A Turnkeyed C Application Program

// Turnkeyed Application Code Listing, C Language version.
// This is a complete real-time application program, with instructions on
// how to set up the program to AUTOSTART each time the processor starts up.
 
// Copyright 2009 Mosaic Industries, Inc.  All Rights Reserved.
//  Disclaimer: THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, WITHOUT ANY
//  WARRANTIES OR REPRESENTATIONS EXPRESS OR IMPLIED, INCLUDING, BUT NOT
//  LIMITED TO, ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS
//  FOR A PARTICULAR PURPOSE.
 
// ************************ Turnkeying an Application ********************
//
// This is the code for an example application.  The accompanying chapter
// presents a detailed explanation of this code.
// The code can run on a PDQ Board or PDQScreen.
 
// Description of the application:
// This program reads an input voltage, creates two pulse width modulated (PWM)
// signals whose average values track the input voltage, and reports the
// mean and standard deviation of the input voltage.
// One of the PWM signals is created using the HCS12 PWM subsystem on PORTP,
// and the other PWM output is created using the HCS12 ECT (Enhanced Capture/Timer)
// subsystem on PORTT.
// The following 3 tasks do the work:
 
// Task 1: Reads 10-bit Analog To Digital (ATD) input AN0,
//         measuring the voltage on a potentiometer
//         connected to AN0 (pin 24 of the Analog Field Header).
 
// Task 2:
//         1. This task outputs on PORTP bit 1 (PP1 is pin 15 of the
//         Digital Field Header) a PWM created without interrupts by the
//         16-bit concatenated PWM01 output operated by the
//         PWM subsystem of the HCS12 processor on PORTP.
//         2. This task outputs on PORTT bit 0 (PT0 is pin 24 of the Digital Field
//         Header) a PWM signal whose average equals the ATD input.  This PWM is
//         generated using an Output Compare associated with the ECT0_ID interrupt.
 
// Task 3: Every 1 second puts ATD voltage into a matrix, and every 10 seconds
//         displays the mean and standard deviation of the last 10 seconds
//         worth of data.
//
// The following issues are addressed:
//
//      Using the default C memory map as set up by the Mosaic IDE Plus
//      Proper initialization of tasks at startup
//      Autostarting
//      Interrupt service routines and interrupt attaching
//      Initialization of the heap memory manager
//      Timesliced multitasking
//      ColdOnReset() for secure restart
//      Floating point calculations
//      Going into production
 
 
 
// ************************ Default Memory Map ************************
 
// The "Making Effective Use of Memory" chapter in the C User Guide
// provides a complete description of the PDQ memory map.  This is a brief summary:
 
// 0x8000-BFFF (16K per page) in pages 0x00-0x13 holds up to 320Kbytes of
// compiled application code.  Pages 0x00-0x17 can be backed up to shadow flash
// and restored at each COLD restart using the SAVE.ALL interactive command.
// Pages 00-0x13 can also be write protected using WP.ALL.
 
// 0x8000-BFFF (16K per page) in pages 0x14-0x1C is paged RAM.
// Pages 0x14-1C are allocated as a heap area that holds FORTH_ARRAY data.
// The DEFAULT_HEAPSTART constant equals the heap start xaddress (0x188000), and
// the DEFAULT_HEAPEND constant equals the end xaddress of this region (0x1CBFFF),
// as declared in the C:\MosaicPlus\c\libraries\include\mosaic\heap.h file.
 
// 0x0800-0FFF and 0x2000-7FFF is 26K available common RAM
//      which hold C variables, C arrays,
//      as well as the pfa’s (parameter field areas) of FORTH_ARRAYs.
 
// 0x0680-07FF is available EEPROM referenced by the eeprom section
//      {EEPROM at 0x0400-067F is reserved for startup utilities
//       and interrupt revectoring}.
//       To locate a variable in eeprom, append the _eeprom tag, as in:
//          int testEEVar  _eeprom ;
 
// The operating system occupies onchip flash at 0x8000-BFFF on pages 0x38-3F,
//      common flash at 0xC000-FFFF, and reserves 0x8000-BFFF
//      on pages 0x1D-1F for system RAM and memory-mapped device addressing.
 
