Cleaned up indentation and coding style ...

[rctxduino] / source / RCTXDuino / RCTXDuino.pde

// No longer using HD44780-comaptible display,
// Moving to a brand new world of dot-matrix display tech!
// Using LCD library from http://code.google.com/p/pcd8544/
#include <PCD8544.h>

#include <TimerOne.h>
#include <EEPROM.h>

// Undefine this whenever a "release" or "flight-test" build is made.
// Defining DEBUG sets some crazy values for things like battery warning,
// and includes a whole bunch of debugging-related code ...
#define DEBUG 1

#define MAX_INPUTS 8

// Update this _every_ time a change in datastructures that
// can/will ber written to EEPROM is done. EEPROM data is
// read/written torectly into/from the data structures using
// pointers, so every time a data-set change occurs, the EEPROM
// format changes as well..
#define EEPROM_VERSION 7

// Some data is stored in fixed locations, e.g.:
//  * The EEPROM version number for the stored data (loc 0)
//  * The selected model configuration number (loc 1)
//  * (add any other fixed-loc's here for doc-purpose)
// This means that any pointer-math-operations need a BASE
// adress to start calc'ing from. This is defined as:
#define EE_BASE_ADDR 10 

// Having to repeat tedious base-address-calculations for the
// start of model data should be unnessecary. Plus, updating
// what data is stored before the models will mean that each
// of those calculations must be updated. A better approach is
// to define the calculation in a define!
// NOTE: If new data is added in front of the model data,
// this define must be updated!
#define EE_MDL_BASE_ADDR (EE_BASE_ADDR+(sizeof(input_cal_t)+ 10))

// Just as a safety-precaution, update/change this if a chip with
// a different internal EEPROM size is used. Atmega328p has 1024 bytes.
#define INT_EEPROM_SIZE 1024

#define MAX_MODELS 4 // Nice and random number..


// --------------- ADC related stuffs.... --------------------

struct input_cal_t // Struct type for input calibration values
{
        int min[MAX_INPUTS];
        int max[MAX_INPUTS];
        int center[MAX_INPUTS];
} ;
input_cal_t input_cal;

struct model_t
{
        int channels; // How many channels should PPM generate for this model ...
        float stick[8]; // The (potentially recalc'ed) value of stick/input channel.
        int raw[8];
        boolean rev[8];
        int dr[8];        // The Dual-rate array uses magic numbers :P
        /*      dr[0] = Input channel #1 of 2 for D/R switch #1. 0 means off, 1-4 valid values.
                dr[1] = Input channel #2 of 2 for D/R switch #1. 0 means off, 1-4 valid values.
                dr[2] = Input channel #1 of 2 for D/R switch #2. 0 means off, 1-4 valid values.
                dr[3] = Input channel #2 of 2 for D/R switch #2. 0 means off, 1-4 valid values.
                dr[4] = D/R value for switch # 1 LOW(off). Value -100 to 100 in steps of 5.
                dr[5] = D/R value for switch # 1 HIGH(on). Value -100 to 100 in steps of 5.
                dr[6] = D/R value for switch # 1 LOW(off). Value -100 to 100 in steps of 5.
                dr[7] = D/R value for switch # 1 HIGH(on). Value -100 to 100 in steps of 5. 
        */
};
volatile model_t model;
unsigned char current_model; // Using uchar to spend a single byte of mem..

// ----------------- Display related stuffs --------------------
PCD8544 lcd( 8,  9,   10, 11,    12);
// Param:   sclk, sdin, dc, reset, sce

// ----------------- PPM related stuffs ------------------------
// The PPM generation is handled by Timer0 interrupts, and needs
// all modifiable variables to be global and volatile...

volatile long sum = 0;                  // Frame-time spent so far
volatile int cchannel = 0;              // Current channnel
volatile bool do_channel = true;        // Is next operation a channel or a separator


// All time values in usecs
// TODO:
// The timing here (and/or in the ISR) needs to be tweaked to provide valid
// RC PPM signals accepted by standard RC RX'es and the Microcopter...

