
            if(!station) {                          // SW2 pressed? Go to next station
                lock=0;
                while(!station);
                if(reg_station<10800) reg_station+=10;
                else reg_station=8800;
                lcd_station=reg_station/100.0;
                fm_station[3]=reg_station&0x00FF;
                fm_station[2]=reg_station>>8;
                SendCommand(fm_station, 4);          
                lock=1;       
            }
            lcd.printf("Station:\n %3.1fMHz FM", lcd_station);
            wait(.1);
            lcd.cls();
        }
        else {                                              // AM selected (SW1 in the on position)
            if(AM_FM!=last_mode) AM_Restart();
            last_mode=AM_FM;
            if(!station) {                                  // SW2 pressed? Go to next station
                lock=0;
                while(!station);
                if(reg_am_station<1700) reg_am_station+=5;
                else reg_am_station=530;
                am_station[3]=reg_am_station&0x00FF;
                am_station[2]=reg_am_station>>8;
                SendCommand(am_station, 6);                 
                lock=1;       
            }
            lcd.printf("Station:\n %ukHz AM", reg_am_station);
            wait(.1);
            lcd.cls();
        }
    }
}