#include <mosaic\allqed.h>     // include all of the ansi C and mosaic functions
 
 
// *********************** ATD Data Gathering Task *********************
 
// This task gathers data from the Analog To Digital (ATD) converter
// and places it in a variable that is easily accessed by other tasks.
 
// Define the control registers and some useful constants:
 
#define ATD_INPUT_CHANNEL       0
// You can use any channel you want and place the input potentiometer on
// the corresponding ATD input pin.  For example, if 0 is your input
// channel, place the input signal on the pin labeled AN0 (pin24 of
// the Analog Field Header).
 
 
static float input_voltage;
// Holds voltage corresponding to latest result of ATD input. Because the
// contents of this variable are shared among several tasks, we use
// uninterruptable PokeFloatUninterrupted and PeekFloatUninterrupted to access it.
 
// The ATD reading is a 10-bit field left-justified in a 16-bit number.
// As explained in detail in the "Data Acquisition" chapter of the C User Guide,
// this ATD value can be treated as a 16-bit value that ranges from 0 to 65535.
// We want to convert this into a voltage that ranges from 0.0 Volts
// (the low reference voltage) to nearly 5.0 Volts (the high reference voltage).
// This involves solving the equation:
// Voltage=[(high.ref.voltage - low.ref.voltage)*measured.count/65536]+low.ref.voltage
// See the "Data Acquisition" chapter in the C User Manual for a
// discussion of this equation.
 
 
// First let’s define some constants:
#define FULL_SCALE_COUNTS       65536  // left-justified value is treated as 16 bits
#define LOW_VREF                0.0
#define HIGH_VREF               5.0
// NOTE: For maximum accuracy, place a voltmeter between AGND and +5VAN
//       (pins 1 and 2, respectively, on the PDQ Analog Field Header)
//       to measure +5VAN, and set HIGH_VREF equal to the result.
//       Or, if you want to use a signal other than the AGND analog ground
//       as your voltage ground, measure both signals with respect to your
//       chosen ground, and set the LOW_REF and HIGH_REF constants accordingly.
 
 
float _Q CountToVolts(uint count)
// This routine converts a 16-bit ATD measured count n { 0 <= n <= 65535 }
// to the corresponding floating point voltage r
// {typically, 0.0 <= r <= 5.0 }  by solving the equation:
// r = [ (high.ref - low.ref) * count / 65536 ]  + low.ref
{  return( ((HIGH_VREF - LOW_VREF) * count / FULL_SCALE_COUNTS) + LOW_VREF );
}
 
 
void _Q PokeFloatUninterrupted(float value, float* destination )
// stores value into the address specified by destination;
// the lock() and unlock() keywords guarantee that
// interrupts are disabled while the store operation occurs;
// this prevents corruption of data when two tasks are accessing the same
// 4-byte variables
{  uint prior_ccr_state = lock();  // save prior I-bit, disable irqs
   *destination = value;           // store the value while irqs are disabled
   unlock(prior_ccr_state);       // restore prior I-bit state
}
 
float  _Q PeekFloatUninterrupted(float *  source )
// fetches and returns the contents from the address specified by source;
// the lock() and unlock() keywords guarantee that
// interrupts are disabled while the fetch operation occurs;
// this prevents corruption of data when two tasks are accessing the same
// 4-byte variables
{  float source_contents;          // declare local variables
   uint prior_ccr_state;
   prior_ccr_state = lock();       // save prior I-bit, disable irqs
   source_contents =  *source;     // fetch the value while irqs are disabled
   unlock(prior_ccr_state);       // restore prior I-bit state
   return source_contents;
}
 