#define framelength  21000              // Max length of frame
#define seplength      300              // Lenght of a channel separator
#define chmax         1600              // Max lenght of channel pulse
#define chmin          495              // Min length of channel
#define chwidht  (chmax - chmin)// Useable time of channel pulse

// ----------------- Menu/IU related stuffs --------------------

// Keys/buttons/switches for UI use, including dual-rate/expo
// are digital inputs connected to a 4051 multiplexer, giving
// 8 inputs on a single input pin.
#define KEY_UP    0
#define KEY_DOWN  1
#define KEY_RIGHT 2
#define KEY_LEFT  3
#define KEY_INC   4
#define KEY_DEC   5
#define KEY_DR1   6
#define KEY_DR2   7

// Voltage sense pin is connected to a 1/3'd voltage divider.
#define BATTERY_CONV (10 * 3 * (5.0f/1024.0f))

#ifdef DEBUG
// The following values are for DEBUGGING ONLY!!
#define BATTERY_LOW 92
#define BATTERY_CRITICAL 0
#else
#define BATTERY_LOW 92
#define BATTERY_CRITICAL 92
#endif

enum {
        VALUES,
        BATTERY,
        TIMER,
        CURMODEL,
        MENU
} 
displaystate;

enum {
        TOP,
        INVERTS,
        DUALRATES,
        EXPOS, // Some radios have "drawn curves", i.e. loopup tables stored in external EEPROM ...
        DEBUG_DUMP,
        SAVE
} 
menu_mainstate;
int menu_substate;

boolean keys[8];
boolean prev_keys[8];

int battery_val;

// The display/UI is handled only when more
// than UI_INTERVAL milliecs has passed since last...
#define UI_INTERVAL 250
unsigned long last = 0;

struct clock_timer_t 
{
        unsigned long start;
        unsigned long init;
        unsigned long value;
        boolean running;
} clock_timer;

#ifdef DEBUG
// -----------------  DEBUG-STUFF --------------------
unsigned long prev_loop_time;
unsigned long avg_loop_time;
unsigned long t;
#endif

// ---------- CODE! -----------------------------------

// ---------- Arduino SETUP code ----------------------
void setup(){
        pinMode(13, OUTPUT);   // led

        pinMode(2, OUTPUT);    // s0
        pinMode(3, OUTPUT);    // s1
        pinMode(4, OUTPUT);    // s2
        pinMode(5, OUTPUT);    // e

        lcd.begin(84, 48);
        lcd.print("Starting....");

#ifdef DEBUG  
        Serial.begin(9600);
        Serial.println("Starting....");
#endif
  
        delay(500);

        model_defaults();
        read_settings();

        displaystate = VALUES;
  
        // Arduino believes all pins on Port C are Analog.
        // In reality they are tri-purpose; ADC, Digital, Digital Interrupts
        // Unfortunately the interrupt mode is unusable in this scenario, but digital I/O works :P
        pinMode(A2, INPUT); 
        digitalWrite(A2, HIGH);
        scan_keys();
        if ( !keys[KEY_UP])
                calibrate();
  
#ifdef DEBUG
        // Debugging: how long does the main loop take on avg...  
        t = micros();
        avg_loop_time = t;
        prev_loop_time = t;    
#endif

        // Initializing the stopwatch timer/clock values...
        clock_timer = (clock_timer_t){0, 0, 0, false};

        pinMode(A5, OUTPUT);  // PPM output pin  
        do_channel = false;
        set_timer( seplength );
        Timer1.initialize(framelength);
        Timer1.attachInterrupt(ISR_timer);  

        lcd.clear();
}

void model_defaults( void )
{
        // This function provides default values for model data
        // that is not a result of stick input, or in other words:
        // provides defautls for all user-configurable model options.

        // Remember to update this when a new option/element is added
        // to the model_t struct (preferably before implementing the
        // menu code that sets those options ...)

        // This is used when a user wants a new, blank model, a reset
        // of a configured model, and (most important) when EEPROM
        // data format changes.
        // NOTE: This means that stored model conficuration is reset
        // to defaults when the EEPROM version/format changes.
        model.channels = 8;
        model.rev[0] = model.rev[1] = model.rev[2] = model.rev[3] = 
        model.rev[4] = model.rev[5] = model.rev[6] = model.rev[7] = false;
        model.dr[0] = model.dr[1] = model.dr[2] = model.dr[3] = 0;
        model.dr[4] = model.dr[5] = model.dr[6] = model.dr[7] = 100;
}

// ---------- Arduino main loop -----------------------
void loop ()
{  
        process_inputs();

        // Wasting a full I/O pin on battery status monitoring!
        battery_val = analogRead(1) * BATTERY_CONV;
        if ( battery_val < BATTERY_LOW ) 
                digitalWrite(13, 1); // Simulate alarm :P

        if ( battery_val < BATTERY_CRITICAL )
                displaystate = BATTERY;

        if ( millis() - last > UI_INTERVAL ) 
        { 
                last = millis(); 
                ui_handler(); 
        }
  
