main.cpp

// Georgia Tech ECE 4180
// Design Project for mbed
// Brett Berry and Brett Wilson

#include "mbed.h"
#include "mpr121.h"
#include "TextLCD.h"
#include "Si4735.h"

// Create the interrupt receiver object on pin 8
InterruptIn interrupt(p8);
// Setup the i2c bus on pins 9 and 10
I2C i2c(p9, p10);
// Setup the Mpr121:
// constructor(i2c object, i2c address of the mpr121)
Mpr121 mpr121(&i2c, Mpr121::ADD_VSS);

// constructor for the TextLCD display
TextLCD lcd(p21, p22, p25, p26, p29, p30); // rs, e, d4-d7

// constructor for the Si4735 AM/FM radio
// Si4735(PinName sda, PinName scl, PinName RST_)
Si4735 radio(p28, p27, p16);

DigitalOut led(LED1);
DigitalOut led2(LED2);

// Initiallize USB serial connection for debugging
Serial pc(USBTX, USBRX); // tx, rx

// Initialize variables
int station = 0; // stores the calculation for the stn freq being entered
int next_stn = 0; // buffer for the station freq to be sent to the radio
bool stn_ready = false; // flag raised to send frequency to radio
bool rst_lcd = false; // flag to reset the LCD display and station entry variables
bool test_flag = false; // test flag for other functions not used in main function
int count = 0; // counter for the number of keys pressed to prevent overflow
float temp = 997; // temporary float for printing frequency to LCD display
int response; // store the response from the getFrequency method

// Key hit/release interrupt routine
// Warning: Keep code in interrupt to a minimum to prevent crash
void fallInterrupt() {
  int key_code=0;
  int i=0;
  int value = mpr121.read(0x00);
  value += mpr121.read(0x01)<<8;
  // LED demo mod
  // puts key number out to LEDs for demo
  // scans mpr121 register bits in order to determine which key was pressed
  for (i=0; i<12; i++) {
    if (((value>>i)&0x01)==1) {
        key_code = i + 1; // Add one to key_code to offset key release signal (0)
    }
  }
  if ((key_code < 11) && (key_code>0)) { // add number to station frequency
    station = 10*station + key_code - 1;
    count++;
  }
  else if ((key_code == 11) && (count > 2)) { // enter station and send to radio
    // raise station ready flag and copy station into temporary variable
    next_stn = 10 * station;
    stn_ready = true;
    station = 0;
  }
  else if (key_code == 12){ // reset the lcd display and station calculation
    // raise reset LCD flag
    led2 = !led2;
    rst_lcd = true;
    test_flag = true;
  }
}

int main() {
    // define the interupt routine for the keypad
    interrupt.fall(&fallInterrupt);
    interrupt.mode(PullUp);
    
    led = 1;
    led2 = 0;
    
    // Display the frequency info for the default frequency
    // 99.70 MHz chosen as default since it's the strongest local frequency
    lcd.cls();
    lcd.printf("Current Station\n99.70 MHz FM\n");
    
    // Power up the radio and initialize to default frequency
    radio.begin(FM);
        
    while(1) {
        
        if (stn_ready) { // Next station ready to be sent to radio
            if ((next_stn >= 8750) && (next_stn <= 10790)) { // Screen for valid FM frequencies
                radio.tuneFrequency(next_stn); // Send station to radio
                // tuneFrequency command sends frequency in 10s of KHz
                temp = float(next_stn)/100.0; // Calculate freq float in MHz
                lcd.cls(); // clear LCD screen
                // display new station frequency information on LCD
                lcd.printf("Current Station\n%3.2f MHz FM\n", temp);
                stn_ready = false; // reset stn_ready flag
                count = 0; // reset key press count
            }
            else if (next_stn < 8750) { // Frequency lower than minimum frequency detected
                lcd.cls();
                lcd.printf("Station entry\nunderflow->reset"); // display error message
                count = 0;
                station = 0;
                stn_ready = false;
            }
            else { // Frequency higher than maximum frequency detected
                lcd.cls();
                lcd.printf("Station entry\noverflow->reset\n"); // display error message
                count = 0;
                station = 0;
                stn_ready = false;
            }
        }
        if (count > 4) { // too many keys pressed on the keypad
            lcd.cls();
            lcd.printf("Station entry\noverflow->reset\n"); // display error message
            count = 0;
            station = 0;
        }
        if (rst_lcd) { // flag for resetting LCD
            lcd.cls();
            // Display last valid station entry
            lcd.printf("Current Station\n%3.2f MHz FM\n", temp);
            count = 0;
            station = 0;
            rst_lcd = false;
        }
        if (test_flag) { // flag for testing other methods
            response = radio.getFrequency();
            pc.printf("Current Frequency: %d\n\r", response);
            //radio.seekUp();
            //radio.seekDown();
            //radio.mute();
            //radio.unmute();
            test_flag = false;
        }
        led = !led;
        wait(.2);    
    }
}