 
void _Q GatherData(void)
// This is the activation routine for the data gathering task.
// It continually acquires readings from the ATD, converts the readings
// to voltages, and updates the input_voltage variable that is accessed
// by other tasks.
{       uint sample;
        float sample_voltage;
        ATDOn(ATD_INPUT_CHANNEL);       // turn on ATD containing the input channel
        while(1)                        // start infinite loop
        {       sample = ATDSingle(ATD_INPUT_CHANNEL);  // get 1 sample
                sample_voltage = CountToVolts(sample);  // convert to volts
                PokeFloatUninterrupted(sample_voltage, &input_voltage); // store it
                Pause();                // let other tasks run
        }
}
 
 
// ********************* Pulse Width Modulation (PWM) Task ********************
 
// This task oversees the generation of two pulse-width modulated (PWM) outputs:
// 1. One of the outputs is generated by the hardware PWM subsystem on the HCS12
// processor which drives the PORTP pins.  This concatenated 16-bit-resolution
// PWM01 output appears at PORTP pin PP1 (pin 15 of the PDQ Digital Field Header).
// See the "PWM" chapter in the C User Manual.
// 2. The other pulse output is generated by the Enhanced Capture/Timer (ECT)
// subsystem on the HCS12 processor.  An Output Compare channel on ECT0 generates
// the pulse train on PORTT pin PT0 (pin 24 of the PDQ Digital Field Header).
// An interrupt service routine responds to the ECT0_ID interrupt to form
// each edge of this signal.
// See the "Timer Controlled I/O" chapter in the C User Manual.
 
// This PWM task's activation routine calculates the high time and low time
// of the PWM outputs based on the value of the input_voltage which is updated
// by the data gathering task.  A 100 millisecond (ms) period is used
// for both of the PWM outputs; consequently, we want their duty cycles to be equal.
// The goal is to set the duty cycle of each PWM output so that the time-average of
// the PWM signal equals the input_voltage (the analog voltage at the ATD input pin).
// This is achieved by solving the equation:
//      DutyCycle = (input_voltage - low_output) / (high_output - low_output)
//      in which low_output and high_output are the logic-low and logic-high
//      voltage levels that appear on the digital PWM output pins (PP1 and PT0)
//      in the low and high states, respectively.
 
 
// Given the duty cycle, and given our choice of a PWM period of 100 msec, we
// calculate the high_time and low_time of the PWM signal in terms of the timer
// counts; each timer count equals 1.6 microseconds, which is the default
// ECT timebase set by the operating system.  We assume here that the programmer
// has not installed a different value using ECTPrescaler().
// high_time is the number of timer counts that the signal is in the high state
// and low_time is the number of timer counts that the signal is in the low state
// during each 100 msec period.  high_time and low_time are calculated as:
//      high_time = duty_cycle * TIMER_COUNTS_PER_PERIOD
//      low_time = TIMER_COUNTS_PER_PERIOD - high_time
//              where TIMER_COUNTS_PER_PERIOD = 100 msec/1.6 microsec = 62,500.
 
// We also "clamp" high_time and low_time to a minimum value to match the
// PWM resolution to that of the incoming ATD signal (which has 10 bit resolution)
// and to prevent a situation where ECT interrupts are requested so rapidly
// that the processor can’t service one before the next interrupt request occurs.
 
// The ECT0 (output compare channel 0 of the ECT Enhanced Capture/Timer system)
// interrupt code in the subsequent section uses these calculated values
// to pulse width modulate the PORTT output port pin PT0.
 
// We define some variables and constants:
static uint high_time;   // the number of timer counts that PWM output is high
static uint low_time;    // the number of timer counts that PWM output is low
static float duty_cycle;
// the fractional portion of the full scale voltage represented by the analog input
 
#define LOW_OUTPUT_VOLTAGE      0.0    // = voltage on the PT output when it is low
#define HIGH_OUTPUT_VOLTAGE     5.0    // = voltage on the PT output when it is high
// NOTE: for maximum accuracy, the voltage outputs of pins PT0 and PP1 could be
//   measured in the low and high states and LOW_OUTPUT_VOLTAGE and
//   HIGH_OUTPUT_VOLTAGE could be set accordingly.
 