#ifdef DEBUG
        if ( displaystate != MENU )
        {
                // Debugging: how long does the main loop take on avg,
                // when not handling the UI...
                t = micros();
                avg_loop_time = ( t - prev_loop_time + avg_loop_time ) / 2;
                prev_loop_time = t;    
        }
#endif

        // Whoa! Slow down partner! Let everything settle down before proceeding.
        delay(5);
}

// ----- Simple support functions used by more complex functions ----

void set_ppm_output( bool state )
{
        digitalWrite(A5, state); // Hard coded PPM output
}

void set_timer(long time)
{
        Timer1.detachInterrupt();
        Timer1.attachInterrupt(ISR_timer, time);  
}

boolean check_key( int key)
{
        return ( !keys[key] && prev_keys[key] );
}

void mplx_select(int pin)
{
        digitalWrite(5, 1);
        delayMicroseconds(24);

        digitalWrite(2, bitRead(pin,0));  // Arduino alias for non-modifying bitshift operation
        digitalWrite(3, bitRead(pin,1));  // us used to extract individual bits from the int (0..7)
        digitalWrite(4, bitRead(pin,2));  // Select the appropriate input by setting s1,s2,s3 and e
        digitalWrite(5, 0);               // on the 4051 multiplexer.

        // May need to slow the following read down to be able to
        // get fully reliable values from the 4051 multiplex.
        delayMicroseconds(24);

}

// ----- "Complex" functions follow ---------------------------------

void calibrate()
{
        int i, adc_in;
        int num_calibrations = 200;

        lcd.clear();
        lcd.print("Move controls to");
        lcd.setCursor(0,1);
        lcd.print("their extremes..");
        Serial.print("Calibration. Move all controls to their extremes.");

        for (i=0; i<MAX_INPUTS; i++)
        {
                input_cal.min[i] = 1024;
                input_cal.center[i] = 512;
                input_cal.max[i] = 0;
        }

        while ( num_calibrations-- )
        {
                for (i=0; i<MAX_INPUTS; i++) 
                {
                        mplx_select(i);
                        adc_in = analogRead(0);

                        // Naive min/max calibration
                        if ( adc_in < input_cal.min[i] )
                                input_cal.min[i] = adc_in;

                        if ( adc_in > input_cal.max[i] )
                                input_cal.max[i] = adc_in;

                        delay(10);
                }
        }

        // TODO: WILL need to do center-point calibration after min-max...

        lcd.clear();
        lcd.print("Saving to EEPROM");
        write_calibration();
        lcd.setCursor(0 , 1);
        lcd.print("Done calibrating");

        Serial.print("Done calibrating");
        delay(2000);  
}

void write_calibration(void)
{
        int i;
        unsigned char v;
        const byte *p;

        // Set p to be a pointer to the start of the input calibration struct.
        p = (const byte*)(const void*)&input_cal;

        // Iterate through the bytes of the struct...
        for (i = 0; i < sizeof(input_cal_t); i++)
        {
                // Get a byte of data from the struct...
                v = (unsigned char) *p;
                // write it to EEPROM
                EEPROM.write( EE_BASE_ADDR + i, v);
                // and move the pointer to the next byte in the struct.
                *p++;
        }
}

void read_settings(void)
{
        int i;
        unsigned char v;
        byte *p;

        v = EEPROM.read(0);
        if ( v != EEPROM_VERSION )
        {
                // All models have been reset. Set the current model to 0
                current_model = 0;
                EEPROM.write(1, current_model);

                calibrate();
                model_defaults();
                // The following does not yet work...
                for ( i = 0; i < MAX_MODELS; i++)
                        write_model_settings(i);


                // After saving calibration data and model defaults,
                // update the saved version-identifier to the current ver.
                EEPROM.write(0, EEPROM_VERSION);
        }

        // Read calibration values from EEPROM.
        // This uses simple pointer-arithmetic and byte-by-byte
        // to put bytes read from EEPROM to the data-struct.
        p = (byte*)(void*)&input_cal;
        for (i = 0; i < sizeof(input_cal_t); i++)
                *p++ = EEPROM.read( EE_BASE_ADDR + i);

        // Get the previously selected model from EEPROM.
        current_model = EEPROM.read(1);
        read_model_settings( current_model );
}

void read_model_settings(unsigned char mod_no)
{
        int model_address;
        int i;
        unsigned char v;
        byte *p;

        // Calculate the EEPROM start adress for the given model (mod_no)
        model_address = EE_MDL_BASE_ADDR + (mod_no * sizeof(model_t));