#define MS_PER_PERIOD   100    // use a 100 msec period for PWM output
                               // NOTE: the timer "rolls over" every 104.86 msec
 
#define TIMER_COUNTS_PER_PERIOD         62500
//   100 milliseconds corresponds to 62500 counts of 1.6 microseconds (usec)
//   each on the free-running timer.  The operating system sets the default
//   TCNT period to 1.6 usec.  We assume here that the programmer has not
//   installed a different value using ECTPrescaler().
//   For symmetry and simplicity, we also set the clock source period of the
//   PWM01 channel to equal 1.6us.
 
 
#define MINIMUM_HIGH_OR_LOW_TIME  ((int) 60)    // under 100usec
// we choose a minimum high or low time approximately equal to the maximum
// number of timer counts divided by 1000.  That is, we only require 10 bits of
// resolution from our PWM; after all, this is the resolution of the ATD reading
// that we are attempting to mimic.
 
 
void _Q CalcDutyCycle(void)
// implements the equation:
//     duty_cycle = (input_voltage-low.output)/(high_output-low_output)
// duty_cycle is in the range 0.0 to 1.0
{ float latest_input = PeekFloatUninterrupted(&input_voltage);
  duty_cycle = (latest_input - LOW_OUTPUT_VOLTAGE)
                 / (HIGH_OUTPUT_VOLTAGE - LOW_OUTPUT_VOLTAGE);
  duty_cycle = MIN((float) 1.0, duty_cycle) ;
  duty_cycle = MAX((float) 0.0, duty_cycle) ; // clamp to 0<=duty_cycle<=1.0
}
 
 
void _Q CalcHighAndLowTimes(void)
// saves high and low times as 16bit integer counts in the variables
// high_time and low_time using the equations:
//     high_time = duty_cycle * TIMER_COUNTS_PER_PERIOD
//     low_time  = TIMER_COUNTS_PER_PERIOD - high_time
// both high_time and low_time are clamped to a minimum so that timer interrupts
// don’t occur more frequently than they can be reliably serviced.
{ high_time = MAX((TIMER_COUNTS_PER_PERIOD * duty_cycle),MINIMUM_HIGH_OR_LOW_TIME);
  low_time = MAX((TIMER_COUNTS_PER_PERIOD - high_time),MINIMUM_HIGH_OR_LOW_TIME);
  high_time = TIMER_COUNTS_PER_PERIOD - low_time;
  // make sure that high_time + low_time is exactly one period despite clamping
}
 
 
// ************* PWM Output Using HCS12's PWM Subsystem *********
 
// PWM01    is a 16-bit concatenated PWM output comprising 8-bit channels 0&1.
// Its output appears on pwm1 pin = PP1 (pin 15 of the PDQ Digital Field Header).
// The driving clock period is chosen to be 1.6us to equal the ECT driving clock.
// PWM01 is declared as an active-high, non-center-aligned output.
// This means that the "duty" value written to the PWM01 channel
// should equal the high_time value calculated above.
// Reasoning: high_time is the 16-bit high time of a PWM signal with 100msec period
// and 1.6us driving clock.
// This is the definition of the "duty" value of an active-high 16-bit PWM signal.
// Thus, we can use the PWMDutyWrite() function to update the duty cycle
// as shown in the SetPulseParameters() function below.
 