        // Do not try to write the model to EEPROM if it won't fit.
        if ( INT_EEPROM_SIZE < (model_address + sizeof(model_t)) )
        {
                lcd.clear();
                lcd.print("Aborting READ");
                lcd.setCursor(0 , 1);
                lcd.print("Invalid location");
                delay(2000);  
                return;
        }
  
        lcd.clear();
        lcd.print("Reading model ");
        lcd.print( (int)mod_no );

        // Pointer to the start of the model_t data struct,
        // used for byte-by-byte reading of data...
        p = (byte*)(void*)&model;
        for (i = 0; i < sizeof(model_t); i++)
                *p++ = EEPROM.read( model_address++ );

#ifdef DEBUG
        serial_dump_model();
#endif

        lcd.setCursor(0 , 1);
        lcd.print("... Loaded.");
        delay(1000);    
}

void write_model_settings(unsigned char mod_no)
{
        int model_address;
        int i;
        unsigned char v;
        byte *p;

        // Calculate the EEPROM start adress for the given model (mod_no)
        model_address = EE_MDL_BASE_ADDR + (mod_no * sizeof(model_t));

        // Do not try to write the model to EEPROM if it won't fit.
        if ( INT_EEPROM_SIZE < (model_address + sizeof(model_t)) )
        {
                lcd.clear();
                lcd.print("Aborting SAVE");
                lcd.setCursor(0 , 1);
                lcd.print("No room for data");
                delay(2000);  
                return;
        }
  
        lcd.clear();
        lcd.print("Saving model ");
        lcd.print( (int)mod_no);
  
        // Pointer to the start of the model_t data struct,
        // used for byte-by-byte reading of data...
        p = (byte*)(void*)&model;

        // Write/serialize the model data struct to EEPROM...
        for (i = 0; i < sizeof(model_t); i++)
                EEPROM.write( model_address++, *p++);
                
        lcd.setCursor(0 , 1);
        lcd.print(".. done saving.");
        delay(200);    
}

#ifdef DEBUG
void serial_dump_model ( void )
{
        int i;
        int model_address;
        // Calculate the EEPROM start adress for the given model (mod_no)
        model_address = EE_MDL_BASE_ADDR + (current_model * sizeof(model_t));
        Serial.print("Current model:    ");
        Serial.println( (int)current_model );
        Serial.print("Models base addr: ");
        Serial.println( EE_MDL_BASE_ADDR );
        Serial.print("Model no:         ");
        Serial.println( current_model, 10 );
        Serial.print("Size of struct:   ");
        Serial.println( sizeof( model_t) );
        Serial.print("Model address:    ");
        Serial.println( model_address );
        Serial.print("End of model:     ");
        Serial.println( model_address + sizeof(model_t) );

        Serial.println();

        Serial.print("Channel reversions: ");
        for ( i = 0; i<8; i++)
        {
                Serial.print(i);
                Serial.print("=");
                Serial.print(model.rev[i], 10);
                Serial.print(" ");
        }
        Serial.println();

        Serial.print("DR1 inp 0: ");
        Serial.println(model.dr[0]);
        Serial.print("DR1 inp 1: ");
        Serial.println(model.dr[1]);
        Serial.print("DR1 LO val: ");
        Serial.println(model.dr[4]);
        Serial.print("DR1 HI val: ");
        Serial.println(model.dr[5]);
        Serial.print("DR2 inp 0: ");
        Serial.println(model.dr[2]);
        Serial.print("DR2 inp 1: ");
        Serial.println(model.dr[3]);
        Serial.print("DR2 LO val: ");
        Serial.println(model.dr[6]);
        Serial.print("DR2 HI val: ");
        Serial.println(model.dr[7]);
  
        for (i=0; i<MAX_INPUTS; i++) 
        {
                Serial.print("Input #");
                Serial.print(i);
                Serial.print(" pct: ");
                Serial.print(model.stick[i]);
                Serial.print(" min: ");
                Serial.print(input_cal.min[i]);
                Serial.print(" max: ");
                Serial.print(input_cal.max[i]);
                Serial.println();
        }  
}
#endif

void scan_keys ( void )
{
        boolean key_in;

        // To get more inputs, another 4051 analog multiplexer is used,
        // but this time it is used for digital inputs. 8 digital inputs
        // on one input line, as long as proper debouncing and filtering
        // is done in hardware :P
        for (int i=0; i<=7; i++)
        {
                // To be able to detect that a key has changed state, preserve the previous..
                prev_keys[i] = keys[i];

                // Select and read input.
                mplx_select(i);
                keys[i] = digitalRead(A2);
                delay(2);
        }
}


void process_inputs(void )
{
        int current_input, adc_in, fact;
        float min, max;

        for (current_input=0; current_input<MAX_INPUTS; current_input++) 
        {

                mplx_select(current_input);
                adc_in = analogRead(0);

                model.raw[current_input] = adc_in;
                // New format on stick values
                // The calculations happen around the center point, the values
                // need to arrive at 0...100 of the range "center-to-edge",
                // and must end up as negative on the ... negative side of center.
                
                if ( adc_in < input_cal.center[current_input] )
                {
                                // The stick is on the negative side, so the range is
                                // from the lowest possible value to center, and we must
                                // make this a negative percentage value.
                                max = input_cal.min[current_input];
                                min = input_cal.center[current_input];
                                fact = -100;
                } 
                else 
                {
                                // The stick is at center, or on the positive side.
                                // Thus, the range is from center to max, and
                                // we need positive percentages.
                                min = input_cal.center[current_input];
                                max = input_cal.max[current_input];
                                fact = 100;
                }
                // Calculate the percentage that the current stick position is at
                // in the given range, referenced to or from center, depending :P
                model.stick[current_input] =  fact * ((float)adc_in - min ) / (max - min);
                
                // If this input is configured to be reversed, simply do a sign-flip :D
                if ( model.rev[current_input] ) model.stick[current_input] *= -1;

                // Dual-rate calculation :D
                // This is very repetitive code. It should be fast, but it may waste code-space.
                float dr_val;
                // Test to see if dualrate-switch #1 applies to channel...
                if ( ( current_input == ( model.dr[0]-1) ) || ( current_input == ( model.dr[1]-1) ) )
                {
                                if ( !keys[KEY_DR1] )
                                                dr_val = ((float)model.dr[4])/100.0; 
                                else
                                                dr_val = ((float)model.dr[5])/100.0;

                                model.stick[current_input] *= dr_val; 
                }
                else
                // Test to see if dualrate-switch #1 applies to channel...
                if ( ( current_input == ( model.dr[2]-1) ) || ( current_input == ( model.dr[3]-1) ) )
                {
                                if ( !keys[KEY_DR2] )
                                                dr_val = ((float)model.dr[6])/100.0; 
                                else
                                                dr_val = ((float)model.dr[7])/100.0;

                                model.stick[current_input] *= dr_val; 
                }
        }
}


void ISR_timer(void)
{
        Timer1.stop(); // Make sure we do not run twice while working :P

        if ( !do_channel )
        {
                set_ppm_output( LOW );
                sum += seplength;
                do_channel = true;
                set_timer(seplength);
                return;
        }

        if ( cchannel >= model.channels )
        {
                set_ppm_output( HIGH );
                long framesep = framelength - sum;

                sum = 0;
                do_channel = false;
                cchannel = 0;
                set_timer ( framesep );
                return;
        }  

        if ( do_channel )
        {
                set_ppm_output( HIGH );

                // New format on stick values
                // model.stick contains percentages, -100% to 100% in float. To make the timer-handling
                // here as simple as possible. We want to calc the channel value as a  "ratio-value",
                // a float in the range 0..1.0. So, by moving the lower bound to 0, then cutting the
                // range in half, and finally dividing by 100, we should get the ratio value.
                // Some loss of presicion occurs, perhaps the algo' should be reconsidered :P
                long next_timer = (( chwidht * ((model.stick[cchannel]+100)/200) ) + chmin);
                
                // Do sanity-check of next_timer compared to chmax and chmin...
                while ( chmax < next_timer ) next_timer--;
                while ( next_timer < chmin ) next_timer++;

                // Update the sum of elapsed time
                sum += next_timer;

                // Done with channel separator and value,
                // prepare for next channel...
                cchannel++;
                do_channel = false;
                set_timer ( next_timer );
                return;
        }
}


#ifdef DEBUG
void serial_debug()
{
        int current_input;
        for (current_input=0; current_input<MAX_INPUTS; current_input++) 
        {
                Serial.print("Input #");
                Serial.print(current_input);
                Serial.print(" pct: ");
                Serial.print(model.stick[current_input]);
                Serial.print(" raw value: ");
                Serial.print(model.raw[current_input]);
                Serial.print(" min: ");
                Serial.print(input_cal.min[current_input]);
                Serial.print(" max: ");
                Serial.print(input_cal.max[current_input]);
                Serial.println();
        }
        Serial.print("Battery level is: ");
        Serial.println(battery_val);