#define CLOCKA_1_6USEC  32
// prescaler for clockA period = 32 * 0.05us Eclk.period = 1.6us
 
 
void _Q Setup16BitPWM(void)
// initialize PWM01 output on pin PP1 for 1.6us driving clock period,
// 16-bit concatenated channel, starting at 50% duty cycle.
{ PWMPrescaler(PWM_CLOCKA, CLOCKA_1_6USEC); // clockA period = 1.6us
  PWMUnscaledClock(PWM01);      // PWM01 uses unscaled clockA @ 1.6us
// now call PWMSetup() for PWM01, the next comment line recaps the prototype:
// PWMSetup( active_high, scaled_clock, centered, period, duty, channel_id )
  PWMSetup(TRUE, FALSE, FALSE, TIMER_COUNTS_PER_PERIOD, TIMER_COUNTS_PER_PERIOD/2, PWM01);
  PWMEnable(PWM01);         // enable PWM01, starts at 50% duty cycle
}
 
// ********************* ECT Output Compare Interrupt Code **********************
 
// This interrupt routine generates a pulse width modulated output on PortT
// pin PT0 based on the duty cycle calculated by the PWM task.
// We use C to define an interrupt handler.
//   Unless the "Fast Clear Mode" (available only for ATD and ECT systems),
//   the handler must clear the interrupt request flag by writing a 1 to it.
//   In this case, we use the fast clear mode.
// We install the interrupt handler using the Attach() function,
// and locally enable the interrupt.
 
#define PT0_ID 0         // name the channel_id that we're using
// don't confuse this with the kernel's ECT0_ID which is an argument for ATTACH
 
int  current_state = 0;  // used by ISR to track state
 
void _Q ECTPulseMaker( void )  // interrupt service routine for output compare 0
{    if( current_state == 0 )          // if output was low, and just toggled high...
   {    OCAction(OC_CLEAR_ACTION, PT0_ID);  // go low upon next successful compare
      TC0 += high_time;    // this access to TC0 auto-clears the flag bit
                           // if the output level just toggled high, the next output
   }                       // compare forces the pin low after the high_time
   else                            // else if the output level just toggled low...
   {    OCAction(OC_SET_ACTION, PT0_ID);  // set the mode/level bit so the next output
      TC0 += low_time;             // compare forces the pin high after low_time
   }                               // this access to TC0 auto-clears the flag bit
   current_state = !current_state; // toggle the state variable
}
 
MAKE_ISR(ECTPulseMaker); // needed for Attach() to work
 
void _Q InstallPulseMaker ( void )   // installs PWM output compare on PT0
{    uint current_tcnt_contents = TCNT;  // get current TCNT contents
     OutputCompare(PT0_ID);              // make ECT0/PT0 an output compare
   OCRegWrite((current_tcnt_contents - 1), PT0_ID); // start after 1 rollover period
   current_state = 0;                  // declare current state as low, and...
    OCAction(OC_SET_ACTION, PT0_ID);    // ...go active high upon successful compare
    ATTACH(ECTPulseMaker, ECT0_ID);     // post the interrupt handler
    ECTFastClear();                 // fast clear mode simplifies the ISR
    ECTInterruptEnable(PT0_ID);         // enable output compare 0 interrupt
}     // NOTE: the calling routine must ensure that interrupts are globally enabled!
 
 
 
// ************************* PWM Task Activation Routine ***********************
 
void  _Q SetPulseParameters( void )
// this is the activation roution for the pwm task.  It updates the
// values in high_time and low_time for use by the ECT0_ID output compare interrupt
// which generates the pwm output waveform on pin PT0.
// It also updates the PWM01 channel's duty parameter to control the
// output waveform on pin PP1.
// PWM01    is a 16-bit concatenated PWM output comprising 8-bit channels 0&1.
// Its driving clock period is chosen to be 1.6us to equal the ECT driving clock.
// PWM01 is declared as an active-high, non-center-aligned output by Setup16BitPWM().
// This means that the "duty" value written to the PWM01 channel
// should equal the high_time value calculated above.
// Reasoning: high_time is the 16-bit high time of a PWM signal with 100msec period
// and 1.6us driving clock.
// This is the definition of the "duty" value of an active-high 16-bit PWM signal.
// Thus, we use the PWMDutyWrite() function to update the duty cycle.
{  InstallPulseMaker();    // install ECT0 interrupt handler for pin PT0
   Setup16BitPWM();        // install PWM01 on pin PP1
    while(1)
   {  CalcDutyCycle();
      CalcHighAndLowTimes();
      PWMDutyWrite( high_time, PWM01 );  // write high_time to duty, explained above.
      Pause();              // let other tasks run
   }
}
 