        Serial.print("Average loop time:");
        Serial.println(avg_loop_time);

        Serial.print("Free RAM:");
        Serial.print( FreeRam() );
        Serial.println();
}
#endif

void dr_inputselect( int no, int in )
{
        if ( model.dr[menu_substate] < 0 ) model.dr[menu_substate] = 4;
        if ( model.dr[menu_substate] > 4 ) model.dr[menu_substate] = 0;

        lcd.setCursor(0 , 0);
        lcd.print("D/R switch ");
        lcd.print( no + 1 );
        //lcd.print("    ");
        
        lcd.setCursor(0 , 1);
        lcd.print("              ");
        lcd.setCursor(0 , 1);
        lcd.print("Input ");
        lcd.print(in+1);
        
        lcd.print(":  ");
        if ( ! model.dr[menu_substate] ) lcd.print("Off");
        else lcd.print(model.dr[menu_substate]);
        
        if ( check_key(KEY_INC) ) {
                model.dr[menu_substate]++;
                return;
        }
        else if ( check_key(KEY_DEC) ) {
                model.dr[menu_substate]--;
                return;
        }
        // Wrap around.
        return; 

}

void dr_value()
{
        int pos;
        int state;

        if ( menu_substate == 4) state = keys[KEY_DR1];
        else state = keys[KEY_DR2];
        
        pos = 4 + (menu_substate - 4) * 2;
        if (state) pos++;
        
        lcd.setCursor(0 , 0);
        lcd.print("D/R switch ");
        lcd.print( menu_substate - 3 );


        lcd.setCursor(0 , 1);
        lcd.print("              ");
        lcd.setCursor(0 , 1);
        lcd.print( state ? "HI" : "LO" );
        lcd.print(" Value :");
        
        lcd.print( model.dr[pos] );
        
        if ( !keys[KEY_INC] ) {
                if ( model.dr[pos] < 100) model.dr[pos] += 5;
                return;
        }
        else if ( !keys[KEY_DEC] ) {
                if ( model.dr[pos] > -100) model.dr[pos] -= 5;
                return;
        }
        
        return;
}
void ui_handler()
{
        int row; 
        int col;
        scan_keys();

        if ( check_key( KEY_UP) || check_key(KEY_DOWN))
                lcd.clear();

        if ( displaystate != MENU )
        {
                menu_substate = 0;
                if ( check_key(KEY_UP) && displaystate == VALUES  ) { 
                        displaystate = BATTERY; 
                        return; 
                }
                else if ( check_key(KEY_UP) && displaystate == BATTERY ) { 
                        displaystate = TIMER; 
                        return; 
                }
                else if ( check_key(KEY_UP) && displaystate == TIMER ) { 
                        displaystate = CURMODEL; 
                        return; 
                }
                else if ( check_key(KEY_UP) && displaystate == CURMODEL ) { 
                        displaystate = VALUES; 
                        return; 
                }

                else if ( check_key(KEY_DOWN) ) { 
                        displaystate = MENU; 
                        return; 
                }
        }
                
        digitalWrite(13, digitalRead(13) ^ 1 );

        switch ( displaystate )
        {
        case VALUES:
                int current_input;

                row = 0; col = 0;
                lcd.setCursor(col, row);
                lcd.print("            ");
                lcd.setCursor(col, row);

                lcd.print("S1:");
                lcd.print( keys[KEY_DR1] ? "On " : "Off" );
                lcd.print(" S2:");
                lcd.print( keys[KEY_DR2] ? "On " : "Off" );

                row = 2; col = 0;
                for (current_input=0; current_input<MAX_INPUTS; current_input++) {
                        if (row == 6)
                        {
                                row = 2;
                                col = 40;
                        }

                        // Overwriting the needed positions with
                        // blanks cause less display-flicker than
                        // actually clearing the display...
                        lcd.setCursor(col, row);
                        lcd.print("      ");
                        lcd.setCursor(col, row);
                        
                        char mod_indicator = NULL;
                        if (( keys[KEY_DR1] ) && (( model.dr[0] == current_input+1) || ( model.dr[1] == current_input+1)))
                                mod_indicator = '/';
                        if (( keys[KEY_DR2] ) && (( model.dr[2] == current_input+1) || ( model.dr[3] == current_input+1)))
                                if (mod_indicator) mod_indicator = '|';
                                else mod_indicator = '\\';
                        
                        if ( mod_indicator) lcd.print(mod_indicator);
                        else lcd.print(" ");
                        
                        lcd.print( current_input+1);
                        lcd.print(":");
                        // Display uses percents, while PPM uses ratio....
                        // New format on stick values
                        lcd.print( (int)model.stick[current_input] );

                        row++;
                }
      break;

    case BATTERY:    
                lcd.setCursor(0 , 0);
                lcd.print("Battery level: ");
                lcd.setCursor(0 , 1);
                lcd.print( "            ");
                lcd.setCursor(0 , 1);
                lcd.print( (float)battery_val/10);
                lcd.print("V");
                if ( battery_val < BATTERY_LOW ) lcd.print(" - WARNING");
                else lcd.print(" - OK");
                break;
      
    

        case TIMER:
                unsigned long delta;
                int hours;
                int minutes;
                int seconds;
                
        lcd.setCursor(0 , 0);
                lcd.print("Timer: ");
                lcd.print( clock_timer.running ? "Running" : "Stopped" );
                lcd.setCursor(5 , 1);
                lcd.print("         ");
                lcd.setCursor(5 , 1);
                if ( clock_timer.running )
                {
                        clock_timer.value = millis() - (clock_timer.start + clock_timer.init);
                }
                hours = ( clock_timer.value / 1000 ) / 3600;
                clock_timer.value = clock_timer.value % 3600000;
                minutes = ( clock_timer.value / 1000 ) / 60;
                seconds = ( clock_timer.value / 1000 ) % 60;
                if ( hours ) 
                {
                        lcd.print(hours);
                        lcd.print(":");
                }
                if ( minutes < 10 ) lcd.print("0");
                lcd.print( minutes );
                lcd.print(":");
                if ( seconds < 10 ) lcd.print("0");
                lcd.print( seconds );
                
        if ( check_key(KEY_INC) )
                {
                        if ( !clock_timer.running && !clock_timer.start )
                        {
                                clock_timer.start = millis();
                                clock_timer.value = 0;
                                clock_timer.running = true;
                        } 
                        else if ( !clock_timer.running && clock_timer.start ) 
                        {
                                clock_timer.start = millis() - clock_timer.value;
                                clock_timer.running = true;
                        } 
                        else if ( clock_timer.running ) 
                                clock_timer.running = false;
                        
                        return; 
                        
        }
                else if ( check_key(KEY_DEC) ) 
                {
                        if ( !clock_timer.running && clock_timer.start )
                        {
                                clock_timer.value = 0;
                                clock_timer.start = 0;
                                clock_timer.init = 0;
                        }
                        return; 
        }
                break;

                
        case CURMODEL:    
                lcd.setCursor(0 , 0);
                lcd.print("Model #: ");
                lcd.print( (int)current_model );
                lcd.setCursor(0 , 1);
                lcd.print("NAME (not impl)");
                break;


          
    case MENU:
                lcd.setCursor(0 , 0);
                switch ( menu_mainstate )
                {
                case TOP:
                        lcd.setCursor(0 , 0);
                        lcd.print("In MENU mode!");
                        lcd.setCursor(0 , 1);
                        lcd.print("UP to quit.");
                        lcd.setCursor(0 , 2);
                        lcd.print("DOWN to scroll");

                        menu_substate = 0;
                        if ( check_key(KEY_UP) )
                        {
                                displaystate = VALUES; 
                                lcd.clear();
                                return; 
                        }
                        else if ( check_key(KEY_DOWN) ) 
                        {
                                lcd.clear();
                                menu_mainstate = INVERTS; 
                                return; 
                        }
                        break;
    
    
                case INVERTS:
                        if ( menu_substate >= model.channels ) menu_substate = 0;
                        if ( menu_substate < 0) menu_substate = (model.channels - 1);
                        lcd.print("Channel invert");
                        lcd.setCursor(0 , 1);
                        lcd.print("Ch ");
                        lcd.print(menu_substate+1);
                        lcd.print( (model.rev[menu_substate] ?  ": Invert" : ": Normal"));

                        if ( check_key(KEY_UP) )
                        {
                                menu_mainstate = TOP; 
                                lcd.clear();
                                return; 
                        }
                        else if ( check_key(KEY_DOWN) )
                        {
                                menu_mainstate = DUALRATES; 
                                lcd.clear();
                                return; 
                        }

                        if ( check_key(KEY_RIGHT) )
                        {
                                menu_substate++; 
                                return; 
                        }
                        else if ( check_key(KEY_LEFT) )
                        {
                                menu_substate--; 
                                return; 
                        }
                        else if ( check_key(KEY_INC) || check_key(KEY_DEC) )
                        {
                                model.rev[menu_substate] ^= 1; 
                                return; 
                        }
                        break;
          
        case DUALRATES:
                        if ( menu_substate > 5 ) menu_substate = 0;
                        if ( menu_substate < 0) menu_substate = 5;
                