// ************************** Statistics Task **************************
 
// This task samples the analog input voltage collected by the GatherData task
// once per second, stores it in a matrix, and calculates and prints to the terminal
// the mean and standard deviation of the data every 10 seconds.
// This task could easily use standard C arrays, but Forth arrays are
// used to show how paged RAM can be used to hold data structures.
// This use of paged RAM is especially useful when large amounts of data are involve.
 
 
FORTH_ARRAY Last10Voltages;
        // row matrix;  holds 1 voltage per second for past 10 seconds
 
// these index variables keep track of where data is placed in Last10Voltages:
static int matrix_index, last_index;
 
// these hold the derived statistics:
static float mean, standard_deviation;
 
float _Q RowMean(int rownum, FORTH_ARRAY * array_ptr)
// sums the elements in the specified row of the specified matrix and
// divides by the number of elements in the row to calculate the mean.
{   float accumulator = 0.0;
    int i, numcolumns = NUMCOLUMNS(array_ptr);  // see INCLUDE\MOSAIC\ARRAY.h file
    for(i=0; i < numcolumns; i++)
            accumulator += FARRAYFETCH(float, rownum, i, array_ptr);
    return (accumulator / numcolumns);
}
 
float _Q RowStandardDeviation(int rownum, FORTH_ARRAY* array_ptr, float row_mean)
// subtracts the row mean from each element and sums the squares of all
// resulting differences in the specified row of the specified matrix
// and takes the square root of the sum to calculate the standard deviation.
{   float accumulator = 0.0, temp;
    int i, numcolumns = NUMCOLUMNS(array_ptr);  // see \Mosaic\ARRAY.h file
    for(i=0; i < numcolumns; i++)
        {   temp = FARRAYFETCH(float, rownum, i, array_ptr) - row_mean;
            accumulator += (temp * temp);
        }
    return sqrt(accumulator);
}
 
void _Q InitFPArray(float value, FORTH_ARRAY * array_ptr)
// stores specified floating point value in each element of the array
// do not use this function to init arrays that hold char, int or long data
{   int r, c,
        numcolumns = NUMCOLUMNS(array_ptr),   // see \Mosaic\ARRAY.h file
        numrows = NUMROWS(array_ptr);
    for(c=0; c< numcolumns; c++)
            for(r=0; r < numrows; r++)
                    FARRAYSTORE(value, r, c, array_ptr);
}
 
void  _Q CalcStats( void )
// This routine calculates mean and standard deviation of the
// Last10Voltages matrix and stores them in variables.
{   mean = RowMean(0, &Last10Voltages);                     // row# = 0
    standard_deviation = RowStandardDeviation(0, &Last10Voltages, mean);
}
 
// The message on the terminal screen will look like this:
// Mean = x.xxx Volts  Standard Deviation = x.xxx Volts
 
void  _Q ShowStats( void )
        // writes a 1-line summary to terminal.
{ printf("\nMean = %5.4g Volts  Standard Deviation = %5.4g Volts",mean,standard_deviation);
  fflush(stdout);
}
 
void _Q LogDataAndShowStats( void )
// increments matrix_index every second,
// loads input_voltage data collected by task 1 into Last10Voltages array,
// and displays statistics to terminal every 10 seconds
{  float latest_input;
     // we need this temporary because we must do an uninterrupted fetch
     // from input_voltage, then pass the result to FARRAYSTORE
   matrix_index = (ReadElapsedSeconds()) % 10;  // 0<= matrix_index <= 9
   if(matrix_index != last_index)          // if a second has elapsed...
           {  latest_input = PeekFloatUninterrupted(&input_voltage);
              FARRAYSTORE(latest_input, 0, matrix_index, &Last10Voltages);
                                           // store reading in matrix
              last_index = matrix_index;   // update last_index
              if(matrix_index == 9)        // if 10 seconds have elapsed...
                      { CalcStats();       // calculate new statistics
                        ShowStats();       // write summary line
                      }
           }
}
 
void  _Q Statistics( void )
// this is the activation routine for the statistics task;
// it calculates and displays the mean and standard deviation of the data.
// NOTE: if you want to interactively debug on the serial1 port
//  while seeing the statistics printout on the serial2 port,
//  comment in the UseSerial2(); statement.  The default serial2 baudrate = 57600.
// This task calls PauseOnKey(). When you type a Carriage Return ("ENTER"),
// PauseOnKey() calls ABORT to end the program and enter the Forth monitor
// This lets you regain control of the processor.
{   DIM(float, 1, 10, &Last10Voltages);     // dimension as a 1-row array
    InitFPArray(0.0, &Last10Voltages);      // initialize array
    last_index = -1;                        // initialize last_index
//  UseSerial2();     // optional: this directs printout to serial2 port.
    printf("\nStarting Statistics task, will print once every 10 seconds...");
     printf("\nType a carriage return to abort the program\n");
    while(1)
       {  LogDataAndShowStats();         // calc and display statistics
          Pause();                       // let other tasks run
          PauseOnKey();  // pauses/resumes when key received; aborts when CR entered
       }
}
 
// ********************* BUILD TASKS  ****************************
 
// First declare the tasks and allocate their 1K task areas:
// FORTH_TASK (see USER.H) is the default task running QED-Forth;
// this task is automatically built and started upon each reset/restart;
// in the autostart routine FORTH_TASK puts itself ASLEEP so the end
// user can’t run Forth.
 
TASK ReadInputTask;        // data gathering task base xaddr
 
TASK ControlOutputTask;    // PWM task base xaddr
 
TASK StatisticsTask;       // statistics reporting task
 
// BUILD_C_TASK(HeapStart,HeapEnd,Base) and
// ACTIVATE(function_ptr, task_base_addr)
// macros are defined in INCLUDE\MOSAIC\MTASKER.h file.
 
void _Q BuildTasks( void )
// Empties the round robin task loop and then
// carefully builds the tasks every time we start up.
// Note that only the statistics task has access to the heap.
{  NEXT_TASK = TASKBASE;    // important! empties task loop before building
   SERIAL_ACCESS = RELEASE_ALWAYS; // allow sharing of serial ports
   BUILD_C_TASK(0,0,&ReadInputTask);
   BUILD_C_TASK(0,0,&ControlOutputTask);
   BUILD_C_TASK(DEFAULT_HEAPSTART,DEFAULT_HEAPEND,&StatisticsTask);
}  // default heap start and end are defined in C:\MosaicPlus\c\libraries\include\mosaic\HEAP.h
 
 
void _Q ActivateTasks( void )
// associate activation routines with each of the tasks.
// we pass a function pointer and task base address to the ACTIVATE routine.
{    ACTIVATE(GatherData, &ReadInputTask);
   ACTIVATE(SetPulseParameters, &ControlOutputTask);
   ACTIVATE(Statistics, &StatisticsTask);
}
 
 // ********************* SET UP AUTOSTART ROUTINE *********************
 
// We’ll designate the top level word main as the PRIORITY.AUTOSTART: routine.
// Every time the PDQ Board is powered up or reset, the main routine will
// automatically be executed.
// main() zeros the variable area and initializes the heap.
// During debugging, you can comment out the ASLEEP command in main and comment in
// the UseSerial2() command in Statistics to allow Serial1 to be used for
// debugging via the terminal.  The FORTH task which runs main() has access to
// all defined function names declared using the _Q keyword;
// the names are sent to the board via the .DLF download file.
// main() initializes the variables and elapsed time clock,
// and builds and activates the tasks.
// It releases control of the serial line, starts the timeslicer, and PAUSEs
// to begin execution of the application.
// After debugging is complete, the optional command which
// specifies a COLD restart can be inserted;
// this command is "commented out" in the code shown here.
 