                        if ( check_key(KEY_UP) )
                        {
                                menu_mainstate = INVERTS; 
                                lcd.clear();
                                return; 
                        }          
                        if ( check_key(KEY_DOWN) )
                        {
                                menu_mainstate = EXPOS;
                                lcd.clear();
                                return;
                        }
                        if ( check_key(KEY_RIGHT) )
                        {
                                menu_substate++; 
                                return; 
                        }
                        else if ( check_key(KEY_LEFT) )
                        {
                                menu_substate--; 
                                return; 
                        }
                        
                        switch (menu_substate)
                        {
                        case 0:
                                dr_inputselect(0, 0);
                                return;
                        case 1:
                                dr_inputselect(0, 1);
                                return;
                        case 2:
                                dr_inputselect(1, 0);
                                return;
                        case 3:
                                dr_inputselect(1, 1);
                                return;
                        case 4:
                        case 5:
                                dr_value();
                                return;
                        default:
                                menu_substate = 0;
                                break;
                        }                 
                        break;
        
        case EXPOS:
                                      //________________
                        lcd.print("Input expo curve");
                        lcd.setCursor(0 , 1);
                        lcd.print("Not implemented");
                        // Possible, if input values are mapped to +/- 100 rather than 0..1 ..
                        // plot ( x*(1 - 1.0*cos (x/(20*PI)) )) 0 to 100
                        // Run in wolfram to see result, adjust the 1.0 factor to inc/red effect.
                        // Problem: -100 to 100 is terribly bad presicion, esp. considering that
                        // the values started as 0...1024, and we have 1000usec to "spend" on channels.

                        // NEW IDEA provided my ivarf @ hig: use bezier curves og hermite curves!
                        // Looks like a promising idea, but the implementation is still a bitt off
                        // on the time-horizon :P
                        if ( check_key(KEY_UP ) )
                        {
                                menu_mainstate = DUALRATES; 
                                lcd.clear();
                                return; 
                        }          
#ifdef DEBUG          
                        if ( check_key(KEY_DOWN ) )
                        {
                                menu_mainstate = DEBUG_DUMP;
                                lcd.clear();
                                return;
                        }
#else
                        if ( check_key(KEY_DOWN ) )
                        {
                                menu_mainstate = TOP;
                                lcd.clear();
                                return;
                        }

#endif
                        break;

#ifdef DEBUG          
                case DEBUG_DUMP:
                        lcd.setCursor(0 , 0);
                        lcd.print("Dumping debug to");
                        lcd.setCursor(0 , 1);
                        lcd.print("serial port 0");
                        serial_debug();          
                        if ( check_key(KEY_UP ) ) 
                        {
                                // FIXME: Remember to update the "Scroll up" state!
                                menu_mainstate = EXPOS; 
                                lcd.clear();
                                return; 
                        } else if ( check_key(KEY_DOWN ) )
                        {
                                menu_mainstate = SAVE;
                                lcd.clear();
                                return;
                        }
                        break;
#endif    
                default:
                        lcd.print("Not implemented");
                        lcd.setCursor(0 , 1);
                        lcd.print("Press DOWN...");
                        if ( check_key(KEY_DOWN ) ) menu_mainstate = TOP;
                        
                } // End of settings menu / MENU
                break;


        default:
                  // Invalid
                  return;
        } // End of main UI switch
        return;
}

#ifdef DEBUG
/* The following code is taken from the 
   Arduino FAT16 Library by William Greiman 
   The code may or may-not survive in the long run,
   depending on what licensing-terms we decide on.
   The license will be open source, but the FAT16lib
   is GPL v3, and I (fishy) am personally not so sure about that... 
   
   On the other hand... This code is a very "intuitive approach",
   so contacting the author may give us the option of relicencing just this bit...
*/
static int FreeRam(void) {
        extern int  __bss_end;
        extern int* __brkval;
        int free_memory;
        if (reinterpret_cast<int>(__brkval) == 0) 
        {
                // if no heap use from end of bss section
                free_memory = reinterpret_cast<int>(&free_memory)
                                                - reinterpret_cast<int>(&__bss_end);
        }
        else 
        {
                // use from top of stack to heap
                free_memory = reinterpret_cast<int>(&free_memory)
                                                - reinterpret_cast<int>(__brkval);
        }
        return free_memory;
}
#endif