 
void _Q InitVariables(void)
// init static variables  at runtime, and
// it's a good idea to erase the parameter field struct of a Forth array at startup.
{
    input_voltage = 0;
    current_state = 0;
    high_time = low_time = 0;
    // erase the parameter field struct of a Forth array:
    FillMany  ((xaddr) &Last10Voltages, (long) sizeof(FORTH_ARRAY), (char) 0);
    matrix_index = last_index = 0;
    mean = standard_deviation = duty_cycle = 0.0;
}
 
 
int main(void)
// this is the highest level routine in the turnkeyed application.
{   InitVariables();        // init variables, delete arrays
    INIT_DEFAULT_HEAP();    // it’s important to init heap at startup
    InitElapsedTime();      // initialize qed elapsed time clock
    BuildTasks();           // initialize user areas of the tasks
    ActivateTasks();        // associate action routine with each task
// the following command is removed during debugging;present in final version
    //  ColdOnReset();      // ensures full initialization upon each reset
// the following ASLEEP command can be removed during debugging
// if the UseSerial2() command is inserted in the Statistics() function:
    STATUS = ASLEEP;        // puts forth task asleep so statistics can print
    RELEASE(SERIAL);        // in case another tasks needs to use serial
    StartTimeslicer();      // starts elapsed time clock, enables interrupts
    Pause();                // start next task immediately
    return 0;
}
 
 
// To compile this file, click Build -> Build from the toolbar in the Mosaic IDE Plus.
// Then use the terminal to download the resulting turnkey.dlf file
// into the controller.
// Note that by default the download file will automatically back up the code
// image to shadowed flash.
// To make sure this option is enabled, go to
//    Project -> Project compiler options
// and check the checkbox next to:
//    "Include save-to-flash instructions in download file"
// This option causes the program to be automatically reloaded into memory
// upon each COLD restart.
 
// Be sure to select:
//    Set Autostart in download file
// this will install main() as the routine that is automatically executed
// each time the board is reset or powered on.
// This is done via the priority.autostart vector
// at the top of page 0x0F shadow flash AND page 0x0F SRAM.
 
// You can optionally select:
//    Enable Region 1 (Pages 0-F) Write Protect
//    Enable Region 2 (Pages 10-17) Write Protect
// to write protect all the protectable pages; The C User Guide
// document explains these options.
 
// With Autostart enabled, the next restart will automatically execute main().
// NOTE:   To erase the autostart vector and return to the QED-Forth prompt,
//         type a CR ("ENTER") to abort the program, then type at the terminal:
//                      NO.AUTOSTART
//         If you have put the FORTH_TASK asleep so that it does not
//         respond to the terminal,
//         activate the Special Cleanup Mode by installing the jumper
//         labeled "Clean" and pressing the reset button.
//         The Special Cleanup Mode erases the autostart vector and restores the
//         board to a "pristine" condition (it also sets the default
//         baud rate to 115200, default serial = serial1 port;
//         invoke BAUD and/or USE.SERIAL2 if you need to change the defaults).
//
 
 
// ************** GOING INTO PRODUCTION ***************
 
// To make sure your project is ready to load onto a pristine board,
// check that at minimum both of these options are enabled:
//    Set Autostart in download file
//    "Include save-to-flash instructions in download file"
// Remember, these options can be accessed via the toolbar of the Mosaic IDE Plus
// Click, Project -> Project compiler options
// Now, simply download the TURNKEY.DLF file, power cycle the Board
// and it will automatically run the application!